Loss of Flavor Compounds from Aseptically Processed Food Products

Chapter 17

Downloaded by UNIV OF MASSACHUSETTS AMHERST on June 1, 2018 | https://pubs.acs.org Publication Date: May 9, 1990 | doi: 10.1021/bk-1990-0423.ch017

Loss of Flavor Compounds from Aseptically Processed Food Products Packaged in Aseptic Containers A. P. Hansen and D. K. Arora Department of Food Science, North Carolina State University, Box 7624, Raleigh, NC 27695-7624

The l o s s of n a t u r a l f l a v o r compounds in a s e p t i c a l l y processed and packaged milk and cream and the aroma changes in the headspace of UHT milk were monitored during storage. The concentration of methanal, propanal, butanal and nonanal decreased over s i x months for two processes (138°C for 20.4 s and 149°C for 3.4 s ) . Total aldehyde concentration decreased over a s i x month storage p e r i o d . Headspace a n a l y s i s of UHT processed milk revealed a l o s s of higher molecular weight f l a v o r compounds at 12 week storage. The loss of flavor compounds may be due to the interaction with the packaging m a t e r i a l (low density polyethylene) and with the p r o t e i n s . The l o s s of f l a v o r compounds in UHT processed and packaged milk and cream v a r i e d from 50-97% over a 12 month storage p e r i o d . Food p a c k a g i n g i s u n d e r g o i n g enormous c h a n g e s due t o t h e shift i n consumer i n t e r e s t towards convenience foods. Among f o o d p a c k a g i n g m a t e r i a l s , t h e u s e o f p l a s t i c s i s e x p e c t e d t o i n c r e a s e by 55% by 1990 ( 1 ) . The m a r k e t s h a r e of f l e x i b l e and r i g i d p l a s t i c p a c k a g i n g i s e x p e c t e d t o i n c r e a s e from $19 b i l l i o n t o $44 b i l l i o n by t h e y e a r 2000 (2) . Since the approval of hydrogen peroxide f o r sterilizaion of polyethylene food-contact surfaces i n 1981, t h e r e has been an enormous p r o l i f e r a t i o n i n a s e p t i c processing and p a c k a g i n g of food products. Besides convenience, a s e p t i c p a c k a g i n g has r e s u l t e d i n i m p r o v e d 0097-6156/90/0423-0318S06.00/O © 1990 American Chemical Society Koros; Barrier Polymers and Structures ACS Symposium Series; American Chemical Society: Washington, DC, 1990.


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Loss of Flavor Compounds from Packaged Foods

