Oilseed Food Ingredients Used To Minimize Oxidative Flavor

Chapter 18

Oilseed Food Ingredients Used To Minimize Oxidative Flavor Deterioration in Meat Products

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Ki Soon Rhee Meat Science Section, Department of Animal Science, Texas A & M University, College Station, TX 22843-2471 Extensive studies have been conducted in our laboratory on utilization of oilseed food ingredients as antioxidants for meat products. Initial studies dealt with antioxidant activity, in model systems, of aqueous or alcoholic extracts of defatted flours, protein concentrates and protein isolates from glandless cottonseed, peanut and soybean. The model system studies were followed by evaluation of antioxidative effectiveness of oilseed ingredients when used in different categories of meat products. Glandless cottonseed ingredients which were higher in total phenolic concentration than other oilseed ingredients were also superior in antioxidative effectiveness in meat products. Furthermore, defatted glandless cottonseed flour incorporated into the coating of batter-breaded meat nuggets minimized oxidative flavor deterioration in the meat part of the nugget. Oxidative

Flavor

Deterioration

i n Meat

Products

L i p i d oxidation i s a major cause of f l a v o r d e t e r i o r a t i o n i n meat and meat products. A d d i t i o n a l l y , the o x i d a t i o n of l i p i d s may adversely a f f e c t the c o l o r o f f r e s h (raw) meat. Many s t u d i e s have r e p o r t e d a c l o s e i n t e r r e l a t i o n s h i p between l i p i d o x i d a t i o n and meat pigment o x i d a t i o n , i . e . , discoloration (1-4) . The o f f - f l a v o r s o f meat and meat products that are associated with l i p i d oxidation have been described as "warmed-over", "rancid", "oxidized", " s t a l e " , "cardboard", "painty", and " f i s h " f l a v o r s ( 5 - 7 ) . However, "warmed-over f l a v o r " i s the most o f t e n used d e s c r i p t i v e term f o r the f l a v o r defect o f cooked-stored meat ( 5 , 7 ) . Controlling l i p i d oxidation i n meat and meat products i s

0097-6156/92/0506-0223$06.00/0 © 1992 American Chemical Society In Phenolic Compounds in Food and Their Effects on Health I; Ho, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1992.


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PHENOLIC COMPOUNDS IN FOOD AND THEIR EFFECTS ON HEALTH I

more important now than ever before because the use o f precooked meat products by i n s t i t u t i o n a l foodservices, f a s t - f o o d o u t l e t s , d e l i c a t e s s e n s , e t c . , i s becoming more prevalent, along with the increased marketing of precooked f r o z e n meat entrees i n r e t a i l o u t l e t s . L i p i d oxidation occurs more r e a d i l y i n cooked meat or thermally processed uncured meat products. In f a c t , warmed-over f l a v o r can be detected i n uncured, cooked meat i n a few hours o f r e f r i g e r a t i o n (8). Oxidative f l a v o r d e t e r i o r a t i o n i n meat and meat products can be c o n t r o l l e d or minimized by using a variety of a n t i o x i d a n t s (9-11), including natural a n t i o x i d a n t s (10), and by vacuum packaging. O i l s e e d food i n g r e d i e n t s are one category of the n a t u r a l a n t i o x i d a n t s evaluated i n meat products. This chapter i s an overview of r e s e a r c h s t u d i e s conducted i n our l a b o r a t o r y t h a t were aimed at u t i l i z i n g o i l s e e d food i n g r e d i e n t s i n meat products as n a t u r a l antioxidants. Earlier

