Abstract: AIM: To evaluate the allergenicity change of hydrolyzed cow's milk by proteases.METHODS: The range of molecular weight of different formulas was determined by fast protein liquid chromatogram (FPLC) after hydrolyzing the infant milk powder with pepsin, trypsin and self-prepared pancreatin (SPP), and the sensitivity of hydrolysis of formulas milk to protein antigen was assayed by active, passive cutaneous anaphylaxis in mice and the changes of sensitized intestinal permeability in mice were observed.RESULTS: Molecular weights reduced after the hydrolyzation of milk protein with hydrolases and the most effectively degradation reaction was taken by the hydrolyzation with SPP (MW <1 000, 92 %;1 000-10 000, 8 %).The vascular permeability induced by the challenge of the milk protein antigen in mice reduced in the cases of the hydrolysate of pepsin, trypsin and SPP.The inhibition ratio of immediate-type cutaneous hypersensitivity reactions were as follows:51 %(pepsin), 83 % (trypsin)and 86 % (SPP), the inhibition ratio of homogeneous passive cutaneous anaphylaxis were as follows:29 %(pepsin), 70 %(trypsin) and 82 % (SPP), and the inhibition ratio of heterogeneous passive cutaneous anaphylaxis were as follows: 34 %(pepsin), 70 % (trypsin)and 82 % (SPP).Furthermore, hydrolysis of SPP reduced the vascular permeability induced by the small intestine anaphylaxis and the inhibition ratio was 27 %.CONCLUSION: The allergenicity of milk protein reduces after the hydrolysis with SPP.

Key words: infant milk powder, hydrolase, allergenicity, pepsin, trypsin, pancreatin