46G-16 |
Antioxidant activity of whey and soy protein hydrolysates in cooked pork patties |
E. A. PEŅA-RAMOS, Animal Derived Food Department /Meat Science Lab, CIAD, A.C., P.O. Box 1735, Hermosillo, 83000, Mexico and Y. L. Xiong, Animal Sciences, Food Science Section, University of Kentucky, 206 W.P. Garrigus Bldg., Lexington, KY 40546. Antioxidants are widely used to minimize lipid oxidation in cooked muscle foods. Proteins, such as those from whey and soy, can act as natural antioxidants. It has been demonstrated in model systems that antioxidant properties of these proteins can be increased through hydrolysis with certain enzymes. However, the antioxidant potential of hydrolyzed proteins in cooked meats has not been assessed. The objective of this experiment was to evaluate the antioxidant activity of selected whey and soy protein hydrolysates in cooked pork patties. Whey protein isolate (WPI) was hydrolyzed with flavourzyme (W/F) for 1h or with protamex (W/P) for 6h. Preheated soy protein isolate (SPI) was hydrolyzed with chymotrypsin (S/C) or flavourzyme (S/F) for 0.5h. Antioxidative proteins, at a 2% level, were mixed into ground pork. Patties were cooked and stored at 4°C for 7 days. Lipid oxidation during storage was determined by measuring the concentration of conjugated dienes (CD) and thiobarbituric acid-reactive substances (TBARS). WPI, SPI, and all of their hydrolysates exhibited an inhibitory effect on lipid oxidation in cooked pork patties. No differences were observed between non-hydrolyzed WPI and W/F in their ability to decrease CD or TBARS concentration. However, W/P was more effective in reducing CD and TBARS formation (by 44% and 25%, respectively) when compared with non-hydrolyzed WPI (30.5% and 18% inhibition in CD and TBARS, respectively). Patties treated with S/F and S/C had lower concentrations of CD compared to non-hydrolyzed SPI. Hydrolysis did not change the ability of soy proteins to inhibit TBARS formation in the meat product. Hydrolysis with protamex improved the antioxidative activity of whey proteins, but hydrolysis was not essential to the antioxidative potential that already existed in non-hydrolyzed SPI. Soy proteins were generally more effective than whey proteins in inhibiting lipid oxidation in cooked pork patties.
Session 46G, Muscle Foods I
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