Studies

Extensive r e s e a r c h has been conducted s i n c e the e a r l y I960 s on the development and u t i l i z a t i o n of o i l s e e d food products f o r t h e i r economic, f u n c t i o n a l or n u t r i t i o n a l attributes. However, the a n t i o x i d a n t property that many o i l s e e d food i n g r e d i e n t s may possess has not been f u l l y u t i l i z e d i n formulation of food products, i n c l u d i n g meat products. In a previous l i t e r a t u r e review on the use of o i l s e e d i n g r e d i e n t s i n meat products (10), we found that many studies dealt with l i p i d oxidation i n meat p a t t i e s and loaves extended with o i l s e e d i n g r e d i e n t s , e s p e c i a l l y soy ingredients. However, i n most of these s t u d i e s , o i l s e e d i n g r e d i e n t s were added at very high l e v e l s , as high as 2530% i n the rehydrated s t a t e , f o r the purpose of extending the meat. The r e d u c t i o n of l i p i d o x i d a t i o n i n these s t u d i e s , t h e r e f o r e , was due i n l a r g e p a r t t o the meat d i l u t i o n e f f e c t exerted by the nonmeat i n g r e d i e n t s used at r e l a t i v e l y high l e v e l s . In order f o r an o i l s e e d ingredient to be named as an a n t i o x i d a n t f o r a food product, the i n g r e d i e n t when used at low l e v e l s should be able t o provide s u b s t a n t i a l antioxidant p r o t e c t i o n t o the product. We became i n t e r e s t e d i n a n t i o x i d a n t a c t i v i t y of o i l s e e d products i n meat systems i n the l a t e 1970 s, p r i m a r i l y because o f : (a) the research r e s u l t s from Dr. P r a t t ' s l a b o r a t o r y showing that the accumulation o f 2t h i o b a r b i t u r i c a c i d (TBA)-reactive substances i n cookeds t o r e d beef s l i c e s were s u b s t a n t i a l l y reduced when the s l i c e s were covered with aqueous e x t r a c t s (6.7% i n soy material) of soybeans and soybean food i n g r e d i e n t s rather than p l a i n water (12) and (b) a review by Hayes et al. (13) of a n t i o x i d a n t a c t i v i t y of soybean products. Following the r e p o r t o f P r a t t (12) on w a t e r - s o l u b l e antioxidant a c t i v i t y of soybeans, there was another key study that i n t e r e s t e d us. Sato et a l . (14) added a textured, defatted soy f l o u r product or l i q u i d cyclone-processed, defatted cottonseed f l o u r ( i . e . , pigment glands-removed, d e f a t t e d f l o u r from glanded cottonseeds) — at a 4% meat s u b s t i t u t i o n 1

,

In Phenolic Compounds in Food and Their Effects on Health I; Ho, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1992.

18. RHEE

Oilseed Food ingredients Used in Meat Products

225

l e v e l — t o ground beef l o a v e s . They found t h a t both o i l s e e d i n g r e d i e n t s decreased l i p i d o x i d a t i o n and warmedover f l a v o r development i n the cooked product during r e f r i g e r a t e d storage; however, much g r e a t e r a n t i o x i d a n t e f f e c t was shown by the cottonseed f l o u r .


Use

of Oilseed

Ingredients

as

Antioxidants

Model System S t u d i e s . Food i n g r e d i e n t s prepared from d i f f e r e n t o i l s e e d s were compared f o r t h e i r a n t i o x i d a n t a c t i v i t y i n model systems. Aqueous (15) and methanolic (16) e x t r a c t s were prepared from defatted f l o u r s , p r o t e i n concentrates and p r o t e i n i s o l a t e s from soybean, peanut and g l a n d l e s s cottonseed. Glandless cottonseed i s d i f f e r e n t from the r e g u l a r glanded c o t t o n s e e d i n that i t is e s s e n t i a l l y devoid of the pigment gland containing gossypol which i s t o x i c t o monogastric animals i n c l u d i n g humans. Glandless cottonseed kernels from the f i e l d may c o n t a i n i n s i g n i f i c a n t amounts (within the safe l i m i t ) of t o t a l gossypol (17). In our model system studies, l i n o l e a t e was reacted with metmyoglobin (MetMb), Fe -EDTA ( i n 1:1 molar r a t i o ) or raw beef homogenates, with oxygen uptake measured t o determine the r a t e of l i n o l e a t e o x i d a t i o n . The a n t i o x i d a n t a c t i v i t y o f the methanolic e x t r a c t o f each o i l s e e d i n g r e d i e n t was a l s o determined by i t s i n h i b i t o r y e f f e c t on autoxidation of safflower o i l (16). With aqueous e x t r a c t s , there were no o v e r a l l d i s t i n c t i v e d i f f e r e n c e s i n a n t i o x i d a n t a c t i v i t y among the three o i l s e e d types (15) . With methanolic e x t r a c t s , however, g l a n d l e s s cottonseed ingredients showed u n i q u e l y and c o n s i s t e n t l y h i g h e r a n t i o x i d a n t a c t i v i t y than peanut and soy i n g r e d i e n t s (16; Table I ) . Furthermore, the t o t a l phenolic content was a l s o markedly higher f o r the a l c o h o l i c e x t r a c t s o f g l a n d l e s s cottonseed i n g r e d i e n t s , and a n t i o x i d a n t a c t i v i t i e s o f methanol extracts of defatted flours and p r o t e i n concentrates from the three oilseed types were significantly c o r r e l a t e d with their total phenolic concentrations (16). More r e c e n t l y , a model meat system c o n s i s t i n g of water-extracted beef muscle residue plus MetMb, MetMb-H202r nonheme i r o n ( F e ) , or NADPH-dependent enzymic l i p i d p e r o x i d a t i o n system (18,19) was used t o obtain a d d i t i o n a l i n f o r m a t i o n on the a n t i o x i d a t i v e nature o f g l a n d l e s s cottonseed ingredients, s p e c i f i c a l l y defatted flour. Defatted glandless cottonseed f l o u r i n h i b i t e d the oxidation of l i p i d s i n the washed beef muscle r e g a r d l e s s of the c a t a l y t i c component or system (20; Table I I ) . However, the magnitude of i n h i b i t i o n by the cottonseed f l o u r v a r i e d depending on the thermal s t a t u s (raw or cooked) of the system as w e l l as c a t a l y t i c components. 2+