product q u a l i t y and i n lower p a c k a g i n g / o p e r a t i n g cost. Milk-based products, fruit j u i c e s and juice drinks are t h e major a s e p t i c p r o d u c t s i n t h e m a r k e t ( 3 - 5 ) . More t h a n 50 U.S. companies a r e c u r r e n t l y m a r k e t i n g f r u i t j u i c e s and drinks in aseptic packages (6). Tomato-based p r o d u c t s , s o u p s , wine and m i n e r a l w a t e r a r e e x p e c t e d t o be i n t r o d u c e d soon ( 6 ) . The s a l e o f f r u i t j u i c e and j u i c e drinks i s estimated t o be $60 m i l l i o n by t h e y e a r 2000 ( 6 ) . The U.S. m a r k e t may have a volume o f o v e r 15 b i l l i o n a s e p t i c p a c k a g e s by t h e y e a r 2000 ( 6 ) . Most a s e p t i c f o o d s a r e packaged i n a v a r i e t y of p o l y m e r i c m a t e r i a l s . The p l a s t i c p o l y m e r s u s e d i n a s e p t i c packages are e i t h e r i n a pure or a coextruded form to optimize b a r r i e r properties. T h e s e p l a s t i c s a r e n o t as inert as metal and glass containers resulting in a s h o r t e r s h e l f l i f e f o r l a m i n a t e d p a c k a g e s when compared t o m e t a l and g l a s s c o n t a i n e r s . A v a r i e t y of i n t e r a c t i o n s such as permeability, migration, light penetration and sorption between p l a s t i c s and f o o d p r o d u c t s have been d e s c r i b e d ( 7 ) . The s o r p t i o n o f f l a v o r compounds by p o l y m e r i c m a t e r i a l s has n o t been e x t e n s i v e l y d i s c u s s e d . S o r p t i o n r e f e r s t o the s c a l p i n g o f f l a v o r s and aroma components o f f o o d p r o d u c t s by p l a s t i c s . F l a v o r s c a l p i n g may i n f l u e n c e the sensory q u a l i t y and the a c c e p t a b i l i t y of food products by the consumer. Most o f t h e a s e p t i c p a c k a g i n g i s done i n c o n t a i n e r s where a low d e n s i t y p o l y e t h y l e n e (LDPE) l a y e r comes i n contact with the food p r o d u c t . I t has been shown t h a t LDPE f i l m does n o t p r o v i d e a good b a r r i e r t o t h e l o s s o f f l a v o r compounds. M o r r i s Salame (8) r e p o r t e d 71% and 66% absorption of non-polar and polar flavor compounds, respectively, by polyethylene (PE). The sorption of f l a v o r compounds i n t o PE f i l m i n c r e a s e d w i t h c a r b o n c h a i n length (9). Greater s o r p t i o n o f f l a v o r compounds was observed i n l e s s c r y s t a l l i n e PE f i l m , which suggested t h a t h i g h c r y s t a l l i n e f i l m s may r e d u c e f l a v o r compound s o r p t i o n i n t o t h e PE. Kwapong and H o t c h k i s s (10) r e p o r t e d t h a t d - l i m o n e n e was absorbed to a higher degree than benzaldehyde, citral and ethylbutyrate i n t o LDPE and ionomer r e s i n ( S u r l y n ) . Meyers and H a l e k (11) reported 30-40% l o s s i n hydrocarbon terpenes and 10% loss in o x y g e n a t e d t e r p e n e s when e x p o s e d t o LDPE. Mannheim e t a l . (12) r e p o r t e d a 25% r e d u c t i o n i n d-limonene content over 14 d a y s i n o r a n g e j u i c e s a m p l e s c o n t a i n i n g LDPE s t r i p s . Marcy et al. (13) reported lower flavor scores in concentrated o r a n g e j u i c e and c o n c e n t r a t e d orange d r i n k s t o r e d i n a s e p t i c f l e x i b l e bags. R e c e n t l y , C h a r a r a (14) r e v i e w e d s o r p t i o n o f flavor compounds i n t o p a c k a g i n g m a t e r i a l s . T h i s comprehensive r e v i e w showed t h a t p o l y m e r i c materials in contact with f o o d p r o d u c t s c a u s e d a l o s s o f f l a v o r compounds i n f o o d p r o d u c t s and model f o o d s y s t e m s . Low l e v e l s o f f r u i t p u l p content i n j u i c e r e s u l t e d i n higher a b s o r p t i o n of f l a v o r

Koros; Barrier Polymers and Structures ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

319


320

BARRIER POLYMERS AND STRUCTURES

compounds ( t e r p e n e h y d r o c a r b o n s ) and t h a t t h e d e g r e e o f absorptivity depended upon the nature of the flavor compounds. In dairy products the lipid component is an i m p o r t a n t c o n t r i b u t o r o f d a i r y f l a v o r . Compounds s u c h as mono- and d i - c a r b o n y l s and v o l a t i l e f a t t y a c i d s impart f l a v o r t o m i l k t h o u g h p r e s e n t o n l y i n low c o n c e n t r a t i o n s . S a t u r a t e d and u n s a t u r a t e d a l d e h y d e s and v a r i o u s k e t o n e s a f f e c t f l a v o r t h o u g h p r e s e n t i n c o n c e n t r a t i o n s o f ppm or ppb (15). Most o f t h e f l a v o r e d a s e p t i c f o o d s i n t h e m a r k e t a r e f o r t i f i e d w i t h e s s e n t i a l f l a v o r s t o compensate f o r any f l a v o r compounds l o s t d u r i n g p r o c e s s i n g and s t o r a g e . T h i s e m p i r i c a l technique o f f o r t i f i c a t i o n may work f o r some f o o d p r o d u c t s ; i n o t h e r s t h i s p r o c e s s may l e a d t o f u r t h e r d e t e r i o r a t i o n as the sorption process i s d r i v e n by a concentration gradient. Loss of one component in a complex f l a v o r m i x t u r e may r e s u l t i n a l o s s of flavor i n t e n s i t y o r a change i n f l a v o r n o t e s . D i f f e r e n t polymeric m a t e r i a l s w i t h h i g h aroma and flavor barrier p r o p e r t i e s are c u r r e n t l y being tested. Recently, i t was reported that ethylene vinyl alcohol (EVOH) c o e x t r u d e d containers resulted in no loss of e s s e n t i a l o i l and 24% l o s s o f v i t a m i n C i n o r a n g e j u i c e (16). Aaron Brody of S c h o t l a n d B u s i n e s s R e s e a r c h , I n c . ( 17) r e p o r t e d t h a t EVOH i m p r o v e d gas and aroma b a r r i e r p r o p e r t i e s and w i l l be u s e d e x t e n s i v e l y i n b a r r i e r f i l m s . To minimize flavor compounds sorption into packaging materials, impregnation of the polymeric layer with s u i t a b l e f l a v o r compounds has been s u g g e s t e d (7,17). The reports on sorption of flavor compounds by packaging materials suggest that more elaborate and detailed research on the i n t e r a c t i o n s between flavor compounds and p a c k a g i n g m a t e r i a l s i s needed t o p r o d u c e a s e p t i c p r o d u c t s h a v i n g a more s t a b l e f l a v o r p r o f i l e , a l o n g e r s h e l f l i f e and i n c r e a s e d consumer a c c e p t a n c e . In t h i s p a p e r we w i l l d i s c u s s the e f f e c t of UHT p r o c e s s i n g and s t o r a g e on t h e l o s s o f n a t u r a l f l a v o r s i n m i l k and cream and on t h e aroma c h a n g e s i n t h e h e a d s p a c e of aseptically processed and packaged milk during storage. M a t e r i a l s and

