Abstract: Objective: To explore the effect of pre-treatment on anti-nutritional factors in home-made soybean milk. Methods: The retention rates of anti-nutritional factors including tannin, phytic acid, soponins and trypsin inhibitors in soybean milk made from soybeans after soaking, frying and germination treatments at room temperature or chilled condition were determined and also compared with that of soybean milk made from un-processed raw soybeans. Results: The retention rates of tannin and phytic acid, saponin and trypsin inhibitor activity in soybean milk made from germinated soybeans were 31.83%, 27.28%, 20.19% and 12.89%, respectively. The retention rates of tannin and phytic acid, saponin and trypsin inhibitor activity in soybean milk made from soaked soybeans at room temperature were 34.56%, 43.72%, 32.10% and 9.91%, respectively. Compared with the soaking and germination treatments, frying treatment revealed the weaker effect on lowering anti-nutritional factor level, but it still exhibited a significant difference with the control soybean milk made from un-processed raw soybeans. The retention rates of tannin and phytic acid, saponin and trypsin inhibitor activity in soybean milk made from fried soybeans were 64.05%, 54.59%, 28.78% and 10.88%, respectively. Conclusion: Compared with raw soybean, the retention rates of anti-nutrition factors in home-made soybean milk made from soybeans subjected to different treatments were significantly decreased. Moreover, the germination had the most obvious effect on the reduction of tannin and phytic acid and soaking treatment for 12 h revealed the best effect on the reduction of trypsin inhibitors.

Key words: pre-treatment, soybean milk, anti-nutritional factor, phytic acid, tannin, saponin, trypsin inhibitor