Citrus Nutrition and Quality - American Chemical Society

10 Fruit Handling and Decay Control Techniques Affecting Quality

Downloaded by UNIV OF CINCINNATI on May 31, 2016 | http://pubs.acs.org Publication Date: December 15, 1980 | doi: 10.1021/bk-1980-0143.ch010

G. ELDON BROWN Florida Department of Citrus, University of Florida, Institute of Food and Agricultural Sciences, Agricultural Research and Education Center, P.O. Box 1088, Lake Alfred, FL 33850

Information concerning various pre- and postharvest techniques used i n the handling and processing of citrus fruits which affect quality has been compiled and summarized within the scope of this chapter. Major cultural and genetic influences on quality are not considered. Quality i s influenced by physiological and pathological factors and is measured i n both specific and general terms. Quality parameters involved with internal composition are usually defined, but i n many instances causes related to off-flavors have not yet been i d e n t i f i e d . Factors which detract from the external appearance and affect the saleability of citrus f r u i t d e f i n i t e l y have to be considered when discussing quality. These factors associated with the rind include color, softness, and various forms of rind breakdown. Keeping quality i s another important aspect, and various handling and decay control techniques influence the occurrence of decay caused by several different fungal pathogens. Quality can be adversely affected by many of the techniques, but several specific methods have been developed to improve quality at harvest and/or maintain it during storage or t r a n s i t . Preharvest techniques which i n f l u e n c e q u a l i t y Lead arsenate s p r a y s . I n t e r n a l f r u i t q u a l i t y can be i n fluenced by spraying t r e e s w i t h lead arsenate a t post-bloom Oranges ( C i t r u s s i n e n s i s ( L . ) Osbeck) are more a f f e c t e d than g r a p e f r u i t ( C i t r u s p a r a d i s i M a c f . ) . The use o f lead arsenate to reduce t i t r a t a b l e a c i d i t y o f F l o r i d a g r a p e f r u i t has been a standard procedure f o r many y e a r s . Red g r a p e f r u i t sprayed w i t h lead arsenate contained s i g n i f i c a n t l y l e s s a c i d than d i d the unsprayed f r u i t ( 2 ) . A c i d i n f r u i t sprayed w i t h the highest r a t e (1.9 g/1) was only h a l f t h a t w i t h the lowest r a t e (O.5 g / 1 ) . In a d d i t i o n to a c i d i t y r e d u c t i o n , arsenated g r a p e f r u i t contained s l i g h t l y l e s s reducing sugar, s i g n i f i c a n t l y more non-reducing

0-8412-0595-7/80/47-143-193$08.00/0 © 1980 American Chemical Society

Nagy and Attaway; Citrus Nutrition and Quality ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

194

CITRUS NUTRITION AND QUALITY


sugar, and more t o t a l sugar than nonarsenated f r u i t . The b i o f l a v o n o i d content and pH were a l s o s i g n i f i c a n t l y higher i n the sprayed f r u i t (3J. A p p l i c a t i o n s of lead arsenate to Temple oranges lowered the t i t r a t a b l e a c i d content but not the s o l u b l e s o l i d s or percentage j u i c e ( 4 ) . Decay, peel i n j u r y , or c r e a s i n g (a r i n d malformation) were not i n f l u e n c e d but l e g a l m a t u r i t y was advanced by 15 to 20 days. F l o r i d a r e g u l a t i o n s (5) r e s t r i c t the use of lead arsenate to g r a p e f r u i t . C o l o r . Color of c i t r u s f r u i t at m a t u r i t y i s a major c r i t e r i o n of consumer appeal. In humid, s u b t r o p i c a l c l i m a t e s , c i t r u s f r u i t s w i l l reach m a t u r i t y w i t h a considerable amount of c h l o r o p h y l l s t i l l remaining i n the r i n d . T h e r e f o r e , c o n s i d e r a b l e i n t e r e s t has been shown i n the area of c o l o r enhancement through the use of m a t e r i a l s a p p l i e d to mature f r u i t before harvest. The f i n a l c o l o r of most orange c u l t i v a r s i s produced by a dec l i n e i n c h l o r o p h y l l pigments and an accumulation o f c a r o t enoids. The f i n a l c o l o r on most lemon ( C i t r u s limon L. Burm.), lime ( C i t r u s a u r a n t i f o l i a (Christm.) Swing) and g r a p e f r u i t c u l t i v a r s i s produced by a d e c l i n e i n c h l o r o p h y l l pigments and l i t t l e or no net increase i n carotenoids (6_). Removal of c h l o r o p h y l l from c i t r u s f r u i t s w i t h preharvest a p p l i c a t i o n s of ethephon (2-chloroethylphosphonic a c i d ) , which decomposes to produce ethylene ( 7 ) , has been s u c c e s s f u l l y achieved (8, 9, 10^, 11_, 12). Concentrations between 50 to 200 mg/1 as a preharvest spray 5 to 20 days before harvest to Robinson and Lee tangerines ( C i t r u s r e t i c u l a t a Blanco) r e s u l t e d i n p a r t i a l c h l o r o p h y l l l o s s (3egreening). Less postharvest degreening was r e q u i r e d to achieve acceptable c o l o r , and keeping q u a l i t y of the f r u i t during storage was improved (10^, 11). Concentrations of 200 to 500 mg/1 induced varying degrees of f r u i t loosening and, o f t e n , f r u i t drop of Robinson, Lee, Nova, and Dancy tangerines and Hamlin oranges (10). Leaf a b s c i s s i o n a l s o o c c u r r e d , p a r t i c u l a r l y a t the higher c o n c e n t r a t i o n . Damage to f r u i t by •'plugging", removal of a p o r t i o n of the peel at the stem-end at harvest, was reduced by the ethephon sprays. Preharvest a p p l i c a t i o n s of ethephon to Robinson tangerines s i g n i f i c a n t l y reduced the i n c i dence of anthracnose caused by C o l l e t o t r i c h u m g l o e o s p o r i o i d e s (Penz.) Sacc. during storage (13JT Control was a t t r i b u t e d to p h y s i o l o g i c a l changes w i t h i n the r i n d a s s o c i a t e d w i t h c a r t e n o i d accumulation which occurred due to the presence of low l e v e l s of e t h y l e n e . A l l c u l t i v a r s of c i t r u s , however, do not respond to ethephon treatment. Preharvest a p p l i c a t i o n s to Bearss lemons were r e l a t i v e l y i n e f f e c t i v e f o r inducing degreening even though the ethephon was absorbed and ethylene was produced (9). Simil a r r a t e s of a p p l i c a t i o n as a postharvest dip induced degreening, suggesting t h a t a f a c t o r such as a u x i n , g i b b e r e l l i n , or c y t o k i nin from the t r e e i n h i b i t e d the response to e t h y l e n e . E l Zeftawi and G a r r e t t (8) observed t h a t ethephon markedly reduced a c i d i t y of j u i c e from green-colored V a l e n c i a oranges. In f r u i t


10.

BROWN

Fruit

Handling

and

Decay

Control

195


excluded from l i g h t a f t e r ethephon a p p l i c a t i o n , f l a v o n o i d s and polyphenols were increased i n j u i c e from green-colored f r u i t or f r u i t undergoing regreening. Carotenoids were a l s o increased at the orange-colored and regreened ( a d d i t i o n a l s y n t h e s i s of c h l o r o p h y l l ) stages, but decreased at the green stage. Ethephon d i d not cause e a r l i e r maturation of Shamouti oranges (14). Growth r e g u l a t o r s . G i b b e r e l l i c a c i d (GA), 2 , 4 - d i c h l o r o phenoxyacetic a c i d (2,4-D), and 2 , 4 , 5 - t r i c h l o r o p h e n o x y a c e t i c a c i d (2,4,5-T) are growth r e g u l a t o r s evaluated on c i t r u s f r u i t s to improve q u a l i t y a t / o r a f t e r harvest. In g e n e r a l , s i g n i f i c a n t changes i n i n t e r n a l q u a l i t y have not been observed w i t h these growth r e g u l a t o r s {6, 15, 16, 17, 18, 19, 20), t h e i r e f f e c t s being r e s t r i c t e d p r i m a r i l y to the r i n d . The use of GA has been p a r t i c u l a r l y s u c c e s s f u l on Washington Navel oranges grown i n most c i t r u s r e g i o n s . A p p l i c a t i o n s of GA r e t a r d senescence of the r i n d due to high enzymatic and metabolic a c t i v i t i e s l a t e i n the season (21_, 22) which delay l o s s of c h l o r o p h y l l and accumu l a t i o n of c a r o t e n o i d pigments ((5, 1!5, 16_, 17, 23, 2£, 25, 26, 27_, 28). A p p l i c a t i o n s of 2,4-D or c l o s e l y r e l a t e d compounds" have been s u c c e s s f u l l y combined w i t h GA. The e f f e c t of 2,4-D has been p r i n c i p a l l y to reduce f r u i t drop or increase f r u i t s i z e due to a t h i n n i n g e f f e c t (6_, _15, Γ7, 28, 29, 30, 31, 32). A p p l i c a t i o n s of GA and 2,4-D have been shown to extend the harvesting season of g r a p e f r u i t (30, 31_, 33, 34), producing a f i r m e r f r u i t and, i n some i n s t a n c e s , i n c r e a s i n g f r u i t s i z e (33). F r u i t t r e a t e d w i t h these growth r e g u l a t o r s withstood deformity due to handling and packing s i g n i f i c a n t l y b e t t e r than untreated f r u i t (34). G i b b e r e l l i c a c i d and 2,4-D alone and i n combination reducicT germination of seed i n mature g r a p e f r u i t (30). Darkened blemishes, some d i s c o l o r a t i o n o f the r i n d and increased r i n d t h i c k n e s s were some of the u n d e s i r a b l e e f f e c t s of GA on g r a p e f r u i t (33). Regreening due to the a p p l i c a t i o n of GA can be a problem on V a l e n c i a oranges and g r a p e f r u i t (15_, 30, 35, 36, 3 7 ) , and f r u i t deformity has o c c a s i o n a l l y been observed w i t h V a l e n c i a oranges (35). Postharvest decay of f r u i t sprayed w i t h growth r e g u l a t o r s has been reported to be reduced (15, 16, Γ7, 23, 31). This has been a t t r i b u t e d to fewer i n j u r i e s being formed i n f i r m f r u i t r e c e i v i n g growth r e g u l a t o r s as w e l l as to growth of the decay organisms being decreased i n l e s s senescent peel (16). Anatomi cal changes a s s o c i a t e d w i t h r i n d senescence were retarded by GA sprays (_6, 16). G i b b e r e l l i c a c i d caused an i n c r e a s e i n v a l e n cene, an e s s e n t i a l o i l component (27). V a l e n c i a oranges sprayed with 2,4-D and GA were f i r m e r , evolved l e s s e t h y l e n e , and showed slower malonic a c i d accumulation i n the j u i c e (20). G i b b e r e l l i c a c i d reduced B r i x ( p r i m a r i l y sugars) and a c i d i t y i n green-colored V a l e n c i a oranges ( 8 ) . Chlorophenoxyacetic a c i d (CLPA) and 2,4,5-T a p p l i e d to mandarins increased j u i c e content and peel moisture. Treated f r u i t s u f f e r e d l e s s l o s s of weight, v i t a m i n C, and sugar during storage (38). G i b b e r e l l i c a c i d



196


a p p l i e d to lemon t r e e s caused the f r u i t to remain greener and to develop the y e l l o w lemon c o l o r l e s s r a p i d l y i n storage (39). The b e n e f i t s of GA a p p l i c a t i o n s to lemons are a more d e s i r a b l e seasonal harvest p a t t e r n i n r e l a t i o n to market demands, a l a r g e r percentage of f r u i t w i t h a long storage l i f e , and a decrease i n the number of small f r u i t ( 6 ) . A p p l i c a t i o n s of GA to Clementine mandarins s i g n i f i c a n t l y delayed f r u i t c o l o r i n g , l o s s of a c i d , and an i n c r e a s e i n s o l u b l e s o l i d s (40). Growth r e g u l a t o r s have been s u c c e s s f u l l y used to c o n t r o l p h y s i o l o g i c a l r i n d d i s o r d e r s . Rind s t a i n i n g of navel oranges was reduced w i t h GA a p p l i c a t i o n s (41, 42, 4 3 ) , as was the accumulation of r i n d exudate on mature f r u i t (44). Water spot of navel oranges, caused by surface deposits of water e n t e r i n g the r i n d , can be reduced by GA sprays (45, 46). Rough and t h i c k peel of l a r g e f r u i t s i z e s of Shamouti oranges was reduced s i g n i f i c a n t l y by applying 2 , 2 r d i m e t h y l h y d r a z i d e (SADH) and 2chloroethyltrimethylammonium c h l o r i d e (CCC) (47). GA a l s o r e duced p u f f i n g and c r e a s i n g of oranges (23, 3 Λ 48, 49). Gran u l a t i o n i n V a l e n c i a oranges was reduced w i t h 2,4-D sprays (29). Preharvest sprays of benzyl adenine, a c y t o k i n i n , and 2,4-D tended to decrease s u s c e p t i b i l i t y of g r a p e f r u i t to c h i l l i n g i n j u r y , a c o l d storage d i s o r d e r of the r i n d (50). Additional i n f o r m a t i o n on the e f f e c t of growth r e g u l a t o r s on c i t r u s has been compiled by Coggins and Hi e l d ( 6 ) . Aging, a w r i n k l i n g of the peel at the sten-end of V a l e n c i a oranges caused from l o s s of m o i s t u r e , was reduced by applying Pinolene ( p o l y - l - p - m e n t h e n - 8 , 9 - d i y l ) , an a n t i t r a n s p i r a n t p l a s t i c , 1-2 months before harvest. At both 1 and 3%, Pinolene reduced stem-end aging and moisture l o s s of V a l e n c i a oranges during storage (51). S o l u b l e s o l i d s and a c i d i t y were reduced, but i n t e r n a l q u a l i t y was s t i l l acceptable (52). Handling techniques at harvest which i n f l u e n c e q u a l i t y Harvest methods. C i t r u s f r u i t s are harvested almost e n t i r e l y by hand. I n i t i a l l y , c i t r u s f r u i t s were c l i p p e d when harvested because the stem does not separate e a s i l y from the f r u i t at p i c k i n g . However, as t h i s procedure was slow and a c e r t a i n amount of c l i p p e r i n j u r y o c c u r r e d , h a r v e s t i n g by p u l l i n g became the predominant method (53). P u l l i n g or snapping, a breaking-by-bending process, causes the stem to break c l o s e to the f r u i t . In many i n s t a n c e s , a l l or p o r t i o n s of the button ( c a l y x and d i s k ) may be removed from the f r u i t . The button harbors fungi which may l a t e r cause decay during storage and thus reduce keeping q u a l i t y . A comparison of decay i n p u l l e d versus c l i p p e d f r u i t showed t h a t stem-end r o t , caused by D i p l o d i a n a t a l e n s i s P. Evans and Phomopsis c i t r i F a w c , was reduced by p u l l i n g (53, 54, 55). Levels of decay caused by A l t e r n a r i a c i t r i E l l . and P i e r c e , however, were increased (55). Spot p i c k i n g , p r i n c i p a l l y on the b a s i s of c o l o r , can be used to



10.

