Improving the textural and functional properties of soy protein isolate using dielectric barrier discharge (DBD) plasma-assisted pH-shifting

Abstract

This study aimed to improve the textural and functional properties of soy protein isolate (SPI) through a plasma-assisted pH-shifting method to create an alternative to meat products. The SPI was treated with DBD plasma for 0, 5, 10, and 15 min and then subjected to pH-shifting of 10 and 12 for 48 h before being adjusted to a neutral pH. The changes in the secondary structure of protein were evaluated using FTIR spectroscopy, free sulfhydryl measurement, and scanning electron microscopy (SEM). Heating the pH-shifted suspensions resulted in the formation of SPI gels with a densely cross-linked polymer-like network. Rheological and textural properties indicated that the pH-shifting treatment of SPI led to the production of stiff gels, so that the gel hardness increased from ~6.75 to ~13.28 N after 15 min plasma treatment at pH 12-shifting. The DBD plasma pretreatment negatively affected the functional properties of the SPI and decreased the solubility about 12 and 8% after 10 min plasma treatment at pH-shifting 10 and 12, respectively. The plasma-assisted pH-shifting offered a new approach for preparing SPI gel with enhanced water holding capacity, potentially expanding the range of applications for SPI in food formulations that require gelling and texturizing functions.