Effect Of Multiple Pretreatment Processes On Anti-nutritional Factors And Quality Of Soymilk

There are substances in soybean(Glycine max(L.)Merr.)that are not conducive to normal digestion and absorption by the human body.These substances are called anti-nutritional factors.In order to reduce the content of anti-nutritional factors in soymilk and to ensure good quality,raw soybean pulping was used as a control group,the effects of some conditions changed in the pre-treatment process on the anti-nutritional factors and nutritional quality of soymilk were investigated by using different soaking media and conditions.In addition,in this study,it was explored that subsequent main processing technology influenced the residual(activity)of anti-nutritional factors in soymilk and quality of soymilk and different sterilization methods influenced the shelf life of soymilk.Results were as follows:(1)In this paper,soybeans were pretreated by three methods of soaking,high temperature and germination and replacing different treatment media.Different treatments have different effect on each anti-nutritional factors.The results showed that soaking could effectively reduce activity of typsin inhibitor and content of phytic acid in soybean milk,among the three treatment methods.The effect of high temperature treatment on the reduction of trypsin inhibitor activity was extremely significant,and its content was reduced by 99.4% compared with the untreated group.Germination treatment has a good effect on reducing phytic acid content,but the quality of high temperature and germination treatment is poor.Consequently,soaking treatment is determined as the final pretreatment method.And,different soaking media could decrease contents of anti-nutritional factors in soymilk to different degree.The capabilities of reducing trypsin inhibitor activity are decreased from sodium bicarbonate solution to water to citric acid solution.The capabilities of reducing tannin content are decreased from citric acid solution to water to sodium bicarbonate solution.The capabilities of reducing phytic acid content are decreased from citric acid solution to water to sodium bicarbonate solution.In addition to anti-nutritional factors,the quality index of soymilk had been changed significantly.The results showed that the overall quality of the Na HCO3 soaking group was the best,except for the individual quality indicators(such as protein content),which was not significantly different from the water-immersed group(P>0.05),while the quality of the citric acid soaking group was the worst among the three groups.The Na HCO3 solution was selected as the soaking medium for orthogonal process optimization.The results showed that when the soaking temperature,time and the ratio of bean with water was 25℃,16 h and 1:4,respectively,and the Na HCO3 concentration was 0.45%,the anti-nutritional factor of soymilk had the best removal effect and the best quality.(2)In the two soymilk processing processes,the residual amount(activity)of the anti-nutritional factors in the soymilk produced by the method of squeezing after heating raw soymilk with okara was significantly lower than that of the soymilk produced by the method of squeezing homogenates before heating.And the activity trypsin inhibitor was only 3.03±0.12 TIU/mg;the content of tannin was 17.08±0.05 mg/100 mg.Although the content of phytic acid was significantly higher than that of the uncooked soymilk,the content was significantly lower than that of the method of squeezing after heating raw soymilk with okara.In terms of quality,the method of squeezing after heating raw soymilk with okara is superior.The protein content is 3.03 ± 0.15 g/100 g.(3)Different sterilization methods had significant effects on reducing content of anti-nutritional factors.In addition to tannin,the anti-nutritional factor content of soymilk after high temperature pressure sterilization was significantly lower than that of pasteurized soymilk.And the activity of trypsin inhibitor in the soymilk sample sterilized by high temperature pressure is only 2.50±0.30 TIU/mg.(4)In this paper,low anti-nutritional factors soymilk and tofu optimization were compared with traditional method soymilk and tofu.The results showed that except for tannin,the other anti-nutritional factors in the self-made low anti-nutritional factor soymilk were significantly lower than the traditional method soymilk(P<0.05),and the quality index of soybean milk was also better than the untreated soymilk.The trypsin inhibitor activity and phytic acid content in tofu made by homemade soymilk were significantly lower than those in traditional method tofu(P<0.05),but there was no significant difference in tannin content(P>0.05).In addition,there was no significant difference in quality(P>0.05).