BROWN

Fruit

Handling

and Decay

Control

197

aid i n the harvest of high q u a l i t y f r u i t . S i t e s and R e i t z (56, 57, 58) showed t h a t the best c o l o r e d f r u i t contained the highest s o l u b l e s o l i d s and v i t a m i n C c o n t e n t , and u s u a l l y had a higher s o l u b l e s o l i d s / t i t r a t a b l e a c i d r a t i o . Spot p i c k i n g f o r j u i c e content had no p r a c t i c a l a p p l i c a t i o n (58). Unnecessary rough h a n d l i n g , no matter whether f r u i t are harvested by c l i p p i n g or p u l l i n g , causes i n j u r i e s to the r i n d which are r e a d i l y i n f e c t e d by decay f u n g i . The simple p r a c t i c e of c a r e f u l handling during harvesting has an i n d u b i t a b l y s i g n i f i c a n t i n f l u e n c e upon q u a l i t y . I t has been shown i n numerous studies t h a t rough handling s i g n i f i c a n t l y reduces keeping q u a l i t y of c i t r u s f r u i t s (59^, 6Ό, 6^, 62) and q u a l i t y decreases with increased s e v e r i t y o f the i n j u r i e s (61). Gently handled g r a p e f r u i t held under humid, shaded c o n d i t i o n s u n t i l packing were more r e s i s t a n t to deformation than f r u i t roughly-handled and exposed to the sun. S u s c e p t i b i l i t y t o permanent deform a t i o n increased w i t h advancing m a t u r i t y (64). Physiological disorders. P h y s i o l o g i c a l d i s o r d e r s are a l s o i n f l u e n c e d by handling a t harvest. Blossom-end c l e a r i n g i s a symptom of b r u i s i n g which i s common on f u l l y mature t h i n skinned, seedless g r a p e f r u i t t h a t have been subjected to rough handling (63). This d i s o r d e r i s u s u a l l y v i s i b l e w i t h i n 24 hours a f t e r b r u i s i n g and i s manifested by water soaking of the blossom-end caused by exudation of j u i c e from broken v e s i c l e s w i t h i n the pulp. The d i s o r d e r i s more p r e v a l e n t i n rough handled mature f r u i t (62). O l e o c e l l o s i s or o i l s p o t t i n g occurs when f r u i t are i n j u r e d during handling causing a r e l e a s e of o i l from damaged glands. The o i l i s t o x i c to surrounding healthy c e l l s of the r i n d causing a c o l l a p s e and d i s c o l o r a t i o n o f the area (65). Turgid f r u i t are more s u b j e c t to the d i s o r d e r (42, 66, (D7, 68, 69, 70) and harvesting should p r e f e r a b l y be delayed u n t i l the r a t e o f water l o s s from the t r e e exceeds the r a t e o f water uptake. F r u i t harvested w h i l e wet or damp from r a i n , overhead i r r i g a t i o n , dew or fog are very s u s c e p t i b l e to o l e o c e l l o s i s . Damaged areas c o l l a p s e and darken, causing the o i l glands to remain prominent. Such areas w i l l not degreen with ethylene but w i l l darken unless f r u i t are held i n very high ( c a , 95% RH) humidity a f t e r harvest p r i o r to washing and waxing (68). Use o f ethephon to enhance r i n d c o l o r break caused an increase i n s u s c e p t i b i l i t y t o o l e o c e l l o s i s i n Washington Navel oranges (71). I t was suggested t h a t an increase i n f r u i t r i n d hydration brought about by stomatal c l o s u r e induced i n creased s u s c e p t i b i l i t y to o l e o c e l l o s i s . Z e b r a - s k i n , a p h y s i o l o g i c a l d i s o r d e r of t a n g e r i n e s , i s i n f l u e n c e d a l s o by water c o n d i t i o n s of the t r e e . Losses can be d i s a s t r o u s i f f r u i t are harvested from t r e e s subjected to heavy r a i n s or i r r i g a t i o n f o l l o w i n g a period of severe drought (72, 73). S u s c e p t i b l e f r u i t are so f r a g i l e t h a t the normal packing processes o f washing, d r y i n g , and waxing cause the peel to darken over the



198


segments, p a r t i c u l a r l y i n f r u i t p r e v i o u s l y degreened w i t h ethylene. Once f r u i t are separated from the t r e e , they are no longer provided w i t h a source of moisture. Loss of water from the f r u i t a f t e r harvest before waxing can occur during delays i n handling. This can o f t e n lead to a p h y s i o l o g i c a l d e t e r i o r a t i o n of the r i n d near the stem-end c a l l e d stem-end r i n d breakdown (68, 74, 75, 76). The d i s o r d e r i s p a r t i c u l a r l y troublesome i f f r u i t are helcFtwo or more days at low r e l a t i v e h u m i d i t i e s and high r a t e s of a i r f l o w between harvesting and waxing. R e l a t i v e h u m i d i t i e s l e s s than 85% during degreening aggravate t h i s d i s order (74). The c o n d i t i o n i s c h a r a c t e r i z e d by a c o l l a p s e of the r i n d t i s s u e around the button which may extend several c e n t i meters towards the f r u i t equator. A r i n g of t i s s u e of approximately 3 mm immediately surrounding the button which i s immune to breakdown was observed to l a c k stomata and to be covered w i t h a heavy d e p o s i t of e p i c u t i c u l a r wax (77). S t y l a r - e n d breakdown, a p h y s i o l o g i c a l d i s o r d e r of Persian l i m e , i s a l s o enhanced by rough handling a t harvest or during packing (78, 79, 80, 81). Rough h a n d l i n g , however, i s not the primary cause. Davenport and h i s co-workers (82, § 2 * 84, 85) found t h a t rupture of the v e s i c l e s i n the p u l p T i b e r a t i r l j u i c e which invaded the r i n d . The j u i c e passed more e a s i l y from the c e n t r a l a x i s to the r i n d at the s t y l a r - e n d than a t the stem-end. F r u i t turgor a s s o c i a t e d w i t h thermal expansion of f l u i d w i t h i n the j u i c e v e s i c l e s increased i n t e r n a l pressure to a magnitude s u f f i c i e n t to rupture some j u i c e v e s i c l e s , e s p e c i a l l y those i n l a r g e r s i z e d f r u i t . S t y l a r - e n d breakdown i n limes can be cont r o l l e d by m a i n t a i n i n g a s t r i c t p i c k i n g schedule so t h a t f r u i t i s harvested before i t becomes too l a r g e , by c o n t r o l l i n g p o s t harvest f r u i t temperature by hydrocooling i n the f i e l d and/or assuring t h a t harvested f r u i t i s kept shaded throughout the day, p i c k i n g f r u i t w i t h r i n d o i l r e l e a s e pressure of 4*55 kg and g r e a t e r , or reducing t u r g o r by f o r c e d evaporation (84, 85). Central C a l i f o r n i a Washington Navel oranges are s u s c e p t i b l e to a r i n d s t a i n i n g d i s o r d e r which i s a l s o p h y s i o l o g i c a l i n nature. The d i s o r d e r becomes apparent soon a f t e r processing and v a r i e s from brownish d i s c o l o r a t i o n s on the r i n d to severe cases of surface breakdown. E a r l y i n the season w e l l - c o l o r e d f r u i t showed more s t a i n i n g than f r u i t picked green and degreened with e t h y l e n e . F r u i t harvested l a t e i n the season s t a i n e d more than f r u i t harvested i n e a r l y or mid-season. Rough p i c k i n g p r a c t i c e s and prolonged brushing increased r i n d s t a i n i n g (42, 86). Mechanical h a r v e s t i n g . E f f o r t s to develop systems to mechanically harvest c i t r u s f r u i t s , p a r t i c u l a r l y oranges, have been i n progress f o r s e v e r a l y e a r s . U s u a l l y , these systems have been developed to handle f r u i t destined f o r processed as opposed to f r e s h u t i l i z a t i o n . Some e f f o r t s , however, have been made to



10.

BROWN

Fruit

Handling

and Decay

Control

199

u t i l i z e mechanically harvested f r u i t f o r f r e s h f r u i t marketing. Due to the rough handling procedures i n v o l v e d , f r u i t harvested mechanically are s u b j e c t t o more i n j u r i e s than are f r u i t harvested by hand. Increased i n j u r i e s lead t o higher l e v e l s o f decay (87, 88, 89) and increased moisture l o s s (90), In a d d i t i o n t o i n j u r i e s , mechanically harvested f r u i t often have a d hering long stems (89, 9 1 ) , which r e q u i r e removal before f r e s h u t i l i z a t i o n . Use o f e f f e c t i v e f u n g i c i d e s , a p p l i e d before or immediately a f t e r h a r v e s t , suppressed decay so t h a t l e v e l s were comparable to t h a t i n hand-harvested f r u i t (91, 9 2 ) . F r u i t harvested mechanically f o r processed purposes r e q u i r e the use o f c e r t a i n grading techniques a t the processing plants (93, 94, 95) t o remove c u l l s and t r a s h . Such techniques are g e n e r a l l y not needed to such an extent f o r hand-harvested f r u i t . A b s c i s s i o n chemicals, which reduce the attachment f o r c e of the f r u i t t o the stem, have been s t u d i e d as an a i d to mechani c a l h a r v e s t i n g (96). The more e f f e c t i v e a b s c i s s i o n chemicals act by damaging the r i n d , causing r e l e a s e o f ethylene which weakens c e l l s w i t h i n the a b s c i s s i o n l a y e r , r e s u l t i n g i n a b s c i s s i o n . The technique o f loosening c i t r u s f r u i t s w i t h a b s c i s s i o n chemicals can i n f l u e n c e e s s e n t i a l o i l composition and degrade the f l a v o r o f the orange j u i c e (97, 9 8 ) . Q u a n t i t a t i v e a n a l y s i s of the major v o l a t i l e compounfls o f cold-pressed orange o i l showed t h a t o i l s from a b s c i s s i o n chemical t r e a t e d , b a r e l y mature, oranges contained l e s s l i n a l o o l and more * < - s i n e n s a l , c i t r o n e l l a l , dodecanal and valencene than o i l s from the unsprayed f r u i t . In o i l s from mature f r u i t ( 9 9 ) , d i f f e r e n c e s could not be det e c t e d and the composition was s i m i l a r t o t h a t o f the b a r e l y mature c h e m i c a l l y t r e a t e d oranges. I t was concluded t h a t abs c i s s i o n chemicals which i n j u r e the f r u i t a c c e l e r a t e maturation (98). Postharvest techniques and t h e i r i n f l u e n c e upon q u a l i t y Degreening, washing, and grading. The use o f ethylene t o remove c h l o r o p h y l l from the r i n d o f c i t r u s f r u i t s i n order t o expose the orange, orange-red, r e d , or y e l l o w pigments i s p r a c t i c e d e x t e n s i v e l y . This i s p a r t i c u l a r l y t r u e i n s u b t r o p i c a l c i t r u s regions where f r u i t maturation u s u a l l y precedes the low temperatures necessary t o remove c h l o r o p h y l l from the p e e l . Q u a l i t y based on eye appeal i s enhanced e x t e n s i v e l y by such a treatment. Understandably but i l l o g i c a l l y , green c o l o r w i t h i n the r i n d represents immaturity t o consumers and, t h e r e f o r e , they are r e l u c t a n t t o purchase the product. I t has been reported t h a t green c o l o r i s the major reason f o r low pack-outs i n F l o r i d a c i t r u s (100). The degreening treatment does not improve e a t i n g q u a l i t y b u t , on the c o n t r a r y , i t c o n t r i b u t e s to p h y s i o l o g i c a l d i s o r d e r s , senescence, and losses from decay (101). However, because o f the consumer's expectations t h a t oranges and mandarins are o r a n g e - c o l o r e d , lemons and g r a p e f r u i t are



200


y e l l o w and limes are green, research e f f o r t s continue i n an e f f o r t to improve the c o l o r q u a l i t y c h a r a c t e r i s t i c o f each c u l t i v a r and type. I f performed c o r r e c t l y , degreening does not harm the i n t e r n a l q u a l i t y of c i t r u s f r u i t (98, 102). U n f o r t u n a t e l y , c r i t i c a l a t t e n t i o n to the c o n d i t i o n s necessary f o r proper degreening i s not always g i v e n . Since degreening never improves i n t e r n a l q u a l i t y but only the e x t e r n a l appearance o f the r i n d , only f r u i t of proper m a t u r i t y and i n t e r n a l q u a l i t y should be degreened. C i t r u s f r u i t s as they mature on the t r e e do not produce n a t u r a l c o l o r u n i f o r m l y , t h e r e f o r e , e a r l y i n the season, much v a r i a b i l i t y in color exists. In such i n s t a n c e s , a l l f r u i t , regardless of c o l o r , are held i n the degreening room u n t i l f r u i t of the greenest c o l o r has degreened. Spot p i c k i n g of f r u i t w i t h the best c o l o r break e l i m i n a t e s the need f o r excessive degreening time which occurs i f f r u i t of mixed c o l o r are harvested. Losses during degreening of tangerines can be reduced by spot p i c k i n g f o r c o l o r (103). S o r t i n g o f f r u i t on the b a s i s of c o l o r a f t e r harvest i s a l s o another technique a v a i l a b l e to reduce degreening time (104, 105). F r u i t which may regreen on the t r e e , such as V a l e n c i a oranges, are d i f f i c u l t to degreen (101). There are numerous reviews d e s c r i b i n g degreening (101, 106, 107, 108, 109, 110, 111, 112, 113). The most common procedure i n v o l v e s continuous metering of ethylene i n t o a room exposing f r u i t t o a c o n c e n t r a t i o n o f 1 to 20 ul ethylene/1 of a i r f o r 1 to as many as 3 days. Increased concentrations of ethylene w i l l not shorten the degreening t i m e . Humidities are maintained at l e v e l s from about 85 to 95% and temperatures range from 21.1 to 30°C, depending upon geographical areas (114, 115, 116). One exception to t h i s procedure i s p r a c t i c e d i n Japan where f r u i t are exposed to a high i n i t i a l c o n c e n t r a t i o n of 1000 ul ethylene/ 1 of a i r f o r 15 hours and then removed t o ambient c o n d i t i o n s (117, 118). Degreening continues f o r the f o l l o w i n g 2 or 3 days depending on c u l t i v a r . V a r i a t i o n s from these procedures during degreening which cause delays i n removal of c h l o r o p h y l l or excessive moisture l o s s can reduce f r u i t q u a l i t y . The most r a p i d r a t e of removal o f c h l o r o p h y l l occurs at the higher tempe r a t u r e s , but w i t h r e l a t i v e l y l i t t l e synthesis of c a r o t e n o i d s . A d i f f e r e n t degreening procedure has been adopted r e c e n t l y i n I s r a e l (106, 119). I n t e r m i t t e n t exposure of f r u i t to ethylene and heat i n 12 hour c y c l e s a t low rates o f v e n t i l a t i o n caused decreased r e s p i r a t i o n r a t e s , l e s s peel i n j u r y and r o t and maint a i n e d the f r u i t at a higher r e l a t i v e humidity. Under these c o n d i t i o n s of low v e n t i l a t i o n , carbon d i o x i d e concentrations reached l e v e l s of 2.5 to 5.0%, which d i d not i n t e r f e r e w i t h c h l o r o p h y l l removal as long as oxygen l e v e l s were adequate (120). Oxygen concentrations below 10% caused a reduction i n the degreening r a t e (121). Other workers have reported t h a t inadequate v e n t i l a t i o n rates a l l o w i n g an excess of 1% carbon d i o x i d e accumulation w i l l i n t e r f e r e w i t h the degreening process (108, 109).



