Quality of Selected Fruits and Vegetables of North America - American

4 Raisin and Dried Fig Volatile Components: Possible Insect Attractants RON G. BUTTERY, RICHARD M. SEIFERT and LOUISA C. LING Western Regional Research Laboratory, SEA, USDA, Berkeley CA 94710

Downloaded by FUDAN UNIV on December 23, 2016 | http://pubs.acs.org Publication Date: November 11, 1981 | doi: 10.1021/bk-1981-0170.ch004

EDWIN I. SODERSTROM and ALBERT P. YERINGTON StoredProductsInsectsResearchLaboratory,SEA,USDA,Fresno,CA93727

The vacuum steam volatile oils of both raisins and dried figs have been analyzed by capillary GLC-mass spectrometry. A total of 38 components were identified in the volatile oil of raisins and 34 components in the volatile oil of dried figs. Major volatile components in both raisins and dried figs included fatty acid degradation products such as nonanoic and octanoic acids, (E)-2decenal, (E)-2-octenal and nonanal. Benzaldehyde was an additional major component of dried figs. The most unusual components were 2-hexyl-3-methyl-maleic anhydride and l-octen-3one in the raisin volatile oil. Certain insects such as the Indian meal moth (Plodia interpunctella) and saw tooth grain beetle (Oryzaephilus surinamensis) infest dried fruits. It seems reasonable that these insects are attracted to the dried fruit, at least to some extent, by the characteristic odor of the dried fruit. The present study was begun to identify the volatile (odor) components of raisins and dried figs in order to be in a position to test these compounds for attraction. The volatiles of raisins had been previously studied by Ramshaw and Hardy (1). The volatiles of fresh figs had been previously studied by Jennings (2). EXPERIMENTAL Materials. Good quality dried raisins (dried Thompson seedless grapes), dried figs and fresh figs (Calimyrna variety) were obtained from processors in the Fresno, California area and from local markets for comparison. Authentic chemical compounds for comparison were obtained from reliable commercial sources or synthesized by known methods. Isolation of Volatile Oils. Whole raisins (1500g) were placed in a 12 L flask together with 6 L of odor free water. A Likens-Nickerson steam d i s t i l l a tion continuous extraction head was attached to the flask. This chapter not subject to U.S. copyright. Published 1981 American Chemical Society Teranishi and Barrera-Benitez; Quality of Selected Fruits and Vegetables of North America ACS Symposium Series; American Chemical Society: Washington, DC, 1981.


30

QUALITY OF

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VEGETABLES

P u r i f i e d hexane (100 mL) was p l a c e d i n a 250 mL f l a s k a t t a c h e d t o the s o l v e n t arm of the head. The i s o l a t i o n was c a r r i e d out under reduced pressure (100 mm Hg) f o r 3 hours w i t h the r a i s i n s a t ca. 50°C. Cooling of the head condenser was c a r r i e d out w i t h an ethanol-water mixture a t 0°C. A dry i c e cooled r e f l u x condenser was placed on the o u t l e t of the head. A f t e r the i s o l a t i o n the hexane e x t r a c t was d r i e d by f r e e z i n g out any drops of water and f i l t e r e d . The hexane s o l u t i o n was then concentrated u s i n g low hold up d i s t i l l a t i o n columns t o g i v e the r a i s i n volatile oil. The v o l a t i l e o i l from whole d r i e d f i g s was i s o l a t e d u s i n g e s s e n t i a l l y the same procedure as f o r the r a i s i n s except that the weight of d r i e d f i g s was 1 Kg. The v o l a t i l e o i l from whole f r e s h f i g s was i s o l a t e d a l s o u s i n g e s s e n t i a l l y the same procedure as f o r r a i s i n s except u s i n g 3 Kg of f r e s h f i g s . V o l a t i l e O i l from Fermented

Figs.