2 +

A d d i t i o n o f O i l s e e d I n g r e d i e n t s t o Meat. Frequently, model system r e s u l t s are d i f f e r e n t , q u a l i t a t i v e l y and/or q u a n t i t a t i v e l y , from r e s u l t s o f a c t u a l food p r o d u c t s because various constituents i n food products can i n t e r a c t


226


Table I. E f f e c t s of methanolic extracts of o i l s e e d ingredients on l i n o l e a t e oxidation catalyzed by Metmyoglobin (MetMb), Fe -EDTA and f r e s h beef homogenates and on autoxidation of safflower o i l 2+

% I n h i b i t i o n of l i n o l e a t e oxidation catalyzed b y D


Oilseed protein ingredient

3

MetMb

Fe2+-EDTA

Beef homogenates

% I n h i b i t i o n of autoxidation of safflower o i l

Defatted f l o u r s Cottonseed, glandless Peanut Soybean

67a 43b 35b

88a 57b 61b

51a 43b 4 6b

92 81 87

4 9a 37b 24c

91a 47b 31c

51a 28b 32b

82 74 68

53a 35b 23c

58a 32c 47b

53a 51a 48a

60 25 52

Concentrâtes Cottonseed, glandless Peanut Soybean

Isolâtes Cottonseed, glandless Peanut Soybean

SOURCE: Reprinted with permission from ref. 16. Copyright 1981. a

E x t r a c t equivalent to 0.1% (w/v) o i l s e e d ingredient i n the l i n o l e a t e oxidation system or 1.2g/10g safflower o i l . ^The data represent the means of two independent s e r i e s ( d u p l i c a t e determinations i n each s e r i e s ) of experiments for each o i l s e e d ingredient and c a t a l y t i c system. Means i n the same column within an ingredient form (defatted f l o u r , concentrate or i s o l a t e ) which are not followed by the same l e t t e r are s i g n i f i c a n t l y d i f f e r e n t (p2, F e and components o f enzymic l i p i d peroxidation: Raw and cooked systems 2 +

c

TBA n o . a f t e r storage at 4°C DGCF addition

Catalytic additive

3

13

0 day

3 days

d

% Inhibition by DGCF 0 day 3 days


Raw system MetMb e

MetMb + H 2 O 2

(1:0.l)

MetMb + H C>2

(1:0.25)

MetMb + H 0 2

(1:0.5)

MetMb + H 2 O 2

(1:1)

2

2

2

Fe + Fe

2 +

+ NADΡΗ + AD Ρ

0 .49 0 .33 1 .78 0 .38 2 .63 0 .39 0 .63 0 .36 0 .87 0 .36 1 .13 0 .61 1 .80 1 .22

w/o w/ w/o w/ w/o w/ w/o w/ w/o w/ w/o w/ w/o w/

0.,60 0.,39 1.,16 0.,33 3.,35 0.,42 2.,06 0.,41 2.,10 0.,40 1.,23 0.,49 2.,43 1.,37

