Production and Evaluation of Chelating Activity and Reducing Power of Protein Hydrolysates Obtained from Soy Protein Isolate

Somesynthetic antioxidants namely BHA and BHT are used as food additives in order to improve the quality and shelf life of food. Although these antioxidants exhibit higher antioxidant activity as compared to the natural antioxidants such as ascorbic acid, but in relation to their safety and related aspects to health, there is a cause for concern. Therefore the use of natural antioxidants to replace the synthetic antioxidants is considered as an important aspect and research concerned with this matter has been regarded quite important. Peptides obtained from proteins hydrolysis are examples of natural antioxidants that have been discussed in recent researches. In this study protein hydrolysate was produced from soya protein isolate using Alcalase 2.4l and the effect of different hydrolysis conditions such as temperature, time and enzyme/substrate ratio, on degree of hydrolysis and antioxidant activity of the product were investigated in a completely randomized design and then the Fe++ chelating activity and reducing power of protein hydrolysate was evaluated. The highest degree of hydrolysis was observed at 55°C after 210 minutes with the enzyme/substrate ratio of 90 Anson unit/ Kg substrate that was 30.27 %. Under these conditions, the Fe++ chelating activity reached its maximum concentration, whereas the Fe+++ reducing power showed the absorption of 0.15 that indicated lower value as compared to the highest obtained reducing power. The protein hydrolysate obtained from soya can act as a natural antioxidant with a high nutritional value and other biological properties and in appropriate concentrations might act as the synthetic antioxidants.