Effect of Different Thermal and Non-Thermal Treatments on Total Phenols and Antioxidant Content of Soybean

Abstract

Soybean is the most explored commodity for protein and fat as well as for obtaining products like soymilk and tofu. However, the presence ofanti-nutritional factors in soybean is not favorableand these are needed to be inactivated. Similarly, soybean is known for potential source of isoflavones, total phenolics and antioxidants.To inactivate anti-nutritional factorsdifferent treatments had been applied and consequently their corresponding effect on total phenolics (TP) and antioxidant capacity (AOC) were studied. High Pressure Processing (HPP), autoclave and microwave boiling treatments wereemployed to the soybean samples in soaked condition, and correspondingly their TP and AOC were estimated. HPP was not observed to affect the TP and AOC content significantly. The microwave treatment was observed to be affecting the TP and AOC but did not exhibit any severe effect while autoclave boiling lead to degradation of the bioactive by more than 50% and it was found to be severe. Conclusively, HPP was found to be suitable treatment to inactivate anti-nutritional factor and retain the bioactives like TP and AOC. The most elevated concentration of phenolic was acquired for HPP treatment at 400 Mpa for 10 min (1.88 mg/100g of the sample) and was almost similar to 400 Mpa for 5 min(1.87 mg /100g of the sample) and was observed that at higher pressure treatment time was not significant. The antioxidant capacity of the grains was similarly affected by the other processing techniques, but maximum was observed for raw sample (230.56 mg/100g of the sample). The autoclaveboilingimpaired severely total phenolics, and antioxidant capacity and it was observed to be 1.07mg/100 g of sample and 94.77 mg/100 g of the sample, respectively.