33

35

79

72

85

88

43

80

59

81

46

60

32

56

37

50

55

61

54

70

45

74

76

84

70

76

43

61

Cooked system MetMb e

MetMb + H 0 2

(1:0.l)

MetMb + H 2 O 2

(1:0.25)

MetMb + H C>2

(1:0.5)

MetMb + H 2 O 2

(1:1)

2

2

Fe

2

Fe

+

2 +

+ NADΡΗ + AD Ρ

b

0 .89 0 .56 1 .23 0 .55 1 .36 0 .62 1 .13 0 .51 2 .34 0 .57 2 .09 0 .62 2 .19 1 .26

w/o w/ w/o w/ w/o w/ w/o w/ w/o w/ w/o w/ w/o w/

1..50 0.,75 1.,77 0..70 2..26 0,.68 2,.64 0..70 3..97 0,.62 3..15 0..76 3..54 1..40

a

2 +

L e v e l s o f c a t a l y t i c a d d i t i v e s : 4 mg MetMb/g; 3 μg F e / g ; 0.3 μπιοί NADPH/g; 0.3 μπιοί ADP/g. W/o: without DGCF; w/: with DGCF (2 6.5 mg DGCF/g). mg malonaldehyde/kg sample. TBA data f o r samples without DGCF were those r e p o r t e d p r e v i o u s l y (18). M o l a r r a t i o of MetMb t o H 2 O 2 . b

c

d

e



228


(22). Differences i n a n t i o x i d a t i v e e f f e c t i v e n e s s among the three o i l s e e d types were dependent on the degree of freshness of the raw meat m a t e r i a l . With f r e s h l y ground beef, a l l of the o i l s e e d ingredients t e s t e d were e f f e c t i v e i n preventing l i p i d o x i d a t i o n i n cooked p a t t i e s during 5 days of r e f r i g e r a t i o n , i r r e s p e c t i v e of the cooking endp o i n t i n t e r n a l temperature. However, when ground beef s t o r e d f o r 3 days at 4°C was used as the raw m a t e r i a l , g l a n d l e s s cottonseed i n g r e d i e n t s were s u p e r i o r t o soy or peanut i n g r e d i e n t s i n a n t i o x i d a t i v e e f f e c t i v e n e s s ; those p a t t i e s containing any type of glandless cottonseed showed no increase i n TBA v a l u e s even a f t e r 6 days o f r e f r i g e r a t i o n (Table III) . This confirmed what we had found i n model systems with methanolic e x t r a c t s of these o i l s e e d i n g r e d i e n t s (16), that i s , g l a n d l e s s cottonseed products have the greatest a n t i o x i d a t i v e e f f e c t . Sensory e v a l u a t i o n of the p a t t i e s prepared from f r e s h l y ground beef, which was conducted immediately a f t e r cooking (to an i n t e r n a l temperature of 74°C), revealed that p a t t i e s containing o i l s e e d ingredients were not s i g n i f i c a n t l y Table I I I . TBA values of a l l - b e e f and o i l s e e d ingredient-containing p a t t i e s prepared from ground beef stored at 4°C f o r 3 days TBA no. Cooked t o 70°C Product

3

0

All-beef Beef + defat. flour*> Cottonseed, glandless Peanut Soy Soy-textured Beef + c o n c e n t r a t e Cottonseed, glandless Peanut Soy Beef + i s o l a t e d Cottonseed, glandless Peanut Soy

Cooked t o 74°C

3 6 0 3 6 (Days at 4°C a f t e r cooking)

4,.1

5,.8

7,.6

4,.2

7..6

10.0

2..5 3..5 3..9 3..1

2 4 4 4

. .6 ,1 . .1 . .0

2, .5

4 .9 , 4 .6 . 3,.4

3,.0 3..2 3..7 2 .5 .