D r i e d f i g s (1 Kg) were added t o water (1.5 L) i n a 5 L beaker. Bakers yeast (0.25 g) was then added and the mixture s t i r r e d b r i e f l y . The beaker was covered w i t h c h e e s e c l o t h and the mixture allowed t o ferment a t room temperature (25°C) f o r 3 days. The mixture together w i t h 4 L of odor f r e e water was t r e a t e d u s i n g a Likens-Nickerson head vacuum steam d i s t i l l a t i o n c o n t i n u a l e x t r a c t i o n procedure as d e s c r i b e d above f o r r a i s i n s . Other batches of fermented f i g prepared as above were e x t r a c t e d d i r e c t l y w i t h f r e s h l y d i s t i l l e d d i e t h y l ether (3 χ 500 mL). The ether was then concentrated t o g i v e the v o l a t i l e o i l as f o r the hexane e x t r a c t s . D i r e c t Vapor Analyses. Samples of f r e s h f i g or rehydrated dry f i g (100 g) were enclosed i n a wide mouth Erlenmyer f l a s k (250 mL) and the f l a s k covered w i t h aluminum f o i l . Samples of vapor (10 mL) from above the f i g s was drawn up i n t o a c l e a n dry g l a s s s y r i n g e and i n j e c t e d d i r e c t l y i n t o the c a p i l l a r y GLC column ( c f . _3). T h i s procedure was used f o r both the c a p i l l a r y GLC-mass spectrometry analyses and the q u a n t i t a t i v e a n a l y s e s . Q u a n t i t a t i v e analyses were made by comparison of peak areas w i t h those from vapor samples above known c o n c e n t r a t i o n s of the compounds i n water solution. C a p i l l a r y GLC-Mass S p e c t r a l (GLC-MS) A n a l y s i s . T h i s was c a r r i e d out u s i n g a 150 m long by 0.64 mm i . d . Pyrex g l a s s c a p i l l a r y column coated w i t h Carbowax 20-M. The column was h e l d a t 50°C f o r 30 minutes a f t e r i n j e c t i o n and then temperature programmed a t 1°/minute t o 170°C and h e l d at t h i s

Teranishi and Barrera-Benitez; Quality of Selected Fruits and Vegetables of North America ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

4.

BUTTERY ET AL.

Raisin and Dried Fig Volatile Components

31

upper l i m i t . A s i n g l e stage L l e w e l l y n - L i t t l e J o h n s i l i c o n e rubber membrane separator was used t o couple the end of the c a p i l l a r y column t o the mass spectrometer (a m o d i f i e d Consolidated 21-620 c y c l o i d a l t y p e ) . E l e c t r o n i o n i z a t i o n was 70 eV. RESULTS AND DISCUSSION


Raisin Volatiles. Steam d i s t i l l a t i o n continuous e x t r a c t i o n of the r a i s i n s under reduced pressure gave a v o l a t i l e r a i s i n o i l which amounted to 5-10 ppm of the r a i s i n s . The o i l was analyzed by c a p i l l a r y GLC-mass spectrometry (GLC-MS). The a n a l y s i s was repeated w i t h v o l a t i l e o i l s from s e v e r a l d i f f e r e n t samples of r a i s i n s . F i g u r e I shows a GLC a n a l y s i s of t y p i c a l o i l . The r e s u l t s are l i s t e d i n Table I . Peak numbers corresponding t o the peaks i n F i g u r e I are shown i n the f i r s t column of Table I a l o n g s i d e the compound s name. Some i d e a of the approximate r e l a t i v e percentages of the components i n a t y p i c a l o i l ( c a l c u l a t e d from peak areas) i s a l s o l i s t e d i n Table I . The major compounds i n the r a i s i n v o l a t i l e o i l i n c l u d e the a l i p h a t i c a c i d s o c t a n o i c , nonanoic, hexanoic, heptanoic, and decanoic a c i d s as w e l l as 2-hexyl-3-methylmaleic anhydride ( p r e v i o u s l y i d e n t i f i e d by some of the authors, , nonanal, phenylacetaldehyde and 2 - p e n t y l f u r a n . The most unusual component i s 2-hexyl-3-methylmaleic anhydride. Anhydrides are u s u a l l y hydrolyzed by water and are not l i k e l y t o occur i n foods because most foods have h i g h c o n c e n t r a t i o n s of water. C o n d i t i o n s i n d r i e d foods are a p p a r e n t l y , however, s u i t a b l e f o r the s t a b i l i t y and p o s s i b l y the formation of anhydrides. I t i s s u r p r i s i n g that t h i s anhydride s u r v i v e s the vacuum steam d i s t i l l a t i o n i s o l a t i o n procedure although the r e l a t i v e l y low temperature (ca. 50°C) and l i k e l y r a p i d t r a n s f e r t o the hexane s o l v e n t are probably favorable. Another unusual component i s the potent odorant l - o c t e n - 3 one which has been r e p o r t e d t o have a mushroom-metallic aroma and has been found i n cooked mushroom (5) and a r t i c h o k e (6). The major components, except f o r phenylacetaldehyde and p o s s i b l y 2-hexyl-3-methylmaleic anhydride, seem t o be d e r i v e d from o x i d a t i v e l i p i d breakdown i n common w i t h the v o l a t i l e s o f many other foods and p l a n t m a t e r i a l s . Eleven of the compounds i n Table I had been i d e n t i f i e d p r e v i o u s l y i n r a i s i n s by Ramshaw and Hardy ( J _ ) . These p r e v i o u s l y i d e n t i f i e d compounds have been noted on Table I (see f o o t n o t e d ) . The r e l a t i v e q u a n t i t a t i v e p a t t e r n found i n the present work seems t o be q u i t e d i f f e r e n t from that found by Ramshaw and Hardy. T h i s d i f f e r e n c e may be due t o the method and degree of d r y i n g used. Ramshaw and Hardy analyzed A u s t r a l i a n r a i s i n s that had been d r i e d t o 10% moisture whereas C a l i f o r n i a r a i s i n s are d r i e d to ca. 14%. The A u s t r a l i a n r a i s i n s 1



