Chapter 26
Effects of Gamma Irradiation on Chemical and Sensory Evaluation of Cabernet Sauvignon Wine Downloaded by UNIV MASSACHUSETTS AMHERST on September 9, 2014 | http://pubs.acs.org Publication Date: September 7, 1989 | doi: 10.1021/bk-1989-0405.ch026
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2,3
C. L. Caldwell and S. E. Spayd 1
Westinghouse Hanford Company, Richland,WA99352 Department of Food Science and Human Nutrition, Washington State University, Irrigated Agriculture Research and Extension Center, Prosser, WA 99350 2
Cabernet Sauvignon wines received gamma irradiation doses of 0, 0.6, 1.2 or 2.4 KGy and were stored at 21°C for up to 18 months. As radiation dose and storage time increased, total anthocyanin concentration decreased, while color density, hue and color age increased. Acetaldehyde concentration increased with increasing radiation dose and decreased as storage time increased. Sensory evaluation indicated no difference in color or astringency, but off-flavors were detected in wines given a 2.4 KGy dose. Use of gamma irradiation to rapid age Cabernet Sauvignon wines did not appear to be feasible. Wine aging involves a complex and little understood series of chemical reactions which are perceived by the consumer as an increase in flavor complexity, a shift from a bright red or red-purple associated with young red wines to a tawny red hue associated with well-aged red wines, and decrease in astringency. A major objective of most wine irradiation studies was to determine if irradiation can increase the rate of aging of wines. Wine irradiation experiments were reviewed by Singleton (1) and Mellinger (2). Gamma irradiation of wines was reported to increase acetaldehyde concentrations (3-7) and decrease color in red (5,7,8) and white (5,9) wines. Sensory evaluation of wines irradiated with 0, 1, 5 or 10 KGy showed a decrease in grape flavor and overall quality at the higher doses, while there were no differences in bottle bouquet, hotness, bitterness or astringency (5). Singleton (5) suggested that wine irradiation for rapid aging was worth investigation at doses of 10 KGy and probably less than 5 KGy. Therefore, this study was conducted to determine the effects of Address correspondence to this author. 3
0097-6156/89/0405-0337$06.00/0 c 1989 American Chemical Society
In Quality Factors of Fruits and Vegetables; Jen, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.
338
QUALITY FACTORS OF FRUITS AND VEGETABLES
gamma i r r a d i a t i o n o n t h e c o l o r a n d a c e t a l d e h y d e c o n c e n t r a t i o n o f Cabernet Sauvignon w i n e , t o a s c e r t a i n t h e r o l e o f s t o r a g e t i m e , and t o d e t e r m i n e t h e e f f e c t o f i r r a d i a t i o n on s e n s o r y a t t r i b u t e s .
Downloaded by UNIV MASSACHUSETTS AMHERST on September 9, 2014 | http://pubs.acs.org Publication Date: September 7, 1989 | doi: 10.1021/bk-1989-0405.ch026
Materials
and Methods
T h i r t y - e i g h t l i t e r s o f 1985 W a s h i n g t o n s t a t e C a b e r n e t S a u v i g n o n w i n e were o b t a i n e d f r o m e a c h o f two c o m m e r c i a l w i n e r i e s 8 months after crush. The w i n e s h a d c o m p l e t e d m a l o l a c t i c f e r m e n t a t i o n and were aged s e v e r a l months i n oak b a r r e l s . Wines were f i n e d w i t h g e l a t i n a t t h e r a t e o f 1 2 0 m g / 1 , s t o r e d i n 17 1 g l a s s c a r b o y s a t 10°C f o r o n e w e e k , c o l d s t a b i l i z e d a t 1 - 3 ° C f o r 12 d a y s , f i l t e r e d t h r o u g h 1 ym a n d 0 . 4 5 \im f i l t e r s ( G e l m a n , A n n A r b o r , MI) i n s e r i e s and b o t t l e d i n 375 m l g l a s s s c r e w c a p w i n e b o t t l e s . The b o t t l e d w i n e was t r a n s p o r t e d t o t h e U n i v e r s i t y o f W a s h i n g t o n , S e a t t l e f o r i r r a d i a t i o n w i t h a c o b a l t - 6 0 r e s e a r c h i r r a d i a t o r Μ. Κ . II (Brookhaven N a t i o n a l L a b o r a t o r y , NY). Dose l e v e l s u s e d were 0 , 0 . 6 , 1 . 2 and 2 . 4 KGy. The d o s e r a t e o f t h e i r r a d i a t o r was 206 Gy/hr. T h e w i n e w a s s t o r e d a t 10°C f o r o n e m o n t h p r i o r t o i n i t i a l c h e m i c a l a n a l y s e s a n d w a s t h e n s t o r e d f o r u p t o 18 m o n t h s a t 2 1 ° C . C o l o r was d e t e r m i n e d b y t h e method o f Somers and E v a n s ( 1 0 ) . A l l a b s o r b a n c e measurements were c o n d u c t e d u s i n g a Beckman ( I r v i n e , CA) D U - 6 s p e c t r o p h o t o m e t e r . A b s o r b a n c e o f t h e w i n e was measured a t 4 2 0 a n d 5 2 0 nm w i t h a 1 mm l e n g t h p a t h c u v e t t e . T h i r t y μ ΐ o f 20% sodium m e t a b i s u l f i t e s o l u t i o n were added t o a n o t h e r 2 m l o f w i n e . S a m p l e s w e r e m i x e d b y i n v e r s i o n a n d a l l o w e d t o s t a n d a t 20°C f o r 45 m i n a n d a b s o r b a n c e m e a s u r e d a t 5 2 0 n m . One h u n d r e d μ ΐ o f w i n e w e r e a d d e d t o 10 m l o f 1 M H C 1 , m i x e d a n d h e l d a t 10°C f o r 3 h r a n d a b s o r b a n c e m e a s u r e d a t 520 nm. A l l absorbance v a l u e s were a d j u s t e d t o a 10 mm l e n g t h p a t h a n d c o r r e c t e d f o r d i l u t i o n . Color e x p r e s s i o n s were c a l c u l a t e d as f o l l o w s : (1)
Color
density
(2)
C o l o r hue =
(3)
Total anthocyanins
(4)
Features
of
(a)
Age I
(b)
Age I I
(absorbance u n i t s )
[Abs^ ^
=
A
^
- (5/3) A b s ^
(mg/1)
(
= 20 [ A b s
s
20
4
S
Q
5 2 Q
2
)
+
A
* 520 ) S
] -(5/3)Abs
5 2 Q ( S Q 2 )
]
c h e m i c a l age = ^
5
2
= Abs