Methods

F r e s h m i l k and cream were o b t a i n e d from t h e N.C. State U n i v e r s i t y d a i r y f a r m and s t a n d a r d i z e d t o 3.25% f a t and 10% f a t , r e s p e c t i v e l y . M i l k was processed a t 149 °C f o r 3.4 s f o r s h o r t r e s i d e n c e t i m e (SRT) and 138°C f o r 20.4 s for l o n g r e s i d e n c e t i m e ( L R T ) . Cream was processed at 138°C f o r 20.4 s, a t 143°C f o r 7.8 s, a t 149°C f o r 3.4 s and a t 149°C f o r 20.4 s. A l l samples were p r e h e a t e d t o 78 °C. The milk was cooled in a No-Bac Aro-Vac ( C h e r r y - B u r e l l ) t o a f i l l i n g t e m p e r a t u r e o f 7°C. A s e p t i c p a c k a g i n g was a c c o m p l i s h e d by a T e t r a B r i k Model AB3-250



17.

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f i l l e r . M i l k and cream samples were s t o r e d a t 24°C and 40°C and a n a l y z e d m o n t h l y f o r up t o one y e a r . The m i l k and cream were c e n t r i f u g e d , and t h e f a t f r a c t i o n was removed. The f a t was e x t r a c t e d w i t h c a r b o n y l f r e e h e x a n e , and t h e f a t e x t r a c t was i m m e d i a t e l y r e a c t e d w i t h 2 , 4 - d i n i t r o p h e n y l h y d r a z i n e . The c a r b o n y l compounds formed r e s p e c t i v e 2 , 4 - d i n i t r o p h e n y l h y d r a z o n e s (2,4-DNPH). The h y d r a z o n e s were s e p a r a t e d i n t o m o n o c a r b o n y l s and t h e n further p u r i f i e d using thin l a y e r chromatography (18). Alkanal 2,4-DNPH were a n a l y z e d by gas chromatography u s i n g a 1.83 m g l a s s column ( i . d . 4 mm) p a c k e d w i t h 2% OV-1 on a c i d washed Chromosorb W (180-200 mesh) ( 1 8 , 1 9 ) . Headspace a n a l y s i s was conducted by gas c h r o m a t o g r a p h y a c c o r d i n g t o t h e method o f K e l l e r and K l e y n (20) w i t h t h e m o d i f i c a t i o n d e s c r i b e d by Nash ( 2 1 ) . Headspace analysis of milk samples was conducted biweekly. R e s u l t s and