10.

BROWN

Fruit

Handling

and Decay

Control

201

Q u a l i t y o f lemons r e p o r t e d l y was improved by degreening which increased the j u i c e q u a n t i t y (122). Ethylene degreening p r i o r to c o l d storage reduced c h i l l i n g i n j u r y of green-colored g r a p e f r u i t . However, ethylene tended t o i n c r e a s e c h i l l i n g i n j u r y o f f u l l y c o l o r e d y e l l o w g r a p e f r u i t (123). Exposure o f c i t r u s f r u i t s t o ethylene has been shown t o increase the i n c i d e n c e of stem-end r o t caused p r i m a r i l y by D_. n a t a l e n s i s (113, 124, 125, 126, 127). Higher than recommended ethylene concentrât!oni"T75, 106, 116, 128, 129) and temperature (116) and an increase i n degreening d u r a t i o n (116, 125) caused s i g n i f i c a n t increases i n stem-end r o t . Anthracnose, caused by £. g l o e o s p o r i o i d e s , i s a s e r i o u s disease o f s p e c i a l t y c i t r u s hybrids such as Robinson, Lee, Nova, and Page (130, 131), when f r u i t are exposed t o e t h y l e n e . Incidence was r e l a t e d d i r e c t l y to length o f degreening (130), ethylene c o n c e n t r a t i o n (132, 133), and f r u i t c o l o r (133, 134). The occurrence o f mold caused by P é n i c i l l i u m d i g i t a t u m Sacc. i s s i g n i f i c a n t l y reduced by degreening under F l o r i d a c o n d i t i o n s (135) where the temperature i s held a t 30°C. Under these c o n d i t i o n s , growth o f the organism i s s i g n i f i c a n t l y reduced and l i g n i f i c a t i o n o f the i n j u r e d e p i c a r p at the high temperatures and r e l a t i v e h u m i d i t i e s i s encouraged (136). Once l i g n i f i c a t i o n i s i n i t i a t e d , entry o f the fungus i s impeded. Normally, f r u i t are not washed before degreening because washing r e t a r d s the loss o f c h l o r o p h y l l (108). Jahn (137) r e ported t h a t washing had l i t t l e e f f e c t on c h l o r o p h y l l l o s s during degreening but c a r o t e n o i d s y n t h e s i s was s i g n i f i c a n t l y reduced by washing before degreening. Carotenoid s y n t h e s i s was reduced by l e s s brushing than was r e q u i r e d t o clean the f r u i t , but "over b r u s h i n g " had l i t t l e f u r t h e r e f f e c t . Washing before degreening i n t e r f e r r e d w i t h c o l o r development i n orange and g r a p e f r u i t more so than lemons and mandarins (138). Several b e n e f i t s from washing before degreening would be gained i f i t were not f o r the degreening problem. Processes which f o l l o w washing, such as grading o r c o l o r s o r t i n g , would be more e f f e c t i v e i f done before degreening (137). Washing before degreening has been shown t o c o n t r i b u t e s u b s t a n t i a l l y t o decay c o n t r o l (131, 138) by removing propagules o f JJ. n a t a l e n s i s and £. g l o e o s p o r i o i d e s from the f r u i t surfaces and, thereby, p r e venting i n f e c t i o n during o r f o l l o w i n g degreening (131, 132). Damage t o c i t r u s peel due to the a c t i o n o f ethylene has been r e p o r t e d , p a r t i c u l a r l y on mandarin types (109, 117), and c e r t a i n d i s o r d e r s such as o l e o c e l l o s i s (106) and r i n d s t a i n i n g (42) have been i n c r e a s e d . A burn o f Temples during degreening (125) has been shown t o be suppressed by a s u f f i c i e n t l y high r e l a t i v e humidity ( 7 5 ) . Under extremely high ethylene concent r a t i o n s (200 ul/1) and exposure f o r long periods o f time (4 weeks), s t i c k i n e s s o f the r i n d o f Marsh g r a p e f r u i t has been r e ported (139). Synthesis o f n a t u r a l wax a f t e r harvest i s s t i m u l a t e d by ethylene (140).



202


Improved c o l o r of degreened f r u i t was obtained when i t was discovered t h a t ethylene i n the form of the gas or ethephon s t i m u l a t e d c a r o t e n o i d s y n t h e s i s (141, 142, 143, 144) but at temperatures w e l l below 30°C. This high temperature caused r a p i d c h l o r o p h y l l removal but d i d not s t i m u l a t e continued c a r o t enoid synthesis and a c t u a l l y i n h i b i t e d accumulation of B - c i t r a u r i n (142, 143). C r y p t o x a n t h i n , Β - c i t r a u r i n , and to a l e s s e r e x t e n t , v i o l a x a n t h i n , accumulated i n the e p i c a r p at temperatures of 15-25°C. The y e l l o w pigments, trans-and c i s - v i o l a x a n t h i n i n creased l e s s than orange or reddish-orange pigments. Levels of ethylene r e q u i r e d f o r optimum carotenoid synthesis decreased be low 10 ul/1 o f a i r as temperatures were lowered from 30°C to 15°C at 5°C increments (143). Ethylene caused some increase i n r e s p i r a t i o n r a t e , a b s c i s s i o n of the c a l y x , and an e f f e c t on aroma of the f r u i t , but no e f f e c t on percentage s o l u b l e s o l i d s , a c i d , or c o l o r of the j u i c e (143). s t i m u l a t i o n of carotenoid synthesis could a l s o be achieved w i t h postharvest a p p l i c a t i o n of ethephon (142, 144). To achieve the improved f r u i t c o l o r r e s u l t i n g from c a r o t e n o i d s y n t h e s i s , f r u i t had to be held longer than the 1 to 3 days normally needed to remove c h l o r o p h y l l at higher temperatures (142, 143, 144). U n f o r t u n a t e l y , wastage due to decay can be excessive during periods of 8-10 days or more r e q u i r e d f o r c o l o r development under commercial c o n d i t i o n s . In an e f f o r t to reduce degreening time w i t h ethylene or to replace i t s use, postharvest a p p l i c a t i o n s of ethephon e i t h e r alone or i n combination w i t h ethylene have been evaluated (14, 145, 146, 147, 148, 149, 150). In c e r t a i n i n s t a n c e s , p o s t harvest a p p l i c a t i o n s of ethephon to green-colored f r u i t to achieve degreening during t r a n s i t would be d e s i r a b l e . Results w i t h t h i s procedure may be inadequate since waxing i n some s t u d i e s and w i t h c e r t a i n c u l t i v a r s has reduced the degreening a c t i o n of ethephon (146, 149, 151). Ethephon has had no appre c i a b l e e f f e c t on changes i n percentage j u i c e , c i t r i c a c i d , t o t a l s o l u b l e s o l i d s , vitamin C or pH (152). A c o n c e n t r a t i o n of 5000 ul ethephon/1 caused r i n d i n j u r i e s to lemons and delayed degreening of Clementine mandarins and Shamouti oranges (145). In g e n e r a l , postharvest a p p l i c a t i o n s of ethephon have not proved more e f f e c t i v e or p r a c t i c a l under commercial c o n d i t i o n s than the standard ethylene degreening p r a c t i c e . To remove the green c o l o r from lemons, the standard F l o r i d a p r a c t i c e i s to hold unwashed f r u i t (washing r e t a r d s c o l o r de velopment) at 15.6°C and high r e l a t i v e humidity u n t i l the c h l o r o p h y l l i s removed and the y e l l o w c o l o r predominates (126). This procedure requires 2 to 3 weeks during which time j u i c e y i e l d and c i t r i c a c i d increase (153). In an e f f o r t to speed up the process, ethephon or standard degreening p r a c t i c e s have been used but these u s u a l l y enhance decay, p a r t i c u l a r l y stem-end r o t (126, 148, 150, 153). Degreening was achieved w i t h standard degreening p r a c t i c e s i f mature f r u i t were t r e a t e d w i t h an e f f e c -


10.

BROWN

Fruit

Handling

and

Decay

Control

203

t i v e f u n g i c i d e before exposure to ethylene to c o n t r o l decay (154, 155). Chemicals, p a r t i c u l a r l y 2 - ( 4 - c h l o r o p h e n y l t h i o ) - t r i e t h y l a m i n e (CPTA) and some r e l a t e d compounds have been a p p l i e d postharvest to c i t r u s f r u i t t o enhance c a r o t e n o i d s y n t h e s i s (22, 2£, 151, 152, 156, 157, 158, 159). The m a t e r i a l CPTA, which has been evaluated most e x t e n s i v e l y , p r i n c i p a l l y s t i m u l a t e s the red l y c o pene c a r o t e n o i d which i s not a normal pigment f o r c i t r u s . There f o r e , i t s p r a c t i c a l use appears l i m i t e d (157). The compound 2 , 4 ' - d i c h l o r o - l - c y a n o e t h a n e s u l p h o n a n i l i d e a p p l i e d p r e - or p o s t harvest s t i m u l a t e s r a p i d and uniform removal of c h l o r o p h y l l (26, 160) i f f r u i t are subjected to l i g h t a f t e r treatment. In dark ness, i t does not serve as a degreening agent, but i t does i n t e r f e r e w i t h ethylene degreening. Since i t s mode of a c t i v i t y appears somewhat d i f f e r e n t to t h a t of e t h y l e n e , i t i s speculated that a degreening system might be developed without the d e t r i mental senescence a c t i o n a s s o c i a t e d w i t h ethylene (26). One o f the i n i t i a l processes i n the handling of c i t r u s f r u i t on the packing l i n e i s to remove f r u i t u n s u i t a b l e f o r f r e s h consumption d i v e r t i n g i t to p r o c e s s i n g . G e n e r a l l y , those f r u i t removed because of s i z e , c o l o r , or blemishes have l i t t l e i n f l u e n c e on the q u a l i t y of processed products. However, i t has been suggested t h a t e a r l y season small s i z e d f r u i t of l e s s matu r i t y or l a t e season o v e r s i z e d f r u i t of poor q u a l i t y could a f f e c t the processed product (161).


1

Decay c o n t r o l techniques. Fungicides are commonly a p p l i e d to c i t r u s f r u i t s to p r o t e c t them from decay caused by numerous f u n g i . U n l i k e many f r u i t s , healthy p o r t i o n s of decaying c i t r u s f r u i t s are normally not salvaged, and any decay of a f r u i t means t h a t the e n t i r e f r u i t i s d i s c a r d e d . Postharvest f u n g i c i d e s are u t i l i z e d t o improve keeping q u a l i t y . These chemicals appear t o have l i t t l e i n f l u e n c e on i n t e r n a l q u a l i t y or n u t r i t i o n . At l e a s t i f they do, the e f f e c t i s so s u b t l e t h a t research w i t h i n t h i s area has not been j u s t i f i e d . Several e x t e n s i v e reviews on the s u b j e c t of postharvest f u n g i c i d e s have been published (162, 163, 164, 165), as have s p e c i f i c f u n g i c i d e recommendations to c o n t r o l c i t r u s decay (166, 167, 168). A p p l i c a t i o n techniques can i n f l u e n c e the e f f i c a c y of p o s t harvest f u n g i c i d e s and, t h u s , a l t e r the keeping q u a l i t y of t r e a t e d f r u i t . A p p l i c a t i o n of sodium ortho-phenylphenate (SOPP) i n a foam washer w i t h an exposure time of only 15 to 20 sec i s not as an e f f e c t i v e method as a soak or drench treatment r e q u i r i n g 2-4 min (167). However, i f proper pH c o n t r o l i s not maintained, f r u i t may be burned w i t h the soak or drench t r e a t ment (169, 170, 171). A p p l i c a t i o n s of SOPP i n wax were l e s s p h y t o t o x i c ΤΊ72). Within the l a s t 14 y e a r s , development of the benzimidazoles, t h i a b e n d a z o l e £ 2 - ( 4 ' - t h i a z o l y l ) b e n z i m i d a z o l e ^ and .benomyl {methyl 1-(butyl carbamoyl)-2-benzimidazole-carbam a t e j , has l e d to the a v a i l a b i l i t y of f u n g i c i d e s w i t h high



204


l e v e l s of a c t i v i t y against the major decay pathogens. Litera t u r e p e r t a i n i n g to the a p p l i c a t i o n of the benzimidazoles and techniques which a l t e r t h e i r e f f i c a c y has r e c e n t l y b e e n reviewed (173). A p p l i c a t i o n of the benzimidazoles by suspension i n water emulsion wax or by d i s s o l v i n g i n a hydrocarbon-soluble ( s o l v e n t ) wax has not u s u a l l y provided as good decay c o n t r o l as when the m a t e r i a l s are a p p l i e d i n water. N o n a v a i l a b i l i t y o f the f u n g i c i d e at the i n f e c t i o n s i t e because of i n c o r p o r a t i o n w i t h i n the wax and v a r i a b l e coverage with the wax a p p l i c a t i o n , p a r t i c u l a r l y under the c a l y x f o r stem-end r o t c o n t r o l , have been suggested as reasons f o r reduced decay c o n t r o l . Less f u n g i c i d a l a c t i v i t y by benomyl may occur i n a l k a l i n e water waxes where the m a t e r i a l de grades to methyl 2-benzimidazole carbamate (MBC) and 1,2,3,4t e t r a h y d r o - 3 - b u t y l - 2 , 4 - d i o x o - S - t r i a z i n o l a j benzimidazole (STB) (174, 175), which has very weak, i f any, f u n g i c i d a l a c t i v i t y (164). A p p l i c a t i o n s of TBZ, benomyl and MBC i n wax f o r sporu l a t i o n c o n t r o l of P. d i g i t a t u m to reduce s o i l a g e (surface con tamination of healthy f r u i t by mold spores) have shown t h a t benomyl i s the most e f f e c t i v e of the three m a t e r i a l s (167, 175, 176). Benomyl penetrated the peel more e f f i c i e n t l y than MBC, forming a f u n g i s t a t i c b a r r i e r i n the e p i c a r p t h a t prevented e r u p t i o n of the hyphae of F\ d i g i t a t u m through the epidermis (175). Preharvest a p p l i c a t i o n s of benomyl to V a l e n c i a oranges f o r the c o n t r o l of post-harvest decay s i g n i f i c a n t l y reduced aging ( s h r i v e l i n g of the r i n d a t the stem-end) (52). Vapor-phase fumigants are used f o r c i t r u s decay c o n t r o l , diphenyl being the most e f f e c t i v e and commonly used m a t e r i a l . The undesirable odor imparted to t r e a t e d f r u i t d i s s i p a t e s w i t h i n a few days a f t e r removal of the f r u i t from the diphenyl atmo sphere. Control of stem-end r o t s caused by A. c i t r i , D. n a t a l e n s i s , and J P . c i t r i w i t h postharvest a p p l i c a t i o n s of the growth r e g u l a t o r s 2, 4-D and, o c c a s i o n a l l y , 2,4,5-T i s a t t r i b u t e d to p r e s e r v a t i o n of the green button and prevention of a b s c i s s i o n (106, 177, 178, 179, 180, 181, 182). Freshness and r e t a r d a t i o n of c o l o r changes a s s o c i a t e d w i t h senescence are b e n e f i t s of the treatment (183, 184). G i b b e r e l l i c a c i d a p p l i e d a f t e r harvest was a l s o reported to reduce decay of lemons (183), but i t s p r i mary e f f e c t i s to r e t a i n c h l o r o p h y l l (183, 185ΤΓ Total s o l u b l e s o l i d s , a c i d i t y and a s c o r b i c a c i d were not s i g n i f i c a n t l y i n fluenced by 2,4-D (184) or GA (183, 184). Treatments of c i t r u s f r u i t s to c o n t r o l decay fungi which leave no chemical residues would be d e s i r a b l e . E r a d i c a t i o n of i n c i p i e n t i n f e c t i o n s of decay fungi w i t h heat treatments and gamma r a d i a t i o n have been t r i e d . Immersion of c i t r u s f r u i t s i n water at 48 C f o r 2-4 min to c o n t r o l species of Phytophthora has been shown to p h y s i o l o g i c a l l y weaken lemons, i n some i n stances, and increase t h e i r s u s c e p t i b i l i t y to other p a t h o l o g i c a l diseases during storage (186). Decay caused by I P . d i g i t a t u m , P. c i t r i , and D. n a t a l e n s i s was reduced by t r e a t i n g oranges a t



10.