180

TIME IN MINUTES

60

Figure 1. Capillary GLC analysis of the vacuum steam volatile oil of raisins. GLC conditions are described in text.

120


4.

BUTTERY E T A L .

33


TABLE I Compounds I d e n t i f i e d i n the Vacuum Steam V o l a t i l e O i l of R a i s i n s .


Peak No. Fig. I

Compound

3

C h a r a c t e r i s t i c Mass S p e c t r a l Ions b

Alkanals 1 Hexanal^ 7 Heptanal 12 Octanal 22 Nonanal 36 Decanal

Kovat's R e l . GLC % Index

44, 44, 43, 57, 57,

56, 72, 82, 67, 100 70, 81,86 , 96, 114 44, 84, 100, 110, 128 44, 98, 82, 114, 142 44, 82, 112, 128, 156

1108 1190 1290 1390 1500

1.5 0.3 0.2 5.4 1.2

41, 41, 41, 41, 43, 41,

42, 55, 69 , 55, 83, 70 , 55, 70, 83, 70, 83, 96 , 70, 83,97 , 70, 83,97 ,

1230 1330 1430 1530 1630 1740

0.1 2.1 2.7 1.7 2.0 1.2

Alkadienals 34 (Ε,Ε)-2,4-Heptadienal 52 (E,E)-2,4-Nonadienal 56 (Ε,Ζ)-2,4-Decadienal 58 (Ε,Ε)-2,4-Decadienal

81, 39, 53, 81, 41,67, 81, 41,67, 81, 41,67,

1480 110, 67, 95 95, 138, 109 1660 95, 152, 123 1740 95, 152, 123 1790

1.7 0.4 0.2 2.0

Alkenals 6 (E)-2-Hexenal 16 (E)-2-Heptenal 26 (E)-2-0ctenal 38 (E)-2-Nonenal 48 (E)-2-Decenal 55 (E)-2-Undecenal d

d

83, 98 68, 112 97, 126 111, 140 110, 154 121, 168

Alkenones 14 l-0cten-3-one

55, 70, 43 97, 83, 111

1290

0.2

A l k a n o l s and A l k e n o l s 29a l-0cten-3-ol Octanol 41a 50 Nonanol 57 Decanol

57, 56, 56, 70,

72, 42, 70, 42,

85 81, 7C », 31, 42,31, 83 >, 31,

1420 1530 1630 1740

2.6 1.7 1.6 0.3

Alkanoic Acids 61 Hexanoic a c i d 64 Heptanoic a c i d 68 Octanoic a c i d 70 Nonanoic a c i d 71 Decanoic a c i d