Discussion

Loss o f F l a v o r Compounds i n UHT Processed Milk. The f l a v o r compound p r o f i l e s o f UHT p r o c e s s e d m i l k (138°C f o r 20.4 s, LRT) a r e shown i n F i g u r e 1 and F i g u r e 2 f o r 0 and 6 mo s t o r a g e a t 24°C, r e s p e c t i v e l y . Peaks 2, 3 and 5 corresponding to propanal, butanal and nonanal, respectively, disappeared over 6 mo. Similarly, UHT p r o c e s s e d m i l k (149°C f o r 3.4 s, SRT) s t o r e d f o r 6 mo a t 24° C showed significant decreases i n t h e peak areas u n d e r m e t h a n a l , p r o p a n a l and b u t a n a l w h i l e t h e nonanal peak d i s a p p e a r e d ( F i g u r e 3 and F i g u r e 4 ) . A t z e r o time SRT samples r e t a i n e d a h i g h e r c o n c e n t r a t i o n o f flavor compounds t h a n LRT s a m p l e s . The i n d i v i d u a l c o n c e n t r a t i o n s o f f l a v o r compounds i n UHT p r o c e s s e d m i l k a t LRT and SRT s t o r e d a t 24°C and 40°C i s shown i n F i g u r e 5 - F i g u r e 8. In LRT p r o c e s s e d m i l k , higher molecular weight aldehydes and total aldehydes d e c r e a s e d i n c o n c e n t r a t i o n . In a l l o t h e r i n s t a n c e s t h e r e was a n e t l o s s i n a l d e h y d e s . I n SRT p r o c e s s e d m i l k , a l l of the i n d i v i d u a l aldehydes decreased as w e l l as the t o t a l a l d e h y d e s a t b o t h 24°C and 40°C s t o r a g e . The l o s s o f a l d e h y d e s may be a t t r i b u t e d t o b i n d i n g by t h e p a c k a g i n g materials and by the proteins in milk which have u n d e r g o n e g r e a t e r c h e m i c a l and p h y s i c a l a l t e r a t i o n c a u s e d by t h e e x t e n d e d p r o c e s s i n g h o l d t i m e . The h e a d s p a c e a n a l y s i s o f a r o m a t i c compounds o f UHT p r o c e s s e d m i l k f o r t i m e z e r o i s shown i n F i g u r e 9. The f l a v o r compound p r o f i l e a f t e r s t o r a g e f o r 12 wk i s shown in Figure 10. The higher molecular weight flavor compounds have a l m o s t d i s a p p e a r e d . T h e s e r e s u l t s agree w i t h Shimoda e t a l . (9) who r e p o r t e d g r e a t e r s o r p t i o n o f flavor compounds into PE as carbon chain length i n c r e a s e d . F i g u r e 11 shows t h e f l a v o r compound p r o f i l e o f UHT p r o c e s s e d m i l k a t 24 wk. A t t h i s s t o r a g e p e r i o d t h e low m o l e c u l a r w e i g h t f l a v o r compounds were a l s o r e d u c e d .


321

322



1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

M E T H A N A L 2,4-DNPH P R O P A N A L 2,4-DNPH B U T A N A L 2,4-DNPH UNIDENTIFIED P E A K A N O N A N A L 2,4-DNPH INTERNAL S T A N D A R D UNIDENTIFIED P E A K Β UNIDENTIFIED P E A K C UNIDENTIFIED P E A K D UNIDENTIFIED P E A K Ε

10

V

R E T E N T I O N TIME

Figure 1. Time z e r o gas c h r o m a t o g r a m o f alkanal 2,4-DNPH f r o m UHT m i l k p r o c e s s e d a t 138 °C f o r 20.4 s (LRT). (Reproduced with p e r m i s s i o n from R e f . 18. C o p y r i g h t 1982 A m e r i c a n D a i r y S c i e n c e A s s o c i a t i o n . )

1. 2. 3. 4. 5. 6. 7.

M E T H A N A L 2,4-DNPH UNIDENTIFIED P E A K A INTERNAL S T A N D A R D UNIDENTIFIED P E A K Β UNIDENTIFIED P E A K C UNIDENTIFIED P E A K D UNIDENTIFIED P E A K Ε


F i g u r e 2. Gas c h r o m a t o g r a p h o f a l k a n a l 2,4-DNPH f r o m UHT m i l k p r o c e s s e d a t 1 3 8 ° C f o r 20.4 s and s t o r e d s i x mo a t 24°C (LRT). (Reproduced w i t h p e r m i s s i o n from Ref. 18. Copyright 1982 American Dairy Science Association. )