BROWN

Fruit

Handling

and

Decay

Control

205

53°C f o r 5 min (187, 188), but p h y s i o l o g i c a l breakdown of the r i n d was i n c r e a s e d . Cold t u r g i d lemons r e q u i r e d s l i g h t dehydration before immersion to reduce o l e o c e l l o s i s (189). T r e a t ment a t elevated temperatures to enhance decay c o n t r o l w i t h SOPP increased the i n c i d e n c e of o l e o c e l l o s i s and darkened i n j u r i e s of the r i n d (169). Use of gamma rays to destroy pathogens i n e s t a b l i s h e d l e s i o n s w i t h i n the f r u i t has g e n e r a l l y been unsuccessful. Dosages r e q u i r e d to e r a d i c a t e or r e t a r d c e r t a i n pathogens, p a r t i c u l a r l y the stem-end r o t fungi D i p l o d i a and A l t e r n a r i a , g e n e r a l l y caused adverse e f f e c t s to the f r u i t . These were mani f e s t e d as damage to the r i n d (190, 191, 192), o f f - f l a v o r s (191, 193, 194) and l o s s i n i n t e r n a l q u a l i t y and weight (191, 195). R e s p i r a t i o n r a t e s (191, 195) and ethylene evolution~TT%T"â"re increased by gamma r a d i a t i o n treatments. There i s a marked l o s s i n a s c o r b i c a c i d i n lemons t r e a t e d w i t h 200 Krad or above (195), but not i n Washington Navel oranges t r e a t e d w i t h 200 Krad or l e s s (191). A thorough review of the e f f e c t of gamma r a d i a t i o n on c i t r u s f r u i t s i s a v a i l a b l e i n the l i t e r a t u r e (194). Waxing. S o - c a l l e d wax coatings are normally a p p l i e d to c i t r u s f r u i t s to r e p l a c e n a t u r a l wax removed i n washing, to impart gloss to increase consumer a p p e a l , and to reduce s h r i n k age from l o s s of moisture. Both n a t u r a l waxes and s y n t h e t i c r e s i n s are used and are a p p l i e d as aqueous emulsions or ( f o r the r e s i n s ) as s o l u t i o n s i n an organic s o l v e n t . Some a d d i t i o n a l e f f e c t s from wax a p p l i c a t i o n s have been observed. Wax coatings lowered i n t e r n a l oxygen and r a i s e d carbon d i o x i d e l e v e l s (197, 198, 199, 200, 201) and t h i c k e r than normal a p p l i c a t i o n s may cause ethanol accumulation (197, 202, 203) and o f f - f l a v o r s . A thickness of c o a t i n g which reduced the weight l o s s to 50% of t h a t of untreated f r u i t produced i n t e r n a l anaerobic c o n d i t i o n s and o f f - f l a v o r s (197, 204). Ethanol b u i l d - u p i n j u i c e and o f f f l a v o r s occurred a f t e r m u l t i p l e coatings of water wax or s o l v e n t type wax; l e s s ethanol accumulation and no o f f - f l a v o r s were noted i n polyethylene-coated f r u i t s (203). Reductions i n c h i l l ing i n j u r y of g r a p e f r u i t (205, 206), p i t t i n g of V a l e n c i a oranges (207), black spot (Guignardia c i t r i c a r p a K i e l y ) of V a l e n c i a oranges (208), decay of lemons"Tl83), and an i n c r e a s e i n c h i l l ing i n j u r y of limes (209) has been obtained w i t h wax a p p l i c a t i o n s . Waxing w i t h aqueous emulsion waxes has been shown to r e t a r d degreening (210). Fumigation. Many c o u n t r i e s importing c i t r u s f r u i t s r e q u i r e t h a t the f r u i t be t r e a t e d to e r a d i c a t e eggs, l a r v a e , and pupae of f r u i t f l i e s so as to prevent t h e i r i n t r o d u c t i o n i n t o u n i n f e s t e d areas. Treatment f o r the e r a d i c a t i o n of a t l e a s t 5 species of 3 genera of f r u i t f l i e s has been r e p o r t e d . Ethylene dibromide (EDB) and o c c a s i o n a l l y methyl bromide, g e n e r a l l y a p p l i e d as fumigants, have been u t i l i z e d most e x t e n s i v e l y f o r t h i s purpose. I f c a r e f u l handling and proper treatment are not



206


f o l l o w e d , r i n d of c i t r u s f r u i t s can be d i s c o l o r e d or p i t t e d by the fumigation treatment (211, 212, 213, 214, 215, 216, 217, 218). Fumigation damage r e s u l t i n g i n r i n d i n j u r y may be assoc i a t e d with p r i o r p r e c o o l i n g before treatment (217) or w i t h i n adequate v e n t i l a t i o n a f t e r fumigation (212, 214, 217, 219). R e f r i g e r a t i o n should be delayed f o r at l e a s t 24 hours a f t e r treatment (217). Injury to Marsh g r a p e f r u i t and Shamouti and V a l e n c i a oranges was due to the p e r s i s t e n c e of residues of the fumigant i n the f r u i t peel (212). The desorption r a t e during a e r a t i o n increased w i t h temperature. Incidence of peel i n j u r y was highest i n f r u i t s t o r e d at low temperature or wrapped i n polyethylene bags, probably due to prolonged a c t i o n of the EDB residues on the p e e l . Storage of fumigated f r u i t i n an atmosphere c o n t a i n i n g an increased c o n c e n t r a t i o n of carbon d i o x i d e delayed the appearance o f damage. Fumigation i n j u r y was e n hanced by the presence of diphenyl impregnated i n pads (217). Ethylene degreened g r a p e f r u i t were s l i g h t l y more s e n s i t i v e to EDB fumigation than non-degreened f r u i t (220). R e s p i r a t i o n of lemon and orange f r u i t s was s t i m u l a t e d by EDB exposure and was p r o p o r t i o n a l to the dosage l e v e l (221). Treated f r u i t s a l s o evolved more e t h y l e n e , p a r t i c u l a r l y those e x h i b i t i n g i n j u r y (211). The e f f e c t of chamber load on EDB absorption and r i n d i n j u r y showed t h a t reducing the l o a d i n g r a t e from 30 to 15% i n creased EDB absorption considerably and often caused development of severe r i n d i n j u r y (215). Increasing loading rates from 45 to 60% had l i t t l e e f f e c t on absorption of EDB by the f r u i t . N u t r i t i o n a l value of lemons, as determined by percentage j u i c e and s o l u b l e s o l i d s , c i t r i c a c i d , pH, and a s c o r b i c a c i d , was not a f f e c t e d by fumigation (221). The a p p l i c a t i o n of TBZ to c i t r u s f r u i t i n the wax coating e i t h e r before or a f t e r fumigation markedly reduced the i n c i d e n c e of EDB peel i n j u r y (222). A p p l i c a t i o n s of TBZ i n a water suspension or i n a water suspension followed by the wax c o a t i n g which d i d not c o n t a i n the f u n g i c i d e d i d not e f f e c t i v e l y reduce the incidence of the i n j u r y . EDB r e p o r t e d l y was s t a b l e and nonreactive with the c o n s t i t u e n t s of the t i s s u e s of V a l e n c i a and navel oranges, and lemons (219). Handling P r a c t i c e s . Methods used i n the packinghouse to prepare f r u i t f o r the f r e s h market may a l s o i n f l u e n c e the s h e l f l i f e and i n t e r n a l q u a l i t y . Processing Dancy tangerines on the packinghouse l i n e c u r t a i l e d the subsequent l i f e of the f r u i t , p a r t i c u l a r l y when degreened (103), Rind breakdown i n oranges was shown to increase w i t h processing (223). Washing, c o l o r adding, and waxing treatments had l i t t l e e f f e c t upon the t o t a l s o l u b l e s o l i d s , t o t a l a c i d s , or v i t a m i n C content of the j u i c e . Taste t e s t s , however, i n d i c a t e d t h a t f l a v o r was never improved, and i n some l o t s r e c e i v i n g the f u l l packinghouse treatment, t a s t e was unmistakably impaired (223). Dropping of F l o r i d a g r a p e f r u i t during h a r v e s t i n g (64) or of Satsuma mandarins during the packing process (224) was shown to decrease firmness during



10.

BROWN

Fruit

Handling

and Decay

Control

207

storage. The r e s p i r a t i o n r a t e o f c i t r u s f r u i t i s increased by rough handling (81, 201, 224, 225), and handling a l s o hastened y e l l o w i n g o f Persian~Umes~T8l7T~ In the case o f dropped Satsuma mandarins held i n storage (224), the r a t i o of dehydroascorbic a c i d to t o t a l a s c o r b i c a c i d i n the pulp increased i n p r o p o r t i o n to the number o f times the f r u i t were dropped. Most types of mechanical i n j u r y t o mandarins were produced upon dropping impact, compression, and abrasion (226). Two major f a c t o r s c o n t r o l l i n g breakdown of j u i c e sacs were dropping height and compression (227). Several postharvest treatments to c i t r u s f r u i t s have been t e s t e d i n an e f f o r t to improve the q u a l i t y o f the e x t r a c t e d j u i c e . Bruemmer and Roe subjected c i t r u s f r u i t s to anaerobic c o n d i t i o n s f o r periods of 20 t o 32 hours a t 32.2 to 43°C (228, 229). This treatment reduced the t i t r a t a b l e a c i d i t y and i n creased the B r i x - a c i d r a t i o by about 10%. The decrease i n a c i d i t y was accompanied, however, by a 2 0 - f o l d increase i n ethanol (229). Since the s o l u b l e s o l i d s - a c i d r a t i o i s a major c r i t e r i o n of c i t r u s j u i c e q u a l i t y , t h i s procedure, i f p e r f e c t e d , could a l l o w e a r l i e r harvesting of f r u i t and a more c o n s i s t e n t supply of f r u i t during the processing season. Bitterness of products from navel oranges, lemons, and g r a p e f r u i t i s r e l a t e d to l i m o n i n content. A 3-hour treatment o f f r u i t w i t h 20 ul ethylene/1 of a i r lowered the limonin content, reduced b i t t e r ness, and the j u i c e was judged more p a l a t a b l e than j u i c e from untreated f r u i t (230). Storage and Q u a l i t y of C i t r u s

Fruits

Cold Storage. C i t r u s f r u i t s may be stored to provide a source o f f r u i t a t times other than during the normal harvesting season, to hold f r u i t u n t i l a market i s a v a i l a b l e , or w h i l e f r u i t i s i n t r a n s i t to a d i s t a n t market. U n l i k e deciduous f r u i t s , c i t r u s does not undergo r a p i d chemical or p h y s i c a l changes a f t e r harvest. C i t r u s f r u i t s are n o n - c l i m a c t e r i c , hence, they do not r i p e n o r improve i n q u a l i t y a f t e r harvest. The only exception may be the lemon, which i s picked hard and green, and which i n creases i n j u i c e and becomes y e l l o w during normal storage periods. I f c i t r u s f r u i t s are stored under proper temperatures, h u m i d i t i e s , and atmospheres, and are marketed a f t e r a proper d u r a t i o n of s t o r a g e , the q u a l i t y of the f r u i t does not d i f f e r g r e a t l y from t h a t which e x i s t e d a t harvest. Storage of f r u i t at lowered temperatures reduces f r u i t r e s p i r a t i o n and r a t e o f growth o f decay pathogens w i t h a r e s u l t i n g p r o p o r t i o n a t e i n crease i n f r u i t storage l i f e . Since numerous reviews on the subject o f changes i n c i t r u s f r u i t s during c o l d storage have been w r i t t e n ( 1 , 231, 232, 233, 234, 235, 236, 237), d i s c u s s i o n of the t o p i c w i l l be l i m i t e d p r i m a r i l y to some o f the more recent studies. Some of the changes c h a r a c t e r i s t i c of m a t u r a t i o n , notably



208


decreasing a c i d i t y , continue a f t e r storage. The f r u i t begins to l o s e weight as soon as i t leaves the t r e e and there i s g e n e r a l l y a l o s s of s o l u b l e s o l i d s and a s c o r b i c a c i d , on the basis of the o r i g i n a l f r e s h weight of the f r u i t . I f the weight l o s s i s exc e s s i v e , these c o n s t i t u e n t s may a c t u a l l y increase i n c o n c e n t r a t i o n (233). However, some q u i t e s i g n i f i c a n t losses i n a s c o r b i c a c i d have been r e p o r t e d , p a r t i c u l a r l y w i t h lemons (238) and t a n gerines (239). Q u a l i t y of V a l e n c i a oranges stored f o r 12 and 18 weeks at 15 and 5 C, r e s p e c t i v e l y , was compared to s i m i l a r f r u i t l e f t on the t r e e (240). Storage f r u i t was d e f i n i t e l y of b e t t e r q u a l i t y . Color was b e t t e r , s i n c e regreening which occurred i n f r u i t on the t r e e d i d not occur i n storage. G r a n u l a t i o n and stem-end browning a l s o developed i n f r u i t held on the t r e e but not i n storage f r u i t . C o o l - s t o r e d f r u i t was a l s o higher i n B r i x , B r i x / a c i d r a t i o , and a s c o r b i c a c i d . Loss of f l a v o r i n storage a f t e r 24 weeks a t 15 C was a s s o c i a t e d w i t h a r a p i d d e c l i n e i n B r i x / a c i d r a t i o , a s c o r b i c a c i d , polyphenols, and f l a v o n o i d s of the j u i c e . V a l e n c i a oranges stored a t 3.3 C f o r 6 months decreased i n a c i d i t y , increased i n t o t a l s o l u b l e s o l i d s , and v a r i e d i n a s c o r b i c a c i d content (241). C i t r i c a c i d was the main a c i d i n j u i c e , malonic and m a l i c a c i d s predominated i n the r i n d of Shamouti oranges stored 3 months at 17 C (242). With a g i n g , m a l o n i c , s u c c i n i c and a d i p i c a c i d s i n creased i n r i n d and j u i c e , but c i t r i c and m a l i c a c i d s decreased i n the j u i c e . The authors (242) suggest t h a t malonic a c i d could serve as an i n d i c a t o r of f r u i t t i s s u e senescence i n s t o r a g e , because accumulation of the a c i d w i t h i n the r i n d begins a t f r u i t m a t u r i t y , and increased t h r e e - f o l d during three months of p o s t harvest storage. I t has been r e c e n t l y suggested (243) t h a t ethanol may a l s o be an i n d i c a t o r of f r u i t c o n d i t i o n s s i n c e i t showed g r e a t e r changes during storage and subsequent holding than d i d acetaldehyde, t o t a l s o l u b l e s o l i d s , t i t r a t a b l e a c i d , or pH. Ethanol increased more i n g r a p e f r u i t stored f o r 3 months a t 1.0 C than at 4.5 or 10°C. In oranges, ethanol increased more a t 10°C than a t 4.5 or 1.0 C. Ethanol content i n j u i c e of Hamlin, P i n e apple and V a l e n c i a oranges and Marsh g r a p e f r u i t increased w i t h decreasing oxygen ( 0 ) c o n c e n t r a t i o n i n CA storage and w i t h wax a p p l i c a t i o n s (202). The ethanol content of j u i c e of Marsh grapef r u i t increased w i t h i n c r e a s i n g carbon d i o x i d e (C0 ) c o n c e n t r a t i o n s from 10 to 30%, w i t h length of time of exposure to C 0 , and w i t h t o t a l time of storage. The acetaldehyde content o f the j u i c e , although much lower than the ethanol c o n t e n t , increased i n a s i m i l a r manner (244). Under these various storage c o n d i t i o n s , the ethanol content was apparently i n s u f f i c i e n t to a f f e c t f l a v o r s i g n i f i c a n t l y . The c o n d i t i o n of f r u i t during c o l d storage (245) was estimated by continuously monitoring the C 0 produced hourly/ kg of f r u i t and c a l c u l a t i n g the r e l a t i v e increase i n the r e s p i r a t o r y i n t e n s i t y . Increases i n r e s p i r a t i o n were due to i n f e c t e d f r u i t plus the e f f e c t of ethylene emanation on metabolism of healthy f r u i t . 2

2

2

2



10.