60, 60, 60, 60, 60,

73, 73, 73, 73, 73,

57 45, 55, 87 », 45, 87, 101 55 », 85, 101, 115 45 », 115, 129, 158 45 57,129, 87, 172

1880 1990 2100 2220 2330

0.5- -4.4 0.5- -4.0 4--8.4 3--5.5 1--1.9

99, 84, 98, 97,

110 112 126 112


34

QUALITY OF

SELECTED

FRUITS A N D

VEGETABLES

Table I continued Terpenoids 43 (E)-2-Methy1-2,4heptadien-6-one 52 a l p h a - T e r p i n e o l 62 Geranylacetone

109, 43, 81, 53, 124, 79 59, 93, 81, 121, 136, 139 43, 69, 93, 136, 151, 19±


d

1590 1710 1850

0.1 0.4 1.4

Benzene, Naphthalene and Furan Compounds 9 2-Pentylfuran 81, 53, 138, 39, 95, 68 1240 3.4 29 Furfural 39, 96, 95, 67, 42, 50 1450 0.5 35 2-Acetylfuran 95, Π 0 , 39, 68, 53, 51 1490 1.0 36 Benzaldehyde 77, 105, 106, 51, 50, 39 1520 0.8 41, 5 - M e t h y l f u r f u r a l 110, 109, 53, 39, 81, 95 1560 2.2 47 Phenylacetaldehyde 91, 92, 120, 65, 39, 51 1650 4.0 53 Naphthalene 1_28, 64, 51, 63, 102, 77 1690 0.4-2.0 59 2-Methylnaphthalene 142, 141, 115, 71, 57.5, 63 1800 0.3 65 Dimethylnaphthalene _156, 141, 155, 115, 128, 76 2000 0.2 d

d

d

d

0

Others 69 44

2-Hexyl-3-methylmaleic anhydride 126, 43, 98, 67, 140, 196 N - E t h y l - 2 - f o r m y l p y r r o l e 123, 94, 108, 39, 66 e

a

2090 1600

f

5.0 1.0

Mass spectrum (complete spectrum) and K o v a t s GLC r e t e n t i o n index of a l l compounds l i s t e d are c o n s i s t e n t w i t h that of a u t h e n t i c samples, except f o r e. Not n e c e s s a r i l y the most i n t e n s e ions but 5 of those considered the most c h a r a c t e r i s t i c f o r t h a t compound. Ions i n descending order of i n t e n s i t y w i t h the most i n t e n s e i o n f i r s t and molecular i o n underlined. K o v a t s index f o r the Carbowax 20-M coated Pyrex c a p i l l a r y e s c r i b e d i n the experimental s e c t i o n . P r e v i o u s l y i d e n t i f i e d i n r a i s i n s by Ramshaw and Hardy, 1969. No a u t h e n t i c sample a v a i l a b l e . Mass spectrum c o n s i s t e n t w i t h p u b l i s h e d data ( 8 ) . c

f

e


4.

BUTTERY E T A L .


35

had showed a much greater r e l a t i v e amount of sugar degradation products such as f u r f u r a l and b i a c e t y l . I t i s i n t e r e s t i n g that Ramshaw and Hardy (1) i d e n t i f i e d a methylformylpyrrole whereas l - e t h y l - 2 - f o r m y l p y r r o l e was found i n the present work.