17. HANSEN & ARORA



M E T H A N A L 2,4-DNPH P R O P A N A L 2,4-DNPH B U T A N A L 2,4-DNPH UNIDENTIFIED P E A K A NONANAL 2,4-DNPH INTERNAL S T A N D A R D UNIDENTIFIED P E A K Β UNIDENTIFIED P E A K C 6 UNIDENTIFIED P E A K D UNIDENTIFIED P E A K Ε


Figure 3. Time z e r o gas c h r o m a t o g r a m of a l k a n a l 2 4-DNPH f r o m UHT m i l k p r o c e s s e d a t 149 °C f o r 3.4 s (SRT). (Reproduced with p e r m i s s i o n from R e f . 18. C o p y r i g h t 1982 A m e r i c a n D a i r y S c i e n c e A s s o c i a t i o n . ) f

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

M E T H A N A L 2,4-DNPH P R O P A N A L 2,4-DNPH B U T A N A L 2,4-DNPH H E X A N A L 2,4-DNPH UNIDENTIFIED P E A K A INTERNAL S T A N D A R D UNIDENTIFIED P E A K Β UNIDENTIFIED P E A K C UNIDENTIFIED P E A K D UNIDENTIFIED P E A K Ε


F i g u r e 4. Gas c h r o m a t o g r a m o f a l k a n a l 2,4-DNPH f r o m UHT m i l k p r o c e s s e d a t 1 4 9 ° C f o r 3.4 s and s t o r e d s i x mo a t 24°C (SRT). (Reproduced w i t h p e r m i s s i o n from Ref. 18. Copyright 1982 American Dairy Science Association.)


323

324

BARRIER POLYMERS A N D STRUCTURES


"o 5 METHANAL f ω

3

I

2 1

*

io-8

L

NONANAL

§0.6

ι

Φ

g 0.4 5,0.2

^7.5

PROPANAL

§6.0 σ> 7» 4.5 Φ

13.0

%, 1.0

100

£ g

60

I 40

*

TOTAL ALDEHYDES

8 0

h

n 20

^1.5

0 6 12 18 24 STORAGE TIME (WEEKS)

BUTANAL

S

3

6 12 18 24 STORAGE TIME (WEEKS)

F i g u r e 5. Changes i n a l k a n a l c o n c e n t r a t i o n s i n UHT m i l k p r o c e s s e d a t 138° C f o r 20.4 s and s t o r e d a t 24° C (LRT).



17. HANSEN & ARORA

"o

¥


METHANAL

5 4

£ω 3 Ε

°b 1.0

2

NONANAL

f 0.8

* 1

f0.6 o |0.4 3>Û.2 ^2.0

PROPANAL

f 1.6 §1.2

TOTAL ALDEHYDES

*fe 100

|0.8 ^0.4

0,60 |40 * 20 "b 1.0 f

0.8 L

S ω

0.6

BUTANAL

h 0 6 12 18 24 STORAGE TIME (WEEKS)

8 0.4 L

0 6 12 18 24 STORAGE TIME (WEEKS)

F i g u r e 6. Changes i n a l k a n a l c o n c e n t r a t i o n s i n UHT m i l k p r o c e s s e d a t 138° C f o r 20.4 s and s t o r e d a t 40° C (LRT).


325


326

BARRIER POLYMERS A N D STRUCTURES

METHANAL

«

3

jg 2

I

ΊΞ

1.0

f

0.8

I

0.6

1

"b 30

PROPANAL

g 24

-

§ 0.4 â

0.2

S18 α § 12 " *

6 -

1.5 I· I 0 6 12 18 24 STORAGE TIME (WEEKS)

F i g u r e 8. Changes i n alkanal concentrations i n UHT m i l k p r o c e s s e d a t 1 4 9 ° C f o r 3.4 s and s t o r e d a t 40°C (SRT) .


327


328


0

2

4

6

8

10 12 14 16 18 20 22 24 26 28 30 RETENTION TIME (MIN)

F i g u r e 9. Time z e r o g a s c h r o m a t o g r a m o f headspace v o l a t i l e s f r o m d i r e c t - p r o c e s s e d UHT m i l k .

J

I

L θ

J-

JL

Κ) 12 14

16 18 20 22 24 26 28 30

J.

RETENTION TIME (MIN) F i g u r e 1 0 . Gas c h r o m a t o g r a m o f h e a d s p a c e volatiles f r o m d i r e c t - p r o c e s s e d UHT m i l k s t o r e d 12 wk.