2..3 2..7 4 ,6 , 2..6

2.4 4.5 5.6 3.2

2..5 2,.6 3,.4

2,,4 2..6 3,.6

2,.5 2, .5 4 .1 ,

2,.7 2,.7 2 .5 ,

2..5 2..7 2, .1

2.2 4.4 3.0

2,.6 3,.2 3,.2

2,.5 3,.6 3,.3

2,.6 5,.1 3,.6

2,.8 3,.3 3,.3

2,.1 3,.7 4,.4

2.4 4.7 5.0

0

SOURCE: Adapted from Z i p r i n et a l . (21). A l l raw products were formulated t o contain 20% f a t . 10% as rehydrated product (3.3% dry o i l s e e d i n g r e d i e n t ) .

a

b



18. RHEE

Oilseed Food Ingredients Used in Meat Products

229

d i f f e r e n t from a l l - b e e f p a t t i e s i n a l l sensory a t t r i b u t e s evaluated. I t needs t o be emphasized t h a t a nonmeat i n g r e d i e n t t o be used i n a meat p r o d u c t s h o u l d be compatible s e n s o r i a l l y with that meat product and should not adversely a f f e c t the eating q u a l i t y of the meat product at the l e v e l used. Since our study on cooked beef p a t t i e s confirmed that g l a n d l e s s cottonseed i n g r e d i e n t s p r o v i d e d f a r s u p e r i o r antioxidant protection compared t o peanut o r soy ingredients, we d e c i d e d t o t e s t defatted glandless cottonseed f l o u r (DGCF; the l e a s t expensive g l a n d l e s s cottonseed p r o t e i n i n g r e d i e n t ) — at 1-3% l e v e l s based on the f i n a l product weight — i n r e s t r u c t u r e d beef roasts (23, 24) . When r e s t r u c t u r e d beef roasts made with added NaCl (0.75%), polyphosphate (0.5%) and water ( 3 % ) , with or without DGCF, were precooked and r e f r i g e r a t e d , both TBA values and sensory warmed-over f l a v o r scores were much lower f o r samples c o n t a i n i n g DGCF than those without DGCF. The use of DGCF at 1% and 2% l e v e l s had no adverse e f f e c t on p a l a t a b i l i t y of the r e s t r u c t u r e d beef product; however, when used at 3%, i t adversely a f f e c t e d t e x t u r e and f l a v o r of the product. A r e s t r u c t u r e d meat product i s made from lower-valued muscles, and s a l t (NaCl), polyphosphate(s) and water are u s u a l l y added i n the r e s t r u c t u r i n g process. We a l s o t e s t e d DGCF i n raw ground beef c o n t a i n i n g d i f f e r e n t amounts of NaCl, 0-2% (25, 26) . The NaCl l e v e l was i n c l u d e d as a v a r i a b l e because NaCl promotes l i p i d o x i d a t i o n (19) and processed meat products contain v a r y i n g amounts of NaCl. At each NaCl l e v e l , DGCF (2% or 3%) reduced l i p i d o x i d a t i o n and d i s c o l o r a t i o n i n raw ground beef p a t t i e s d u r i n g storage at both 4° and -20°C. The l i p i d - and c o l o r - p r o t e c t i n g e f f e c t s of DGCF were observed i n beef p a t t i e s containing r e l a t i v e l y small amounts of f a t , 8% (25) and 10% (26), as well as i n beef p a t t i e s containing a much higher amount of f a t , 20% (26) . At t h i s p o i n t , we conducted a study t o determine i f the DGCF would have any adverse e f f e c t on m i c r o b i a l growth i n ground beef stored under r e t a i l d i s p l a y c o n d i t i o n s (27) . Ground beef with or without 3% added DGCF was over-wrapped with oxygen-permeable p o l y v i n y l c h l o r i d e f i l m , as commonly done f o r r e t a i l ground beef, and d i s p l a y e d up t o 6 days i n a r e t a i l case. In contrast to the f i n d i n g s of many studies showing that meat extenders d e r i v e d from soybeans, u s u a l l y used i n ground meat at 10-30% (rehydrated b a s i s ) l e v e l s , o f t e n i n c r e a s e b a c t e r i a l counts of raw ground beef (28) , DGCF (not rehydrated) added to ground beef at 3% l e v e l s d i d not a d v e r s e l y a f f e c t the d i s p l a y l i f e i n terms of t o t a l aerobic plate counts. The e f f e c t o f DGCF on the composition of microorganisms (especially dominant microorganisms) d u r i n g the d i s p l a y was s i m i l a r t o the vacuum packaging e f f e c t f o r f r e s h beef c u t s , i . e . , L a c t o b a c i l l u s spp. c o n s t i t u t e d a major or dominant part of the m i c r o f l o r a of ground beef with added DGCF while Ρ seudomonas spp. or a combination of Pseudomonas and h e t e r o f ermentat i v e Lactobacillus spp. dominated the m i c r o f l o r a of ground beef with no DGCF.



