Modulating the properties and structure of a wheat starch-lauric acid system via modified soy protein isolate.
Modulation of starch digestibility in ternary systems involving starch, lipids, and proteins is an emerging research area. However, native soy protein isolate (SPI) restricts the formation of wheat starch (WS)-lauric acid (LA)-protein complexes because of its rigid globular structure. Therefore, this study investigated the impact of SPI modified via pH-shift (pHS), ultrasound (US), and high-pressure microfluidisation (HPM) on the characteristics and structure of the WS-LA system. The results showed that the WS-LA-protein systems containing modified SPI exhibited increased cooling peak viscosity, higher resistant starch (RS) and slowly digestible starch (SDS) contents, and more complexes with greater short-range order than those systems containing SPI. HPM-modified SPI increased SDS content in the WS-LA-protein systems by 41.0%, promoted denser complexes, increased relative crystallinity by 21.4%, and enhanced short-range order compared with SPI. These findings provide a theoretical basis for formulating functional foods with controlled starch digestibility.