Structural characterization and physicochemical properties of protein extracted from soybean meal assisted by steam flash-explosion with dilute acid soaking

- Effect of SFE-acid soaking pretreatment on protein structure was studied.
- The pretreatment changes the molecular weight distribution of SPI.
- Acid soaking treatment only induced the loss of tertiary structure of SPI.
- SFE treatment dramatically affected second structure of SPI.
- The change of protein structure alters the physicochemical properties of protein.

The aim of this work was to analyze the influence of steam flash-explosion (SFE) with dilute acid soaking pretreatment on the structural characteristics and physiochemical properties of protein from soybean meal (SBM). The pretreatment led to depolymerisation of soy protein isolate (SPI) and formation of new protein aggregation through non-disulfide covalent bonds, which resulted in broader MW distribution of SPI. The analysis of CD spectroscopy showed that the SFE treatment induced minor changes in secondary structure, however, the intrinsic tryptophan fluorescence revealed that acid soaking and SFE treatment pronouncedly altered the tertiary structure of SPI. The protein zeta potential was shown to be increased after SFE treatment attributed to the changes in protein structure and the covalent coupling between carbohydrate and protein. These results contribute to clarifying the mechanisms of the effect of pretreatment on SPI structure, thus moving further toward implementing SFE in the processing chain of SPI.