230


Use o f O i l s e e d I n g r e d i e n t s i n Meat Accompaniments. The antioxidant property of o i l s e e d i n g r e d i e n t s can a l s o be indirectly utilized. The i n g r e d i e n t s can be i n c o r p o r a t e d i n t o l i q u i d media (such as gravy and sauce) f o r precooked meat products. Many frozen meat entrees (e.g., S a l i s b u r y steaks, roast beef s l i c e s with gravy, meat l o a f s l i c e s with sauce, etc.) used i n many f o o d s e r v i c e establishments and those a v a i l a b l e at r e t a i l o u t l e t s have some types of l i q u i d cover. We used g l a n d l e s s cottonseed, peanut and soy i n g r e d i e n t s ( d e f a t t e d f l o u r s , p r o t e i n concentrates, and p r o t e i n i s o l a t e s ) , i n conjunction with wheat f l o u r , to make gravies (29). When precooked beef p a t t i e s (100% beef) were covered with gravy p r e p a r a t i o n s with or without o i l s e e d i n g r e d i e n t s , t o simulate S a l i s b u r y steaks, and s t o r e d at 4°C, TBA values were much lower f o r the p a t t i e s covered with the gravy preparations c o n t a i n i n g o i l s e e d i n g r e d i e n t s than those without. No c o n s i s t e n t d i f f e r e n c e s among the o i l s e e d types were observed. In a d d i t i o n , hot water e x t r a c t s of the o i l s e e d i n g r e d i e n t s were t e s t e d as a cover l i q u i d (6% i n dry o i l s e e d i n g r e d i e n t ) f o r r e f r i g e r a t e d roast beef s l i c e s (29). TBA values were markedly lower f o r the beef s l i c e s covered with o i l s e e d i n g r e d i e n t e x t r a c t s than f o r those covered with p l a i n water, regardless of the o i l s e e d type or ingredient form (Table IV).

Table IV. TBA values of roast beef s l i c e s covered with aqueous e x t r a c t s of o i l s e e d food ingredients and stored at 4°C f o r 3 days Extract Defatted f l o u r H 0 (control) Cottonseed, glandless Peanut Soybean 2

TBA

no.

4.4 1.3 1.5 1.7

Concentrate H 0 (control) Cottonseed, glandless Peanut Soybean Isolate H 0 (control) Cottonseed, glandless Peanut Soybean 2

2

4.1 1.0 2.9 1.5 4.6 2.0 1.8 1.9

SOURCE: Reprinted with permission from ref. 29. Copyright 1981.

Use o f O i l s e e d I n g r e d i e n t s i n B a t t e r - B r e a d i n g . More r e c e n t l y , we became i n t e r e s t e d i n c o n t r o l l i n g o x i d a t i v e f l a v o r d e t e r i o r a t i o n i n batter-breaded meat products using o i l s e e d food i n g r e d i e n t s . A v a r i e t y of precooked/prepared,