Fig Volatiles. The vacuum steam v o l a t i l e o i l of d r i e d f i g amounted t o 5 ppm of the d r i e d f i g . V o l a t i l e o i l s from s e v e r a l d i f f e r e n t samples of d r i e d f i g s were i s o l a t e d and analyzed by GLC-MS. Figure I I shows a GLC a n a l y s i s of a t y p i c a l d r i e d f i g v o l a t i l e o i l . Table I I l i s t s the components i d e n t i f i e d and compares the amounts found w i t h those found i n the present work i n f r e s h f i g s of the same v a r i e t y . Mass s p e c t r a l and GLC r e t e n t i o n data o f compounds a l r e a d y l i s t e d i n Table I are not repeated. Data f o r a d d i t i o n a l compounds have been i n c l u d e d i n Table IIA. The e t h a n o l , e t h y l a c e t a t e , methyl a c e t a t e and acetaldehyde had been found i n f r e s h f i g s by previous workers ( 2 ) . These are by f a r the most abundant v o l a t i l e components i n the f r e s h f i g . In the present work these very v o l a t i l e components were analyzed (GLC-MS) u s i n g d i r e c t i n j e c t i o n of the vapor above the f i g s onto the g l a s s c a p i l l a r y column. As much as 0.5% ethanol was found i n some samples of good q u a l i t y f r e s h r i p e f i g s . There was cons i d e r a b l e v a r i a t i o n , however. Other e s t e r s reported i n the previous study (2) were not detected u s i n g the methods of the present study. The e t h a n o l , e t h y l and methyl acetates and acetaldehyde might be formed by fermentation o c c u r r i n g i n the f r e s h f i g . This fermentation i s not apparent from the appearance and f l a v o r of the f i g which appear q u i t e normal and " f r e s h " . The very v o l a t i l e fermentation components discussed above seem to be l a r g e l y l o s t i n the dry f i g . The major component o f the d r i e d f i g v o l a t i l e o i l i s benzaldehyde. Other major components i n c l u d e the a l i p h a t i c a c i d s o c t a n o i c and nonanoic a c i d s . These a c i d s were a l s o major components of r a i s i n s and have aromas reminiscent of both r a i s i n s and d r i e d f i g s . They had p r e v i o u s l y a l s o been found as major components of d r i e d almond h u l l s (7^) which i s e s s e n t i a l l y a l s o a d r i e d f r u i t . The 2-hexy-3-methylmaleic anhydride common t o r a i s i n s and d r i e d almond h u l l s ( 4 ) was not detected i n d r i e d f i g s . Unusual components found i n the d r i e d f i g v o l a t i l e o i l i n c l u d e 3-phenylpropanal (dihydrocinnamaldehyde), l i n a l o o l oxide A (2-methyl-2-vinyl-5(2'-hydroxy-2 p r o p y l ) - t e t r a h y d r o f u r a n ) , l i n a l o o l oxide C ( 5 - h y d r o x y - 2 , 6 , 6 - t r i m e t h y l - 2 - v i n y l t e t r a h y d r o pyran) and N - e t h y l - 2 - f o r m y l p y r o l l e . The l a s t compound was a l s o i d e n t i f i e d i n r a i s i n v o l a t i l e s but i n both foods the i d e n t i f i c a t i o n was only by comparison w i t h a p u b l i s h e d spectrum (8) and no a u t h e n t i c sample was a v a i l a b l e . 1



18

Λ7

2X

Λ0

37

3^ 31

30

26 21

16

17

TIME IN MINUTES

2?

22

2X

^

10

8

5

Figure 2. Capillary GLC analysis of the steam volatile oil of dried figs. GLC conditions are described in text.

53

U9


w

>

Η

w ο w

4.

37


BUTTERY E T A L .

TABLE I I V o l a t i l e Components I d e n t i f i e d i n D r i e d and Fresh F i g s . Concentration i n f r e s h or d r i e d d r i e d i n f i g i n ppm


Peak 1· g.

-

Compound

3

ID Acetaldehyde Methanol Ethanol Methyl a c e t a t e E t h y l acetate Vacuum steam v o l a t i l e oil

2 3 8 15

-10 16 23 30 36

7-40 5 144 4 9 3

Alkanals Hexanal Heptana1 Octanal Nonanal

0.3 0.1 0.1 0.2

0.04 0.03 0.01 0.08

Alkenals (E)-2-Hexenal (E)-2-Heptenal (E)-2-0ctenal (E)-2-Nonenal (E)-2-Decenal (E)-2-Undecenal

0.1 0.2 0.05 0.1 0.04

-38 2a 3a 8a 22a 25

Alkanones and Alkenones 2-Hexanone 2-Heptanone 2-0ctanone (Ε,Ζ)-3,5-0ctadien-2-one (Ε,Ε)-3,5-Octadien-2-one

-

A l k a n o l s and A l k e n o l s Hexanol (Z)-3-Hexenol Heptanol

-

> > As f o r Table 1.

