Soybean protein isolate gel particles as foaming and emulsifying agents

• Soybean protein isolate (SPI) was used to prepare microgel particles.
• Microgel particles were made by break-down methods.
• SPI gel particles enhanced foam stabilizing properties of suspensions.
• SPI gel particles imparted emulsion stability against creaming and freeze-thawing.
• Steric repulsive effects of gel particles were highlighted.

In order to enhance functional properties of commercial soybean protein isolate (SPI), SPI microgel particles as foaming and emulsifying agents were studied. Microparticulation of heat-set SPI macrogels containing no added and various added salts was systematically carried out using a high-speed blender, an ultrasonicator and a high-pressure jet homogenizer. Among the tested conditions, the smallest gel particles were achieved via the high-pressure jet homogenization process under conditions of no added salts. Conversion of ordinary high molecular weight commercial SPI into the counterpart gel particles enhanced foam stabilizing properties of the suspensions and stability against creaming and freeze-thaw triggered instability of the emulsions, while the enhancement was not necessarily achieved for low-molecular-weight partially hydrolysed SPI. This can be attributed to the different steric repulsive effects of the gel particles.

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