18. RHEE

Oilseed Food Ingredients Used in Meat Products

231

batter-breaded meat products are c u r r e n t l y a v a i l a b l e i n r e t a i l o u t l e t s , and t h e i r f l a v o r freshness i s not always predictable. In a d d i t i o n , raw-frozen, batter-breaded muscle food products are widely used i n f o o d s e r v i c e . It was not c e r t a i n i f an a n t i o x i d a t i v e o i l s e e d i n g r e d i e n t incorporated i n t o the batter-breading system (rather than i n t o the meat formulation) would s i g n i f i c a n t l y protect the meat l i p i d s from o x i d a t i o n . I n i t i a l l y , DGCF and sunflower seed p r o t e i n i s o l a t e were incorporated i n t o b a t t e r used t o coat beef p a t t i e s ( 3 0 ) . Ground beef p a t t i e s coated with e i t h e r b a t t e r made of wheat f l o u r alone (control) or b a t t e r made with 1:1 blends of wheat f l o u r and DGCF (or sunflower seed p r o t e i n i s o l a t e ) were f r i e d i n commercial cooking o i l ( p a r t i a l l y hydrogenated soybean o i l ) . TBA values of the meat part of f r i e d p a t t i e s s t o r e d at 4°C f o r 5 days were reduced by more than 50% by the DGCF or sunflower i s o l a t e present i n the coating. While presence of DGCF i n b a t t e r had no adverse e f f e c t on the crust c o l o r o f f r i e d p a t t i e s , sunflower i s o l a t e d i s c o l o r e d the crust because of i t s dark greenish color. In t h e e n s u i n g s t u d i e s , DGCF was incorporated e i t h e r i n t o predust p l u s b a t t e r or i n t o r e s t r u c t u r e d pork muscle nuggets (31, 32) . Pork shoulders were r e s t r u c t u r e d i n t o nuggets (1.25-cm t h i c k ) with 0.5% NaCl, 0.25% polyphosphate and 3% water or with the three a d d i t i v e s plus 1.5% DGCF, and r e s t r u c t u r e d nuggets were batter-breaded with e i t h e r commercial c o a t i n g i n g r e d i e n t s or commercial c o a t i n g i n g r e d i e n t s plus DGCF (40% and 20% DGCF i n predust and dry b a t t e r mix, r e s p e c t i v e l y ) . The batter-breaded nuggets were p r e - f r i e d i n vegetable o i l without p r e s e r v a t i v e s and stored at e i t h e r 4°C (31, 32) or -20°C (32) . TBA values and sensory warmed-over f l a v o r scores determined on the p r e c o o k e d - r e f r i g e r a t e d products (31, 32) and TBA values on raw-frozen p r o d u c t s (32) i n d i c a t e d that o x i d a t i v e f l a v o r d e t e r i o r a t i o n i n b a t t e r breaded pork nuggets can be s u b s t a n t i a l l y reduced o r minimized by i n c o r p o r a t i n g the o i l s e e d i n g r e d i e n t i n t o e i t h e r the coating system or the meat. Data representing t y p i c a l r e s u l t s of refrigerated-reheated products are shown i n Table V. Heating Oilseed Protein Ingredients with Reducing Sugars t o Enhance A n t i o x i d a n t Effect. Many s t u d i e s have shown t h a t the nonenzymatic browning (Maillard) r e a c t i o n produces a n t i o x i d a t i v e substances (11) . However, i n the great majority of these studies, products r e s u l t i n g from the r e a c t i o n of an amino a c i d or a secondary amine with a reducing sugar were t e s t e d f o r antioxidant a c t i v i t y . We were interested i n documenting whether o r not nonenzymatic browning between o i l s e e d p r o t e i n i n g r e d i e n t s and a reducing sugar could enhance the antioxidant value of o i l s e e d i n g r e d i e n t s , and the extent of the enhancement, i f i t does. Defatted f l o u r s (54-63% p r o t e i n ) and p r o t e i n isolates (89-93% p r o t e i n ) prepared from glandless cottonseed, peanut and soybean were mixed with glucose i n a r a t i o of 1:1 by weight and heated at 100°C f o r up t o 6 hours. Antioxidant activity of e t h a n o l i c extract of the


232


Table V. TBA values and sensory warmed-over f l a v o r (WOF) scores f o r precooked, batter-breaded pork nuggets made with or without d e f a t t e d glandless cottonseed f l o u r (DGCF) i n the meat or coating that were reheated a f t e r 0 or 9 days of storage 4°C TBA Whole nugget

WOF

no. Meat alone

score

f

Whole nugget

e


Product (Meat/ coating)

0

9

0

Days

C/C C/E E/C E/E

a

a

a

b

1.3 2.7 1.2 1.5 1.0 l . l 0.9 l . l

0

9

9 Days

Days

b

c

b

c

1.1* 0.8 0.6 0.5 b

2.7 1.4

a

b

C

1.2C

d

d

0.9

a

5.0 4 .7 4.9 4.8 a

a

a

3. 9 4.4 4.7 4.5

b

a

a

a

SOURCE: Adapted from Rhee et a l . (31). ^Means w i t h i n the same column which are not followed by the same s u p e r s c r i p t l e t t e r are s i g n i f i c a n t l y d i f f e r e n t (p

Oilseed Food Ingredients Used To Minimize Oxidative Flavor

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