Insect Tests With R a i s i n and D r i e d F i g V o l a t i l e s . Some t e s t s have been begun w i t h t h e r a i s i n and d r i e d f i g v o l a t i l e s i n t h e i r a b i l i t y t o a t t r a c t the Indian meal moth ( P l o d i a i n t e r p u n c t e l l a ) and sawtoothed g r a i n b e e t l e (Oryzaephilus surinamensis) but no r e p o r t a b l e r e s u l t s have been obtained y e t . Fermented F i g s and D r o s o p h i l a A t t r a c t i o n . N i t i d u l i d s and D r o s o p h i l a spp. a r e a t t r a c t e d t o f i g s d u r i n g the r i p e n i n g phase i n the orchard. Experiments ( 9 ) , have shown that re-hydrated d r i e d f i g s allowed t o ferment f o r ca. 3 days were the most a t t r a c t i v e t o these i n s e c t s . Studies were c a r r i e d out i n the present work t o i d e n t i f y the components present i n the fermenting rehydrated f i g and t o t e s t these components a g a i n s t D r o s o p h i l a . The v o l a t i l e s found i n the fermented re-hydrated dry f i g were s i m i l a r t o those found i n other fermented products ( c f . _10). There was c o n s i d e r a b l e v a r i a t i o n w i t h d i f f e r e n t f e r mentation l o t s but i n g e n e r a l c o n c e n t r a t i o n s were o f the order o f the f o l l o w i n g : 0.4-2% e t h a n o l , 40 ppm acetaldehyde, 10 ppm e t h y l a c e t a t e , 20 ppm 2-phenylethanol, 1-2 ppm 2-phenylethyl a c e t a t e , 2.5 ppm 3-methylbutyl a c e t a t e , 30 ppm 2-methylpropanol, 100 ppm 3-methylbutanol, 4 ppm e t h y l hexanoate, 8 ppm e t h y l octanoate, 6 ppm e t h y l decanoate, 1 ppm e t h y l dodecanoate and c o n c e n t r a t i o n s roughly o f the order o f 1-10 ppm f o r the f r e e a c i d s o c t a n o i c , decanoic, undecanoic and dodecanoic. An undetermined amount o f a c e t i c a c i d was a l s o i d e n t i f i e d . A l l o f the compounds were t e s t e d a g a i n s t Drosophila u s i n g a l a b o r a t o r y o l f a c t o m e t e r . The only compounds t o show some a t t r a c t i v i t y were e t h a n o l , e t h y l a c e t a t e , acetaldehyde, a c e t i c a c i d (as a mixture, c f . 9>, 11) a l s o 2-phenylethanol, 2-phenylethyl a c e t a t e and 3-methylbutyl a c e t a t e . F u r t h e r s t u d i e s a r e i n progress w i t h v a r y i n g mixtures of these compounds.


4. BUTTERY ET AL. Raisin and Dried Fig Volatile Components

LITERATURE CITED 1. 2. 3. 4. 5.


6. 7. 8. 9. 10. 11.

Ramshaw, Ε. Η.; Hardy, P. J . J . Sci. Fd. Agric., 1969, 20, 619. Jennings, W. Food Chem. 1977, 2, 185. Buttery, R. G.; Teranishi, R. J . Agric. Food Chem. 1963, 11, 504. Buttery, R. G.; Seifert, R. M.; Haddon, W. F.; Lundin, R. E. J . Agric. Food Chem., 1980, 28, 1336. Cronin, D. Α.; Ward, M. K. J . Sci. Fd. Agric., 1971, 22, 477. Buttery, R. G.; Guadagni, D. G.; Ling, L. C. J . Agric. Food Chem. 1978, 26, 791. Buttery, R. G.; Soderstrom, E. L.; Seifert, R. M.; Ling, L. C.; Haddon, W. F. J . Agric. Food Chem. 1980, 28, 353. Stoll, Μ., Winter, Μ., Gautschi, F . , Flament, I . , Willhalm, Β., Helv. Chim. Acta 1967, 50, 628 Soderstrom, E. L. Unpublished work. 1978. Schreier, P. CRC Critical Reviews in Food Science and Nutrition, Nov. 1979, 59. Smilanick, J . M. J. Econ. Entomol. 1979, 72, 558.

RECEIVED

April

3,

1981.


41

Quality of Selected Fruits and Vegetables of North America - American

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