BROWN

Fruit

Handling

and Decay

209

Control

C h i l l i n g i n j u r y . A major problem w i t h c o l d storage of c i t r u s f r u i t s i s t h a t o f c h i l l i n g i n j u r y o r p i t t i n g , which occurs i n c h i l l - s e n s i t i v e f r u i t s such as g r a p e f r u i t , lemon, and lime a t temperatures of 5-10 C. Eaks (42) reported t h a t limes had to be stored a t 5 C to r e t a i n green c o l o r , but c h i l l i n g i n j u r y d e v e l oped i n about 4-5 weeks. Storage a t 10°C e l i m i n a t e d the c h i l l i n g i n j u r y problem, but f r u i t became y e l l o w - c o l o r e d a f t e r 2-3 weeks. Several techniques i n handling c i t r u s f r u i t s , p r i n c i p a l l y grapef r u i t , have been u t i l i z e d to m i t i g a t e the incidence of c h i l l i n g i n j u r y . Exposure of f r u i t to high r e l a t i v e humidity (95-100%) f o r several days before storage (123, 246) or a t lower moisture l e v e l s (curing) f o r 1 to 2 weeks T247, 248, 249) have reduced incidence of the d i s o r d e r . Waxing has a l s o been shown to have a f a v o r a b l e e f f e c t (250, 251). I n t e r m i t t e n t warming during the storage period has"âTso~Bêen s u c c e s s f u l (252, 253). C h i l l i n g i n j u r y was reduced by removing f r u i t p e r i o d i c a l l y from storage a t 4.4°C to 21.1°C f o r 8 hours during an 8-week period (253). Treatment w i t h ethylene before c o l d storage (123, 249) i s another technique f o r c o n t r o l , however, i t was more e f f e c t i v e on greenc o l o r e d f r u i t (123). C h i l l i n g i n j u r y of limes was markedly r e duced by storage i n a p a r t i a l vacuum a t 220 mm of Hg (123), and some i n f l u e n c e from growth r e g u l a t o r s (benzyladenine, GA, 2,4-D) a p p l i e d p r e - or postharvest has been observed (50). Treatments w i t h high l e v e l s of 0 0 (40%) f o r up to seven days a t 21.1°C s i g n i f i c a n t l y reduced c h i l l i n g i n j u r y (247). Success using C 0 treatments i n a d d i t i o n a l studies g e n e r a l l y a t lower C 0 l e v e l s has been obtained (254, 255, 256, 257, 258). Fungicides a p p l i e d f o r the c o n t r o l o f decay fungi unexpectedly reduced c h i l l i n g i n j u r y (251, 258, 259, 260). Control w i t h TBZ and benomyl g e r s i s t e d during 16 weeks storage of g r a p e f r u i t a t 2, 5, and 8 C (251}. TBZ was more e f f e c t i v e than benomyl and treatments were most e f f e c t i v e when the m a t e r i a l s were incorporated i n t o the wax. The e f f e c t of TBZ was enhanced by i n c r e a s i n g c o n c e n t r a t i o n and r e s i d u e s , but the e f f e c t i v e n e s s of benomyl was not improved w i t h increased c o n c e n t r a t i o n s . Reduced c h i l l i n g i n j u r y of g r a p e f r u i t w i t h the use o f benomyl was a l s o observed by McCornack (261), but use of the f u n g i c i d e diphenyl s i g n i f i c a n t l y increased c h i l l i n g i n j u r y . F o r t u n a t e l y , the benzimidazoles, TBZ and benomyl, are used e x t e n s i v e l y on c i t r u s f r u i t s f o r decay c o n t r o l and the m i t i g a t i o n of c h i l l i n g i n j u r y from t h e i r a p p l i c a t i o n provides an a d d i t i o n a l b e n e f i t . U n f o r t u n a t e l y , however, the cause of c h i l l ing i n j u r y has y e t to be d e f i n e d , and none o f these handling techniques provide complete c o n t r o l of t h i s d i s o r d e r . 2

2

2

P r e - c o o l i n g . P r e - c o o l i n g , a technique to remove f i e l d heat from c i t r u s f r u i t s , i s advised s i n c e r e f r i g e r a t i o n f a c i l i t i e s w i t h i n most t r a n s i t containers do not have s u f f i c i e n t c a p a c i t y to cool f r u i t s r a p i d l y . F r u i t i s o f t e n d e l i v e r e d from the f i e l d a t r e l a t i v e l y high temperatures. Processes w i t h i n the packinghouse such as degreening, c o l o r - a d d i n g , and drying c o n t r i b u t e f u r t h e r



210


heat to the f r u i t . P r e - c o o l i n g can be accomplished by a i r c o o l i n g or h y d r o - c o o l i n g . Forced a i r a t -2 C f o r 6 to 24 hours p r i o r to v e n t i l a t e d shipment o f Shamouti, V a l e n c i a and navel oranges and Marsh g r a p e f r u i t (262) reduced weight l o s s during simulated shipment and storage. P r e - c o o l i n g of f r u i t to temperatures below 0 C was not advised because of p o s s i b l e e f f e c t s on q u a l i t y . P r e - c o o l i n g of F l o r i d a oranges (263) i n i t i a l l y reduced decay l e v e l s but then decay l e v e l s increased during simulated s h e l f - l i f e . Water damage from hydro-cooling caused increased decay of tangerines and g r a p e f r u i t (264) and oranges (265). Decay a f t e r hydro-cooled f r u i t are allowed to come to ambient temperature, as i n markets or homes, f r e q u e n t l y exceeded t h a t of non-hydro-cooled f r u i t (266). Peel i n j u r y , p a r t i c u l a r l y of Pineapple oranges, was o f t e n increased by h y d r o - c o o l i n g . C o n t r o l l e d Atmosphere Storage. Use of c o n t r o l l e d atmosphere (CA), an atmosphere c o n t a i n i n g more CO2 and l e s s 0 than a i r , to maintain the q u a l i t y of c i t r u s during storage has g e n e r a l l y been no more e f f e c t i v e than c o l d storage i n a i r . Several reviews of the s u b j e c t published p r e v i o u s l y cover r e s u l t s o f some o f the e a r l i e r work (1 207, 236, 237, 267, 268, 269). Various r e s u l t s have been obtained and i n d i c a t e t h a t f a c t o r s other than 0 and C 0 c o n c e n t r a t i o n s , such as v a r i e t y , m a t u r i t y and humidity may be i n v o l v e d . Decay i s o f t e n enhanced w i t h c e r t a i n CA storage c o n d i t i o n s (268, 270, 271, 272), d i s o r d e r s of the r i n d may be i n creased (209, 270, 27T, 273) and o f f - f l a v o r s may develop (271, 274). However, some improvement i n keeping q u a l i t y w i t h CA storage has been r e p o r t e d . V a l e n c i a oranges held i n 15% 0 -0% C 0 f o r 12 weeks a t 1 C plus 1 week a t 21°C had higher f l a v o r r a t i n g s than s i m i l a r f r u i t held i n other c o n t r o l l e d atmospheres or i n a i r (267) A d d i t i o n o f e i t h e r 2.5 o r 5% C 0 c o n t r o l l e d aging. No marked d i f f e r e n c e s were found i n t o t a l s o l u b l e s o l i d s , t o t a l a c i d , pH, a s c o r b i c a c i d , or h e s p e r i d i n between V a l e n c i a oranges from CA storage and those from a i r (207). Less decay developed f o l l o w i n g storage of V a l e n c i a oranges a t 15 or 10% 0 w i t h 0% C 0 than when s t o r e d i n a i r (275). P i t t i n g ( c h i l l i n g i n j u r y ) o f g r a p e f r u i t was e l i m i n a t e d by CA storage at 10 C but not lower temperatures (267). C o n t r o l l e d atmosphere storage of Satsuma mandarin increased the p r o p o r t i o n of marketable f r u i t , f r u i t d e n s i t y , and c i t r i c a c i d c o n c e n t r a t i o n . Optimum c o n d i t i o n s were 1% C 0 w i t h 6-9% 0 (276). Storage of navel oranges at 15 C a t high 0 l e v e l s (40-80%) improved the orange c o l o r of the endocarp and of e x t r a c t e d j u i c e (277). Some of the most o p t i m i s t i c r e s u l t s w i t h CA storage have been reported from work w i t h lemons. B i a l e (278) i n d i c a t e d t h a t lemons may b e n e f i t from CA storage. Storage l i f e was prolonged markedly by atmosphere of 5 and 10% 0 . R e s p i r a t i o n r a t e s were reduced, c o l o r changes were r e t a r d e d , and decay, caused p r i m a r i l y by A. c i t r i , was reduced. An atmosphere of .6% 0 without C 0 was the best treatment f o r lemons a t 15.6°C (272, 279). Levels of 5 to 2

9

2

2

2

2

2

2

2

2

2

2

2

2

2


BROWN

10.

Fruit

Handling

and Decay

211

Control

8% 0 reduced decay to l e s s than t h a t i n a i r storage (279). The importance of removing e t h y l e n e , which may accumulate i n storage f a c i l i t i e s , to enhance keeping q u a l i t y was emphasized by some recent s t u d i e s (280). V a l e n c i a oranges were stored a t 10°C i n 5% C0 and 3% 0^ without and w i t h an ethylene absorbant P u r a f i l (porous alumina beads impregnated w i t h potassium permanganate). By keeping ethylene concentrations to l e s s than 0.8 ul/1 of a i r , stem-end decay caused by a species o f Fusarium, green mold, l o s s of orange f l a v o r , and development o f o f f - f l a v o r s were minimized. Other v o l a t i l e s present w i t h and without the ethylene absorber apparently had no e f f e c t on q u a l i t y . E t h y l e n e , produced i n copious q u a n t i t i e s by r o t s , enhances r e s p i r a t i o n and senescence of healthy f r u i t w i t h i n the storage f a c i l i t y (281). The importance o f ethylene removal has been i l l u s t r a t e d a l s o i n recent storage s t u d i e s of lemons i n A u s t r a l i a (282, 283, 284, 285). Lemons remained i n good c o n d i t i o n f o r up to 6 months under an atmosphere of 6-10% 0 and e s s e n t i a l l y no CO? a t 10 C w i t h continuous removal of the ethylene (285). The Tower ethylene conc e n t r a t i o n s s i g n i f i c a n t l y reduced the development o f green mold (284). Oxygen c o n c e n t r a t i o n i n the atmosphere was a l s o shown to r e g u l a t e the e f f e c t of ethylene on the r a t e of green c o l o r l o s s from lemon r i n d . An atmosphere o f 11% 0 and 6 ul/1 o f accumul a t e d ethylene caused a more r a p i d l o s s o f green c o l o r than d i d 5% 0 and 300 ul ethylene/1 of a i r . Removal of ethylene was usef u l i n m a i n t a i n i n g the green c o l o r but i t was more e f f e c t i v e when combined w i t h CA storage. By t r e a t i n g f r u i t w i t h 2,4-D and GA, both a t a c o n c e n t r a t i o n of 500 mg/1, optimum r e s u l t s were obtained i n an e t h y l e n e - f r e e CA. The 2,4-D e f f e c t i v e l y prevented senescence o f the button w h i l e the GA retarded the development of the deep y e l l o w c o l o r a s s o c i a t e d w i t h o v e r - m a t u r i t y . Attempts t o s t o r e limes i n CA o f t e n r e s u l t e d i n s c a l d - l i k e i n j u r y t o the r i n d and an i n c r e a s e i n the i n c i d e n c e o f decay (209, 272). Limes stored i n a CA of 5% 0 w i t h 7% C 0 maint a i n e d acceptable green c o l o r , but had low j u i c e c o n t e n t , t h i c k r i n d s , and a high i n c i d e n c e o f decay 286). However, limes were s u c c e s s f u l l y stored when held under low pressure (hypobaric) c o n d i t i o n s . Berg and Berg (287) reported limes were s t i l l green a f t e r 8 weeks a t 150 mm Hg ancT~15 C, whereas, 50% of c o n t r o l f r u i t s turned y e l l o w i n 10 days. Spalding (286, 288) observed t h a t T a h i t i (Persian) limes r e t a i n e d green c o l o r , j u i c e c o n t e n t , and f l a v o r acceptable f o r marketing and had a low i n c i d e n c e o f decay during storage a t a low atmospheric pressure o f 170 mm Hg f o r up to 6 weeks a t 10°C or 15.6 C and a r e l a t i v e humidity of 98-100%. Check f r u i t s turned y e l l o w w i t h i n 3 weeks a t normal atmospheric pressure. Low pressure storage d i d not prevent c h i l l i n g i n j u r y of f r u i t stored a t 2.2°C. At 21.1°C, f r u i t stored a t 170 mm Hg remained green and s u i t a b l e f o r marketing a f t e r 3-4 weeks i f t r e a t e d w i t h TBZ or benomyl f o r decay c o n t r o l . Removal o f ethylene a t low pressure was suggested to be involved i n r e t a r d a t i o n o f r i p e n i n g (287), and appears to be c r i t i c a l to 2


2

2

2

2

2

2

0


212


the success of storage of both lemons and l i m e s . Low pressures l e s s than 50 mm Hg were r e q u i r e d to r e t a r d growth of common postharvest decay fungi (289). A c t i o n was f u n g i s t a t i c r a t h e r than f u n g i c i d a l .


