Effect of Protein Oxidation on Functional Properties of Whey Protein Isolates
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Abstract:
The objective of this study was to explore the effect of protein oxidation on the functional and rheological properties of whey protein isolate (WPI). There were two different oxidation systems containing H2O2 (1 mmoL/L~20 mmoL/L) and FeCl3 (0.1 mmoL/L~2 mmoL/L) in this experiment. WPI was treated by the oxidation systems for 1 h, 3 h and 5 h respectively. The result revealed that the emulsifying activity of WPI decreased over 50% under the condition of 20 mmoL/L H2O2 for 5h. The gel hardness decreased 94.5% owing to 1mmoL/L FeCl3 for 3 h. Additionally, results also showed that the elasticity of WPI was decreased from 0.976 to 0.713 and 0.721 respectively by 20 mmoL/L H2O2 for 5 h and 1 mmoL/L FeCl3 for 3 h treatment. In addition, 20 mmoL/L H2O2 led to the decrease of elastic modulus value of WPI decreased from 8154 Pa to 5399 Pa and decrease of the complex modulus value from 10890 Pa to 6653 Pa. When 1 mmoL/L FeCl3 was used, the elastic modulus value declined from 8154 Pa to 4935 Pa and the complex modulus value was reduced from 10890 Pa to 6049 Pa. The spatial structure of proteins severely affected at the long time oxidizing conditions of high concentration. Therefore the functional properties and the gel texture of WPI were damaged significantly. Thus, protein oxidation should be avoided as much as possible in actual production for maintaining the nature characteristics of WPI, thereby preventing nutrient losses and promoting application value .
