Abstract: To reduce the allergenicity of soybean milk powder, soybean milk after removal of okara was treated by ultra-high pressure (UHP) followed by restriction enzyme hydrolysis instead of the traditional wet process for producing soybean milk powder. Using one-factor-at-a-time and orthogonal array design methods, the optimum process parameters were determined as follows: 15 min UHP treatment at 320.00 MPa and then 60 min hydrolysis with 0.3 U/g of flavourzyme. The allergenicity of soybean milk powder produced under the optimized conditions was reduced by 88.09%, but it tasted slightly bitter. To improve the taste, further blending is needed. The combination of UHP and enzymatic hydrolysis synergistically significantly enhanced the in vitro protein digestibility and reduced the allergenicity of soybean milk powder. This synergistic effect was further confirmed by measurement of in vitro protein digestibility, protein dispersibility index and allergen content and SDS-PAGE analysis.

Key words: UHP-restriction enzyme hydrolysis treatment, soybean powder, allergenicity, solubility, in vitro digestibility, electrophoresis