F r u i t Q u a l i t y as Influenced by Packaging and T r a n s p o r t a t i o n Packaging. Techniques used i n packaging and t r a n s p o r t i n g c i t r u s f r u i t s i n f l u e n c e f r u i t q u a l i t y . The package and/or cont a i n e r must p r o t e c t the f r u i t from mechanical damage and provide a f a v o r a b l e m i c r o c l i m a t e f o r the f r u i t i f q u a l i t y i s to be maintained from harvest to consumption. Various reviews on the subj e c t of packaging and t r a n s p o r t i n g c i t r u s have been published p r e v i o u s l y (250, 268, 290, 291, 292, 293, 294). T h e r e f o r e , only the major aspects as w e l l as recent developments not p r e v i o u s l y reviewed w i l l be discussed here. R e l a t i v e humidity i s c r i t i c a l l y important to the p r e s e r v a t i o n of q u a l i t y , both i n i t s i n f l u e n c e upon the f r u i t and upon decay pathogens (295). Humidity w i t h i n the package or c o n t a i n e r can vary e x t e n s i v e l y . M i c r o c l i m a t e changes occur due to t r a n s p i r a t i o n , r e s p i r a t i o n , and to changes i n ambient c o n d i t i o n s (291, 296, 297). I n t e r a c t i o n s between f r u i t and a i r temperatures when f r u i t are t r a n s f e r r e d i n t o and out of r e f r i g e r a t e d cond i t i o n s can have d r a s t i c e f f e c t s on humidity (292). High humidi t y and poor v e n t i l a t i o n i n polyethylene bags or s h r i n k - f i l m wrapped paper t r a y s have led to increased amounts of decay (290, 291, 298, 299, 300). T h e r e f o r e , p e r f o r a t i o n s w i t h i n the f i l m are required to reduce humidity and C 0 l e v e l s (301). On the other hand, f r u i t packed i n mesh bags can l o s e moisture e x c e s s i v e l y and become f l a c c i d and s h r i v e l e d (300). Decay of only one f r u i t w i t h i n a package makes i t unacceptable to the consumer, and v o l a t i l e s from decaying f r u i t w i t h i n a polyethylene f i l m bag may produce o f f - f l a v o r s i n the j u i c e of sound f r u i t s w i t h i n the same bag (302). Films possessing d i f f e r e n t p e r m e a b i l i t y to 0 and C 0 have been used to develop atmospheres and/or h u m i d i t i e s which improve q u a l i t y . C h i l l i n g - i n j u r y was reduced i n g r a p e f r u i t by packaging f r u i t under various types of f i l m s (206, 303, 304). Some recent success i n improving keeping q u a l i t y of c i t r u s f r u i t s has been obtained by wrapping i n d i v i d u a l f r u i t w i t h i n f i l m of high dens i t y p o l y e t h y l e n e . Ben-Yehoshua and co-workers (305, 306) markedly delayed d e t e r i o r a t i o n of i n d i v i d u a l l y wrapped Shamouti and V a l e n c i a oranges, Marsh g r a p e f r u i t , and Eureka lemons. Peel shrinkage, s o f t e n i n g , deformation, and l o s s of f l a v o r was delayed. Sealed f r u i t maintained the f r e s h appearance more than twice as long as c o n v e n t i o n a l l y handled f r u i t . Weight l o s s was reduced about f i v e - f o l d . R e s p i r a t o r y a c t i v i t y and ethylene production was a l s o reduced i n wrapped and sealed f r u i t . In a separate study (307), g r a p e f r u i t wrapped i n polyethylene bags l o s t l e s s weight, maintained optimum c o l o r and g l o s s , and developed l e s s stem-end r o t than unwrapped f r u i t . 2

2

2



10.

BROWN

Fruit

Handling

and Decay

Control

213

T r a n s p o r t a t i o n . Deformation of c i t r u s f r u i t , due to i n adequate p r o t e c t i o n by the c o n t a i n e r , d e t r a c t s g r e a t l y from e x t e r n a l appearance. O v e r - f i l l i n g o f c a r t o n s , so t h a t weight o f stacked cartons i s supported by the f r u i t r a t h e r than the cont a i n e r , c o n t r i b u t e s s i g n i f i c a n t l y to deformation (294). Problems w i t h malformation occur more f r e q u e n t l y i n s i t u a t i o n s where f r u i t are transported over long d i s t a n c e s , such as during export. Hale (308) reported t h a t 33 to 60% of the F l o r i d a g r a p e f r u i t shipped to Japan a r r i v e d s e r i o u s l y deformed. Deformed g r a p e f r u i t were more p r e v a l e n t i n the bottom l a y e r of the carton regardless of the type of carton used. U s u a l l y , the l a r g e r the f r u i t , the more s e r i o u s l y the f r u i t were deformed. By packing f r u i t i n e x perimental (309) or i n t e r n a t i o n a l standard shipping cartons (310), which were somewhat deeper than the standard 4/5 bushel c a r t o n , deformity was reduced s i g n i f i c a n t l y s i n c e more of the weight was supported by the c a r t o n . C o n d i t i o n and appearance o f l a r g e s i z e d g r a p e f r u i t were improved by packing f r u i t i n s p e c i a l t r a y pack containers (311). Serious deformation o f tray-packed f r u i t was reduced to an average of 2.7%, compared to 27.9% f o r f r u i t shipped i n the standard export box. During handling and shipping g r a p e f r u i t from South A f r i c a to Europe, percentage j u i c e and r i n d thickness decreased (34). The percentage of t o t a l s o l u b l e s o l i d s increased and the a c i d content remained undamaged. Conclusions Q u a l i t y o f c i t r u s f r u i t s i s a l t e r e d q u i t e s i g n i f i c a n t l y by numerous techniques a p p l i e d before and a f t e r harvest. Since appearance of the f r u i t i s so v i t a l to consumer a c c e p t a b i l i t y , c o n s i d e r a b l e e f f o r t s towards improving and preserving the q u a l i t y of the r i n d can be expected i n f u t u r e s t u d i e s . Damage r e s u l t i n g from unnecessary rough handling during harvesting and processing predisposes f r u i t to increased decay caused by several wound pathogens. Even though e f f e c t i v e f u n g i c i d e s such as the b e n z i m i dazoles have been developed, these m a t e r i a l s can not be expected to cure the damage caused by improper handling. Rather, proper f u n g i c i d e a p p l i c a t i o n s combined w i t h good handling and s a n i t a r y techniques w i l l insure c i t r u s f r u i t s o f e x c e l l e n t keeping q u a l i t i e s . Problems w i t h fungal r e s i s t a n c e and lack of c o n t r o l of minor decays are s u f f i c i e n t to warrant f u r t h e r i n v e s t i g a t i o n s w i t h postharvest chemicals f o r decay c o n t r o l . Cold storage s t i l l appears to be the most e f f e c t i v e method f o r preserving q u a l i t y i n c i t r u s f r u i t s except f o r lemons and l i m e s . Recent s t u d i e s w i t h lemons have shown b e n e f i c i a l e f f e c t s of CA storage where ethylene i s e f f e c t i v e l y removed. S i m i l a r r e s u l t s have been obtained w i t h limes stored under low pressure (hypobaric) storage. Recent r e s u l t s i n improving keeping q u a l i t y o f c i t r u s f r u i t by i n d i v i d u a l l y wrapping them i n high d e n s i t y polyethylene await a d d i t i o n a l c o n f i r m a t i o n and a p p l i c a t i o n to commercial p r a c t i c e s .


214



Literature Cited 1. Ting, S. V.; Attaway, J. A. In "The Biochemistry of Fruits and Their Products", Hulme, A. C., Ed. Academic Press: London and New York, 1971; 2, p. 107-169. 2. Deszyck, E. J.; Ting, S. V. Proc. Am. Soc. Hortic. Sci., 1958, 72, 304. 3. Deszyck, E. J.; Ting, S. V. Proc. Am. Soc. Hortic. Sci., 1960, 75, 266. 4. Reese, R. L.; Brown, G. E. HortScience, 1964, 4, 96. 5. Anonymous. State of Florida Department of Citrus, Citrus Fruit Laws, Lakeland, FL 1974. 6. Coggins, C. W., Jr.; Hield, H. Z. In "The Citrus Industry"; Reuther, W.; Batchelor, L. D.; Webber, J. H., Eds.; Univ. Calif. Div. Agric. Sci.: Riverside, CA, 1968; 2, p. 373-389. 7. Warner, H. L.; Leopold, A. C. Plant Physiol., 1969, 44, 156. 8. El-Zeftawi, Β. M.; Garret, R. G. J. Hortic. Sci., 1978, 53, 215. 9. Jahn, O. L.; Young, R. J. Am. Soc. Hortic. Sci., 1972, 97, 544. 10. Young, R.; Jahn, O. J. Am. Soc. Hortic. Sci., 1972, 97, 237. 11. Young, R.; Jahn, O.; Cooper, W. C.; Smoot, J. J. HortScience, 1970, 5, 268. 12. Young, R.; Jahn, O.; Smoot, J. J. Proc. Fla. State Hortic. Soc., 1974, 87, 24. 13. Barmore, C. R.; Brown, G. E. Plant Dis. Rep., 1978, 62, 541. 14. Fishler, M.; Monselise, S. P. Israel J. Agric. Res., 1971, 21, 67. 15. Coggins, C. W., Jr. Acta Hortic., 1969, 34, 469. 16. Coggins, C. W., Jr. Proc. First Int. Citrus Symp., 1968, 3, 1177. 17. El-Zeftawi, Β. M.; Peggie, I. D. Food Technol. Aust., 1973, 25, 359. 18. Monselise, S. P. Acta Hortic., 1973, 34, 457. 19. Monselise, S. P. Proc. Int. Soc. Citriculture, 1977, 2, 664. 20. Monselise, S. P.; Sasson, A. Proc. Int. Soc. Citriculture, 1977, 1, 232. 21. Lewis, L. N.; Coggins, C. W., Jr.; Labananskas, C. K.; Dugger, W. M., Jr. Plant Cell Physiol., 1967, 8, 151. 22. Monselise, S. P.; Goren, R. Phyton, 1965, 22, 61. 23. Bevington, Κ. B. Aust. JL Exp. Agric. Anim. Husb., 1973, 13, 196. 24. Coggins, C. W., Jr.; Eaks, I. L. Calif. Citrogr., 1967, 52, 475. 25. Coggins, C. W., Jr.; Hield, H. Z.; Eaks, I. L.; Lewis, L. N.; Burns, R. M. Calif. Citrogr., 1965, 50, 457. 26. Coggins, C. W., Jr.; Jones, W. W. Proc. Int. Soc. Citri culture, 1977, 2, 686. 27. Coggins, C. W., Jr.; Scora, R. W.; Lewis, L. N.; Knapp, J. C. F. J. Agric. Food Chem., 1969, 17, 807.



10.

BROWN

Fruit

Handling

and

Decay

Control

215

28. El-Zeftawi, Β. M. J. Aust. Inst. Agric. Sci., 1971, 37, 151. 29. Erickson, L. C.; Richards, S. J. Proc. Am. Soc. Hortic. Sci. 1955, 65, 109. 30. Krezdorn, A. H.; Ali Dinar, H. M.; Rose, A. J. Proc. Fla. State Hortic. Soc., 1976, 89, 4. 31. Monselise, S. P. First World Congr. of Citriculture (Spain), 1973, 2, 393. 32. Stewart, W. S.; Hield, H. Z.; Brannaman, B. L. Hilgardia, 1952, 21, 301. 33. Gilfillan, I. M.; Koekemoer, W.; Stevenson, J. First World Congr. of Citriculture (Spain), 1973, 3, 355. 34. Gilfillan, I. M.; Stevenson, J. A. Citrus Subtrop. Fruit J., 1976, 507, 5. 35. Coggins, C. W., Jr.; Hield, H. Z.; Garber, M. J. Proc. Am. Soc. Hortic. Sci.., 1960, 76, 193. 36. Coggins, C. W., Jr.; Lewis, L. N. Plant Physiol., 1962, 37, 625. 37. Embleton, Τ. Α.; Jones, W. W.; Coggins, C. W., Jr. J. Am. Soc. Hortic. Sci., 1973, 98, 281. 38. Rodrigues, J.; Subramanyam, H. J. Sci. Food Agric., 1966, 17, 425. 39. Coggins, C. W., Jr.; Hield, H. Z.; Boswell, S. B. Proc. Am. Soc. Hortic. Sci., 1960, 76, 199. 40. Soost, R. K.; Burnett, P. H. Proc. Am. Soc. Hortic. Sci., 1961, 77, 194. 41. Coggins, C. W., Jr.; Eaks, I. L.; Hield, Η. Z.; Jones, W. W. Proc. Am. Soc. Hortic. Sci., 1963, 82, 154, 42. Eaks, I. L. Proc. First Int. Citrus Symp., 1968, 3, 1343. 43. Eaks, I. L.; Jones, W. W. Calif. Citrogr., 1959, 44, 390. 44. Coggins, C. W., Jr.; Lewis, L. N. Proc. Am. Soc. Hortic. Sci., 1965, 86, 272. 45. Riehl, L. Α.; Coggins, C. W., Jr.; Carman, G. E. Calif. Citrogr., 1965, 51, 2. 46. Riehl, L. Α.; Coggins, C. W., Jr.; Carman, G. E. J. Econ. Entomol., 1966, 59, 615. 47. Erner, Y.; Goren, R.; Monselise, S. P. J. Am. Soc. Hortic. Sci., 1976, 101, 513. 48. Leggo, D. Agric Gaz. N.S.W., 1968, 79, 112. 49. Monselise, S. P.; Weiser, M.; Shafir, N.; Goren, R.; Goldschmidt, Ε. E. J. Hortic. Sci., 1976, 51, 341. 50. Ismail, Μ. Α.; Grierson, W. HortScience, 1977, 12, 118. 51. Albrigo, L. G.; Brown, G. E.; Fellers, P. J. Proc. Fla. State Hortic. Soc., 1970, 83, 263. 52. Albrigo, L. G.; Brown, G. E. First World Congr. Citriculture (Spain), 1973, 3, 361. 53. Hopkins, E. F.; Loucks, K. W. Proc. Fla. State Hortic. Soc., 1944, 57, 80. 54. Pelser, P. Du T. S. Afr. Citrus Subtrop. Fruit J., 1973, 475, 5. 55. PFTseri P. Du T. S. Afr. Citrus Subtrop. Fruit J., 1977,519, 5.



