Low moisture extrusion of soybean protein isolate: Effect of β-glucan on the physicochemical properties of the product

In this study, β-glucan(BG) was mixed with soy protein isolate (SPI) according to mass ratio of 0%, 1%, 2%, 3%, 4% and 5%, and the BG-SPI blends were subjected to low moisture extrusion (36%). The apparent properties, functional properties, and structural properties of BG-SPI extrudates were investigated. The results showed that the hardness decreased and then increased with the increase of BG addition, which was mainly influenced by the enhancement of HY-QY-DI (interactions between hydrogen bonds, hydrophobic interactions, and disulfide bonds). The addition of 5% BG promoted the formation of disulfide bonds (DI) and hydrogen bonds (HY), and thus increased the oil holding capacity (OHC) and cooking yield (CY) of BG-SPI extrudates. It also promoted the formation of HY and disrupted QY-DI (interactions between hydrophobic interactions and disulfide bonds), which reduced the water solubility index to increase nutrient retention during subsequent processing. In addition, BG and SPI in the extruder formed a compound with a large molecular weight, and the main forces that maintain this compound were DI and HY.