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F i g u r e 11. Gas c h r o m a t o g r a m o f h e a d s p a c e v o l a t i l e s f r o m d i r e c t - p r o c e s s e d UHT m i l k s t o r e d 24 wk.


329


330


Table

1.

Concentration of Flavor Compounds i n UHT Cream Over Twelve Months Storage

Flavor Compounds (umoles/g f a t )

Butanal

Months 0

3

6

9

12

0.65

0.66

0.65

0.52

0.33

0.21

0.21

0.21

0.23

0.26

0.36

0.25

0.18

0.14

0.09

1.14

1.13

0.98

0.68

0.27

2.00

1.56

1.10

0.71

0.26

2.18

1.55

1.07

0.80

0.46

8.06

5.28

3.21

1.90

0.24

4

(χ 10 ) Hexanal 4

(χ 10 ) Heptanal 4

(χ 10 ) Octanal 4

(χ 10 ) Nonanal 4

(χ 10 ) Decanal 4

(χ 10 ) Total Carbonyls 2

(χ 10 )


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HANSEN & ARORA

Loss of Flavor CompoundsfromPackaged Foods


The l o s s o f f l a v o r compounds may have been due t o b i n d i n g by t h e p a c k a g i n g m a t e r i a l s o r due t o i n t e r a c t i n g w i t h t h e chemical c o n s t i t u e n t s of foods. L o s s o f F l a v o r Compounds i n UHT P r o c e s s e d Cream. Table 1 shows the concentrations of flavor compounds in UHT p r o c e s s e d cream p a c k a g e d i n T e t r a B r i k p a c k a g e s o v e r 12 mo storage. The concentration of flavor compounds represents an average of four processes. Butanal c o n c e n t r a t i o n d e c r e a s e d 50%, a l d e h y d e s decreased 75-85% and t o t a l carbonyls (aldehydes, Ketones, enals, dienals, ketoacids, ketoglycerides, and dicarbonyls) decreased 97%. L o s s o f F l a v o r Compounds i n M o d e l S y s t e m s . Preliminary work conducted i n our laboratory showed sorption of a l d e h y d e s by LDPE u s e d i n a s e p t i c p a c k a g e s (Hansen, A. P.; Arora, D. K., North Carolina State University, R a l e i g h , u n p u b l i s h e d d a t a ) . The s o r p t i o n r a t e was related to concentration of aldehydes and to time, as both parameters increased so did the amount of flavor compounds s o r b e d i n t o t h e f i l m . A second mechanism, t h e possible interaction of aldehydes with amino a c i d s o r p e p t i d e s forming Schiff b a s e r e a c t i o n p r o d u c t s , was a l s o s t u d i e d . I n i t i a l r e s u l t s (Hansen, A. P.; Heinis J. J . , North Carolina State U n i v e r s i t y , R a l e i g h , u n p u b l i s h e d d a t a ) showed a d e c r e a s e in the aldehyde concentration when model systems c o n t a i n i n g v a r i o u s a l d e h y d e s and amino a c i d s were h e a t processed. Losses ranging from 8 to 50% of various a l d e h y d e s have been o b s e r v e d i n the p a s t e u r i z a t i o n of aldehydes and amino a c i d s m i x t u r e s in simulated milk ultrafiltrate. Summary F l a v o r i s one o f t h e most i m p o r t a n t a t t r i b u t e s o f a f o o d p r o d u c t because i t o f t e n d e t e r m i n e s whether the food i s accepted or rejected. Reduction of flavor compounds sorbed i n t o packaging m a t e r i a l may p r o d u c e more f l a v o r stable a s e p t i c food products. UHT processed milk and cream s t o r e d a t 24 °C and 40 °C showed d e c r e a s e in both aldehyde and total carbonyl concentrations. Further r e s e a r c h i s needed t o d e t e r m i n e t h e d e g r e e o f b i n d i n g o f flavor compounds to chemical constituents of food p r o d u c t s and t o p o l y m e r s u s e d i n a s e p t i c p a c k a g i n g . Acknowledgments The a u t h o r s would l i k e t o t h a n k M. S. Armagost a s s i s t a n c e i n p r e p a r a t i o n of t h i s manuscript.

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RECEIVED

November 14, 1989


Loss of Flavor Compounds from Aseptically Processed Food Products

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