216


56. Sites, J. W.; Reitz, H. J. Proc. Am. Soc. Hortic. Sci., 1949, 54, 1. 57. Sites, J. W.; Reitz, H. J. Proc. Am. Soc. Hortic. Sci., 1950, 55, 73. 58. Sites, J. W.; Reitz, H. J. Proc. Am. Soc. Hortic. Sci., 1951, 56, 103. 59. Christ, R. A. S. Afr. Citrus J., 1966, 387, 7. 60. McCornack, A. A. Proc. Fla. State Hortic. Soc., 1973, 86, 284. 61. Smoot, J. J.; Melvin, C. F. Proc. Fla. State Hortic. Soc., 1961, 74, 285. 62. Smoot, J. J.; Melvin, C. F. Proc. Fla. State Hortic. Soc., 1975, 88, 276. 63. McCornack, A. A. Proc. Fla. State Hortic. Soc., 1966, 79, 258. 64. Rivero, L. G.; Grierson, W.; Soule, J. J. Am. Soc. Hortic. Sci., 1979, 104, 551. 65. Fawcett, H. S. Calif. Agric. Exp. Stn. Bull. 266, 1916, 259. 66. Cahoon, G. Α.; Grove, B. L.; Eaks, I. L. Proc. Am. Soc. Hortic. Sci., 1964, 84, 188. 67. Eaks, I. L. Proc. Am. Soc. Hortic. Sci., 1955, 66, 141. 68. McCornack, A. A. Proc. Fla. State Hortic. Soc., 1970, 83, 267. 69. Miller, Ε. V.; Winston, J. R. Citrus Ind., 1943, 24, 7. 70. Wardowski, W. F.; McCornack, Α. Α.; Grierson, W. Fla. Coop. Ext. Serv. Circ. 410, 1976, p. 6. 71. Levy, Y.; Greenberg, J . ; Ben-Anat, S. Sci. Hortic., 1979, 11, 61. 72. Grierson, W.; Brown, G. E. Citrus Ind., 1966, 47, 8. 73. Grierson, W.; Koo, R. C. J. Citrus Veg. Mag., 1958, 21, 8. 74. Hopkins, E. F.; McCornack, A. A. Proc. Fla. State Hortic. Soc., 1960, 73, 263. 75. McCornack, A. A. Proc. Fla. State Hortic. Soc., 1972, 85, 232. 76. McCornack, Α. Α.; Grierson, W. Fla. Coop. Ext. Serv. Circ. 286, 1965, 3 p. 77. Albrigo, L. G. J. Am. Soc. Hortic. Sci., 1972, 97, 220. 78. Grierson, W.; Pantastico, Ε. B. Proc. Trop. Reg., Am. Soc. Hortic. Sci., 1968, 11, 1. 79. Hatton, T. T., Hr.; Reeder, W. F. Citrus Ind., 1967, 48, 23. 80. Hatton, T. T., Jr.; Reeder, W. F. Proc. Fla. State Hortic. Soc., 1968, 81, 344. 81. Pantastico, Ε. B.; Grierson, W.; Soule, J. Proc. Fla. State Hortic. Soc., 1966, 79, 388. 82. Cunha, G. A.; Davenport, T. L.; Soule, J.; Campbell, C. W. J. Am. Soc. Hortic. Sci., 1978, 103, 622. 83. Davenport, T. L.; Campbell, C. W. HortScience, 1977,12,246. 84. Davenport, T. L.; Campbell, C. W. J. Am. Soc. Hortic. Sci., 1977, 102, 484.



10.

BROWN

Fruit

Handling

and

Decay

Control

211

85. Davenport, T, L.; Campbell, C. W.; Orth, P. G. Proc. Fla. State Hortic. Soc., 1976, 89, 245. 86. Eaks, I. L. Proc. Am. Soc. Hortic Sci., 1964, 85, 245. 87. Brown, G. K.; Schertz, C. E. Trans. ASAE., 1967, 10, 577. 88. El-Zeftawi, Β. M.; Thornton, I. R.; Gould, I. V. HortScience, 1977, 52, 461. 89. Grierson, W. Proc. Fla. State Hortic. Soc., 1968, 81, 53. 90. Chesson, J. H. Trans. ASAE., 1972, 15, 31. 91. Rackham, R. L.; Grierson, W. HortScience, 1971, 6, 163. 92. Ben-Yehoshua, Α.; Sarig, Y.; Golcomb, A. First World Congr. Citriculture (Spain), 1973, 3, 647. 93. Bryan, W. L. Trans. Citrus. Eng. Conf. ASME, 1974, 20, 24. 94. Bryan, W. L. Proc. Int. Soc. Citriculture, 1977, 3, 763. 95. Coppock, G. E.; Grierson, W. Citrus Ind., 1970, 51, 6. 96. Wilson, W. C.; Holm, R. E.; Clark, R. K. Proc. Int. Soc. Citriculture, 1977, 2, 404. 97. Moshonas, M. G.; Shaw, P. E.; Sims, D. A. J. Food Sci., 1976, 41, 809. 98. Moshonas, M. G.; Shaw, P. E.; Sims, D. A. Proc. Int. Soc. Citriculture, 1977, 3, 802. 99. Moshonas, M. G.; Shaw, P. E. J. Agric. Food Chem., 1977, 25, 1151. 100. Grierson, W. Proc. Fla. State Hortic. Soc., 1958, 71, 166. 101. Eaks, I. L. Proc. Int. Soc. Citriculture, 1977, 1, 223. 102. Moshonas, M. G.; Shaw, P. E. Int. Flav. Food AddTt., 1977, July-Aug., 149. 103. Grierson, W.; Newhall, W. F. Proc. Am. Soc. Hortic. Sci., 1956, 67, 236. 104. Gaffney, J. J.; Jahn, O. L Proc. Fla. State Hortic. Soc., 1967, 80, 296. 105. Jahn, O. L.; Yost, G. E.; Soule, J. U.S. Dep. Agric., Agric. Res. Ser. Rep. 51-14, 1967, p. 14. 106. Cohen, E. Spec. Pub. 128, Div. Scientific Pub. Volcanic Ctr.: Bet Dagan, Israel, 1979; p. 72. 107. Gillespie, K.; Tugwell, B. L. Dep. Agric. S. Aust. Spec. Bull. No. 4.75, 1975, p.7. 108. Grierson, W.; Newhall, W. F. Fla. Agric. Exp. Stn. Bull. 620, 1960, p. 80. 109. Hall, E. G.; Leggo, D.; Seberry, J. A. Agric. Gaz. J. N.S.W., 1968, 79, 721. 110. Jahn, O. L. First World Congr. of Citriculture (Spain), 1973 3 291 111. Jorgensen, K. R. Queensl. Agric. J., 1977, 103, 85. 112. Wardowski, W. F.; McCornack, A. A. Fla. Coop. Ext. Serv. Circ. 389, 1973, p. 3. 113. Winston, J. R. U.S. Dep. Agric. Circ. 961, 1955, p. 13. 114. Cohen, E. J. Hortic. Sci., 1978, 53, 143. 115. Grierson, W.; Newhall, W. F. Proc. Fla. State Hortic. Soc., 1953, 66, 42.



218


116. Jahn, O. L.; Chace, W. G., Jr.; Cubbedge, R. H. J. Am. Soc. Hortic. Sci., 1973, 98, 177. 117. Kitagawa, H.; Kawada, K.; Tarutani, T. Proc. Int. Soc. Citriculture, 1977, 1, 219. 118. Kitagawa, H.; Kawada, K.; Tarutani, T. J. Am. Soc. Hortic. Sci., 1978, 103, 113. 119. Cohen, E. Proc. Int. Soc. Citriculture, 1977, 1, 215. 120. Cohen, E. First Int. Congr. Citriculture (Spain), 1973, 3, 297. 121. Jahn, O. L.; Chace, W. G., Jr.; Cubbedge, R. H. J. Am. Soc. Hortic. Sci., 1969, 94, 123. 122. Zamorani, Α.; Russo, C.; Monaco, M. First World Congr. of Citriculture (Spain), 1973, 3, 303. 123. Grierson, W. Proc. Trop. Reg., Am. Soc. Hortic. Sci., 1974, 18, 66. 124. Fulton, H. R.; Stevens, H. E.; Wooten, J. F. Proc. Fla. State Hortic. Soc., 1929, 42, 181. 125. Grierson, W.; Newhall, W. F. Proc. Am. Soc. Hortic. Sci., 1955, 65, 244. 126. Grierson, W.; Ting, S. V. Proc. Fla. State Hortic. Soc., 1960, 73, 284. 127. Loucks, K. W.; Hopkins, E. F. Phytopathol., 1946, 36, 750. 128. Cohen, E. J. Hortic. Sci., 1978, 53, 139. 129. McCornack, A. A. Proc. Fla. State Hortic. Soc., 1971, 84, 270. 130. Smoot, J. J.; Melvin, C. F. Proc. Fla. State Hortic. Soc., 1967, 80, 246. 131. Smoot, J. J.; Melvin, C. F.; Jahn, O. L. Plant Dis. Rep., 1971, 55, 149. 132. Brown, G. E. Phytopathol., 1975, 65, 404. 133. Brown, G. E.; Barmore, C. R. Phytopathol., 1977, 67, 120. 134. Brown, G. E. Phytopathol., 1978, 68, 700. 135. Hopkins, E. F.; Loucks, K. W. Fla. Agric. Exp. Stn. Bull. 450, 1948, p. 26. 136. Brown, G. E. Phytopathol., 1973, 63, 1104. 137. Jahn, O. L. J. Am. Soc. Hortic. Sci., 1975, 100, 586. 138. Smoot, J. J.; Melvin, C. F. Proc. Fla. State Hortic. Soc., 1972, 85, 235. 139. Hatton, T. T., Jr.; Cubbedge, R. H. HortScience, 1973, 8, 101. 140. Albrigo, L. G. First World Congr. of Citriculture (Spain), 1973, 3, 107. 141. Stewart, I.; Wheaton, T. A. Proc. Fla. State Hortic. Soc., 1971, 84, 264. 142. Stewart, I.; Wheaton, T. A. J. Agric. Food Chem., 1972, 20, 448. 143. Wheaton, Τ. Α.; Stewart, I. J. Am. Soc. Hortic. Sci., 1973, 98, 337 144. Young, R.; Jahn, O. J. Am. Soc. Hortic. Sci., 1972, 97, 258.



10.

BROWN

Fruit Handling

and

Decay

Control

219

145. Fuchs, Y.; Cohen, A. J. Am. Soc. Hortic. Sci., 1969, 94, 617. 146. Grierson, W.; Ismail, F. H.; Oberbacher, M. F. J. Am. Soc. Hortic. Sci., 1972, 97, 541. 147. Jahn, O. L. Am. Soc. Hortic. Sci., 1973, 98, 230. 148. Jahn, O. L. Proc. Fla. State Hortic. Soc., 1974, 87, 218. 149. Jahn, O. L. J. Am. Soc. Hortic. Sci., 1976, 101, 597. 150. Wardowski, W. F.; Barmore, C. R.; Smith, T. S.; Dubois, C.W. Proc. Fla. State Hortic. Soc., 1974, 87, 216. 151. Gertman, E.; Fuchs, Y. HortScience, 1975, 10, 231. 152. Gertman, E.; Fuchs, Y. Israel J. Agric. Res., 1973, 23, 25. 153. Oberbacher, M. F.; Grierson, W. Proc. Fla. State Hortic. Soc., 1960, 73, 236. 154. Barmore, C. R.; Wheaton, Τ. Α.; McCornack, A. A. Hort Science, 1976, 11, 588. 155. Barmore, C. R.; Wheaton, Τ. Α.; McCornack, A. A. Citrus Ind., 1976, 57, 38. 156. Hayman, E. P.; Yokoyama, H.; Poling, S. M. J. Agric. Food Chem., 1977, 25, 1251. 157. Jahn, O. L.; Young, R. J. Am. Soc. Hortic. Sci., 1975, 100, 244. 158. Valadon, L. R. G.; Mummery, R. S. Phytochemistry, 1978, 17, 818. 159. Yokoyama, H.; Debenedict, C.; Coggins, C. W., Jr.; Henning, G. L. Phytochemistry, 1972, 11, 1721. 160. Coggins, C. W., Jr.; Hall, A. E. J. Am. Soc. Hortic. Sci., 1975, 100, 484. 161. Grierson, W.; Wardowski, W. F. In "Citrus Science and Technology"; Nagy, S.; Shaw, P. E.; Veldhuis, M. K. Eds.; Avi Publishing Co., Inc.: Westport, CT, 1977; 2, p.128-140. 162. Eckert, J. W. In "Fungicides: An Advanced Treatise"; Torgeson, D. C., Ed.; Academic Press: New York and London, 1967; 1, p. 287-378. 163. Eckert, J. W. World Rev. Pest Control, 1969, 8, 116. 164. Eckert, J. W. In "Antifungal Compounds"; Siegel, M. R.; Sisler, H. D., Eds.; Marcel Dekker, Inc.: New York, NY, 1977; 1, p. 269-352. 165. Eckert, J. W.; Sommer, N. F. Ann. Rev. Phytopathol., 1967, 5, 391. 166. Eckert, J. W. Outlook Agric., 1978, 9, 225. 167. Eckert, J. S.; Kolbezen, M. J. Proc. 6th British Insec ticide and Fungicide Conf., 1971, 3 683. 168. McCornack, Α. Α.; Wardowski, W. F.; Brown, G. E. Fla. Coop. Ext. Serv. Circ. 359A, 1976, 6 p. 169. Cresswell, G. A. S. Afr. Citrus J . , 1964, 361, 19. 170. Eckert, J. W.; Kolbezen, M. J.; Krainer, B. A. Proc. First Int. Citrus Symp., 1968, 2, 1097. 171. Hopkins, E. F.; Loucks, K. W. Science, 1950, 112, 720. 172. Razzman, Α.; Apelbaum, Α.; Heller, H. Pest. Sci., 1972, 3, 585. 9



220


173. Brown, G. E. Proc. Int. Soc. Citriculture, 1977, 1, 283. 174. Eckert, J. W.; Kolbezen, M. J. Neth. J. Plant Pathol., Suppl., 1, 1977, 83, 343. 175. Eckert, J. W.; Kolbezen, M. J . ; Rahm, M. L.; Eckard, K. J. Phytopathol., 1979, 69, 934. 176. Eckert, J. W.; Kolbezen, M. J. First World Congr. of Citri culture (Spain), 1973, 3 559. 177. DeWolfe, T. Α.; Erickson, L. C.; Brannaman, B. L. Proc. Am. Soc. Hortic. Sci., 1968, 74, 367. 178. Schiffmann-Nadel, M. Proc. First Int. Citrus Symp., 1968, 3, 1295. 179. Schiffmann-Nadel, M.; Lattar, F. S.; Waks, J. HortScience, 1972, 7, 120. 180. Stewart, W. S. Proc. Am. Soc. Hortic. Sci., 1949, 54, 109. 181. Stewart, W. S.; Palmer, J. E.; Hield, Η. Z. Proc. Am. Soc. Hortic. Sci., 1952, 59, 327. 182. Weyer, F. P. S. Afr. Citrus J., 1969, 422, 13. 183. El-Nabawy, S.; El-Hammady, M. M.; El-Hammady, A. M.; ElGazyawy, A. Proc. Int. Soc. Citriculture, 1977, 3, 1135. 184. Fahmy, Β. Α.; Rizk, S. S.; Khalil, R. I. Agric. Res. Rev., 1972, 50, 83. 185. Blunden, G.; Jones, E. M.; Passam, H. C.; Metcalf, E. Trop. Agric., 1979, 56, 311. 186. Harding, P. R., Jr.; Savage, D. C. Plant Dis. Rep., 1964, 48, 808. 187. Melvin, C. F.; Smoot, J. J. Proc. Fla. State Hortic. Soc., 1963, 76, 322. 188. Smoot, J. J . ; Melvin, C. F. Plant Dis. Rep., 1965, 49, 463. 189. Klotz, L. J . ; De Wolfe, T. A. Plant Dis. Rep., 1961, 45, 264. 190. Barkai-Golan, R.; Kahan, R. S. Plant Dis. Rep., 1966, 50, 874. 191. Guerrero, F. P.; Maxie, E. C.; Johnson, C. F.; Eaks, I. L.; Sommer, N. F. Proc. Am. Soc. Hortic. Sci., 1967, 90, 515. 192. Grierson, W.; Dennison, R. A. Proc. Fla. State Hortic, Soc., 1965, 78, 233. 193. Mahmood, T. Plant Dis. Rep., 1972, 56, 582. 194. Maxie, E. C.; Sommer, N. F.; Eaks, I. L. First Int. Citrus Symp., 1968, 3, 1375. 195. Maxie, E. C.; Eaks, I. L.; Sommer, N. F. Rad. Bot., 1964, 4, 405. 196. Maxie, E. C.; Eaks, I. L.; Sommer, N. F.; Rae, H. L.; El-Batel, S. Plant Physiol., 1965, 40, 407. 197. Ben-Yehoshua, S. Israel J. Agric. Res., 1967, 17, 17. 198. Ben-Yehoshua, S.; Garber, M. J . ; Huszar, C. K. Trop. Agric., 1970, 47, 151. 199. Oavis, P. L.; Chace, W. G., Jr.; Cubbedge, R. H. Hort Science, 1967, 2, 168. 200. Eaks, I. L.; Ludi, W, A. Proc Am. Soc. Hortic. Sci., 1960, 76, 220.



10.

BROWN

Fruit

Handling

and

Decay Control

221

201. Vines, H. M.; Grierson, W.; Edwards, G. J. Proc. Am. Soc. Hortic. Sci., 1968, 92, 227. 202. Davis, P. L. Proc. Fla. State Hortic. Soc., 1970, 83, 294. 203. Davis, P. L.; Hofmann, R. C. J. Agric. Food Chem., 1973, 21, 455. 204. Long, W. G. Fla. Agric. Exp. Stn. Bull. 681, 1964, p. 38. 205. Davis, P. L.; Harding, P. L. J. Am. Soc. Hortic. Sci., 1960, 75, 271. 206. Grierson, W. Proc. Trop. Reg., Am. Soc. Hortic. Sci., 1971, 15, 76. 207. Chace, W. G., Jr.; Davis, P. L.; Smoot, J. J. XII Int. Cong. Refrig. (Madrid), 1967, 3, 383. 208. Seberry, J. Α.; Leggo, D.; Keily, T. B. Aust. J. Exp. Agric. Anim. Husb., 1967, 7, 593. 209. Hatton, T. T., Jr.; Reeder, W. F. Proc. Trop. Reg., Am. Soc. Hortic. Sci., 1968, 11, 23. 210. Aharoni, Y.; (Littauer) Lattar, F. S.; Angel, S. Hort Science, 1973, 8, 58. 211. Alumot, E.; Chalutz, E. Pest Sci., 1972, 3, 539. 212. Chalutz, E.; Schiffmann-Nadel, M.; Waks, J . ; Alumot, E.; Carmi, Y.; Bussel, J. J. Am. Soc. Hortic. Sci. 1971, 96, 782. 213. Grierson, W.; Hayward, F. W. Proc. Fla. State Hortic. Soc., 1959, 73, 267. 214. Grierson, W.; Miller, W. M.; Wardowski, W. F.; Ismail, M. A. Proc. Fla. State Hortic. Soc., 1976, 89, 172. 215. Leggo, D.; Gellatley, J. G.; Seberry, J. Α.; Peggie, I. D.; Long, J. K.; Hall, E. G. Agric. Gaz. N.S.W., 1965, 76, 274. 216. Lindgren, D. L.; Sinclair, W. B. J. Econ. Entomol., 1951, 44, 980. 217. Norman, G. Α.; Grierson, W.; Wheaton, Τ. Α.; Dennis, J. D. Proc. Fla. State Hortic. Soc., 1975, 88, 323. 218. Swaine, G., Corcoran, R. J.; Cranny, A. E.; Davey, M. A. Pest Sci., 1978, 9, 22. 219. Sinclair, W. B.; Lindgreen, D. L.; Forbes, R. J. Econ. Entomol., 1962, 55, 236. 220. Bussel, J . ; Kamburov, S. S. J. Am. Soc. Hortic. Sci., 1976, 101, 11. 221. Eaks, I. L.; Ludi, W. A. Proc. Am. Soc. Hortic. Sci., 1958, 72, 297. 222. Chalutz, E.; Biron, S.; Alumot, E. Int. Inst. Refrig. Commission C2, (Jersualem) 1973, 205. 223. Winston, J. R.; Roberts, C. L. Proc. Fla. State Hortic. Soc., 1944, 57, 140. 224. Iwamato, M.; Hayakawa, Α.; Kawano, S.; Manago, M. J. Soc. Agric. Mach (Japan), 1977, 38, 539. 225. Eaks, I. L. Proc. Am. Soc. Hortic. Sci., 1960, 78, 190. 226. Yamashita, Y.; Kitano, Y.; Hatta, S.; Wada, T.; Uda, H. J. Jpn. Soc. Hortic. Sci., 1979, 48, 231.



222


227. Yamashita, S.; Wada, T.; Kitano, Y.; Hatta, S.; Uda. H. J. Jpn. Soc. Hortic. Sci., 1979, 48, 242. 228. Bruemmer, J. H. Proc. Fla. State Hortic. Soc., 1970, 83, 290. 229. Bruemmer, J. H.; Roe, B. Proc. Fla. State Hortic. Soc., 1969, 82, 212. 230. Maier, V. P.; Brewster, L. C.; Hsu, A. C. J. Agric. Food Chem., 1973, 21, 490. 231. Bartholomew, E. T.; Sinclair, W. B. "The Lemon Fruit". Its Composition, Physiology and Products"; Univ. Calif. Press: Berkeley, CA, 1951; p. 163. 232. Biale, J. B. In "The Orange, Its Biochemistry and Physi ology"; Sinclair, W. B. Ed; Univ. of Calif., Div. Agric. Sci.: Riverside, CA, 1961; p. 96-113. 233. Kefford, J. F.; Chandler, Β. V. "The Chemical Constituents of Citrus Fruits"; Advances in Food Research Suppl. 2; Academic Press: New York and London, 1970; p. 246. 234. Miller, Ε. V. Bot. Rev., 1946, 12, 393. 235. Miller, Ε. V. Bot. Rev., 1958, 24, 43. 236. Rose, D. H.; Cook, H. T.; Redit, W. H. USDA Bibliogr. Bull. No. 13, 1951, p. 178. 237. Sinclair, W. B. In "The Grapefruit, its Composition, Physi ology, and Products"; Sinclair, W. B., Ed.; Univ. of Calif., Div. of Agric. Sci.: Riverside, CA, 1972; p. 426-501. 238. Eaks, I. L. J. Food Sci., 1961, 26, 593. 239. Bratley, C. O. Proc.Am.Soc. Hortic. Sci., 1939, 37, 526. 240. El-Zeftawi, B. M. J. Hortic. Sci., 1976, 51, 411. 241. Isshak, Y. M.; Rizk, S. S.; Khalil, R. I.; Fahmi, B. A. Agric. Res. Rev. Mar., 1974, 52, 80. 242. Sasson, Α.; Monselise, S. P. J. Am. Soc. Hortic. Sci., 1977, 102, 331. 243. Davis, P. L.; Hofmann, R. C.; Hatton, T. T., Jr. HortScience, 1974, 9, 376. 244. Davis, P. L. Proc. Fla. State Hortic. Soc., 1971, 84, 217. 245. Caro, J.; Prestamo, G.; Calvo, J. M. Proc. Int. Soc. Citri culture, 1977, 3, 1120. 246. Pantastico, Ε. B.; Soule, J.; Grierson, W. Proc. Trop. Reg., Am. Soc. Hortic. Sci., 1968, 12, 171. 247. Hatton, T. T., Jr.; Cubbedge, R. H.; Grierson, W. Proc. Fla, State Hortic. Soc., 1975, 88, 335. 248. Hawkins, L. A. J. Agric. Res., 1921, 22, 263. 249. Hawkins, L. Α.; Barger, W. R. U.S. Dep. Agric. Tech. Bull. 1368, 1926, p. 7. 250. Chace, W. G., Jr.; Harding, P. L.; Smoot, J. J . ; Cubbedge, R. H. U.S. Dep. Agric. Mark. Res. Rep. 739, 1966, p. 21. 251. Schiffmann-Nadel, M.; Chalutz, E.; Waks, J . ; Dagan, M. J. Am. Soc. Hortic. Sci., 1975, 100, 270. 252. Brooks, C.; McColloch, L. P. J. Agric. Res., 1936, 52, 319. 253. Davis, P. L.; Hofmann, R. C. J. Food Sci., 1973, 38, 871.


10.

BROWN

Fruit

Handling

and

Decay

Control

254. Brooks, C.; Bratley, C. O.; McColloch, L. P. U.S. Dep. Agric. Tech. Bull. No. 519, 1936, p. 24. 255. Brooks, C.; McColloch, L. P. J. Agric. Res., 1937, 55, 795. 256. Hatton, T. T., Jr.; Smoot, J. J . ; Cubbedge, R. H. Proc. Trop. Reg., Am. Soc. Hortic. Sci., 1972, 16, 49. 257. Vakis, N.; Grierson, W.; Soule, J. Proc. Trop. Reg., Am. Soc. Hortic. Sci., 1970, 14, 89. 258. Wardowski, W. F.; Albrigo, L. G.; Grierson, W.; Barmore, C. R.; Wheaton, T. A. HortScience, 1975, 10, 381. 259. Kokkalos, T. I. HortScience, 1974, 9, 456. 260. Schiffmann-Nadel, M.; Chalutz, E.; Waks, J . ; Lattar, F. S. HortScience, 1972, 7 394. 261. McCornack, A. A. Proc. Fla. State Hortic. Soc.,1976,89,200. 262. Chalutz, E.; Schiffmann-Nadel, M.; Waks, J.; Lattar, F. S. J. Am. Soc. Hortic. Sci., 1974, 99, 368. 263. Grierson, W.;HaywardF. W. Proc. Am. Soc. Hortic. Sci., 1960, 76, 229. 264. Hayward, F. W. Proc. Fla. State Hortic. Soc., 1962, 75, 302. 265. Eaks, I. L. Calif. Citrogr., 1955, 41, 68. 266. Grierson, W.; Hayward, F. W. Proc. Fla. State Hortic. Soc., 1958, 71, 205. 267. Chace, W. G., Jr. Proc. First Int. Citrus Symp., 1968, 3, 1365. 268. Chace, W. G., Jr.; Smoot, J. J.; Cubbedge, R. H. Citrus Ind., 1970, 51, 16. 269. Seberry, J. A.; Hall, E. G. Agric. Gaz. N.S.W., 1970, 81, 564. 270. Aharoni, Y.; Lattar, F. S. Phytopathol. Z., 1972, 73, 371. 271. Harding, P. R., Jr. Plant Dis. Rep., 1969, 53, 585. 272. Salama, S. B.; Grierson, W.; Oberbacher, M. F. Proc. Fla. State Hortic. Soc., 1965, 78, 353. 273. Carreres, R.; Tuset, J. J . ; Lloret, J. L. Proc. Int. Soc. Citriculture, 1977, 3, 1133. 274. Davis, P. L.; Roe, B.; Bruemmer, J. H. J. Food Sci., 1973, 38, 225. 275. Smoot, J. J. Proc. First Int. Citrus Symp., 1968, 3, 1285. 276. Oogaki, C.; Manago, M. Proc. Int. Soc. Citriculture, 1977, 3, 1127. 277. Houck, L. G.; Aharoni, Y.; Fouse, D. C. Proc. Fla. State Hortic. Soc., 1978, 91, 136. 278. Biale, J. B. Calif. Citrog., 1953, 38, 427. 279. Grierson, W.; Vines, H. M.; Oberbacher, M. F.; Ting, S. V.; Edwards, G. J. Proc. Am. Soc. Hortic. Sci., 1966, 88, 311. 280. McGlasson, W. B.; Eaks, I. L. HortScience, 1972, 7, 80. 281. Schiffmann-Nadel, M. Proc. Int. Soc. Citriculture, 1977, 1, 311. 282. Hall, E. G.; Scott, K. J.; Wild, B. L.; Rippon, L. E. First 9


223

World Congr. of Citriculture (Spain) 1973, 3, 347.



224


283. Wild, B. L.; McGlasson, W. B.; Lee, T. H. HortScience, 1976, 11, 114. 284. Wild, B. L.; McGlasson, W. B.; Lee, T. H. Proc. Int. Soc. Citriculture, 1977, 1, 259. 285. Wild, B. L.; McGlasson, W. B.; Lee, T. H. Food Technol. Aust., 1977, 29, 351. 286. Spalding, D. H.; Reeder, W. F. Proc. Trop. Reg., Am. Soc. Hortic. Sci., 1974, 18, 128. 287. Burg, S. P.; Burg, E. A. Science, 1966, 153, 314. 288. Spalding, D. H.; Reeder, W. F. J. Am. Soc. Hortic. Sci., 1976, 101, 367. 289. Apelbaum, Α.; Barkai-Golan, R. Phytopathol., 1977, 67, 400. 290. Grierson, W. Proc. Fla. State Hortic. Soc., 1966, 79, 274. 291. Grierson, W. Proc. First Int. Citrus Symp., 1968, 3, 1389. 292. Grierson, W. Int. Inst. Refrig., Commission C2 (Jerusalem), 1973, 51. 293. Risse, L. Α.; Hatton, T. T., Jr. Citrus Ind., 1975, 56, 19. 294. Smith, R. J. Proc. First Int. Citrus Symp., 1968, 2, 689. 295. Grierson, W.; Wardowski, W. F. HortScience, 1978, 13, 570. 296. Hardenburg, R. E. HortScience, 1971, 6, 198. 297. Harding, P. R., Jr. Plant Dis. Rep., 1959, 43, 893. 298. Hayward, F. W.; Grierson, W.; Edwards, G. J. Proc. Fla. State Hortic. Soc., 1965, 78, 244. 299. Hayward, F. W.; Oberbacher, M. F.; Grierson, W. Proc. Fla. State Hortic. Soc., 1961, 74, 237. 300. Kaufman, J . ; Hardenburg, R. E.; Lutz, J. M. Proc. Am. Soc. Hortic. Sci., 1956, 67, 244. 301. Vines, H. M.; Oberbacher, M. F. Proc. Fla. State Hortic. Soc., 1961, 74, 243. 302. Rygg, G. L. Citrus Leaves, 1951, 32, 12. 303. Stahl, A. L.; Fifield, W. M. Fla. Agric Exp. Stn. Bull. 304, 1936, p. 78. 304. Wardowski, W. F.; Grierson, W.; Edwards, G. J. HortScience, 1973, 8, 173. 305. Ben-Yehoshua, S. Proc. Int. Soc. Citriculture, 1978, (In Press). 306. Ben-Yehoshua, S.; Kobiler, I.; Shapiro, B. J. Am. Soc. Hortic. Sci., 1979, 104, 868. 307. Kawada, K.; Albrigo, L. G. Proc. Fla. State Hortic. Soc., 1979, 92, (In Press). 308. Hale, P. W.; Smoot, J. J. Citrus Veg. Mag., 1973, 37, 20. 309. Smoot, J. J . ; Hale, P. W. Proc. Fla. State Hortic. Soc., 1977, 90, 152. 310. Hale, P. W.; Smoot, J. J . ; Miller, W. R. Proc. Fla. State Hortic. Soc., 1978, 91, 133. 311. Hale, P. W. Citrus Veg. Mag., 1976, 40, 12. RECEIVED May 13,

1980.


Citrus Nutrition and Quality - American Chemical Society

Recommend Documents