Development and characteristics of emulsion gels with microwave-assisted ferulic acid covalently modified soy protein: Structure, function and digestive properties

This work aims to investigate the effect of microwave-assisted ferulic acid (FA) covalently modified soy protein isolate (SPI), which acts as a stabilizer, upon the structural and functional properties of emulsion gel. The results showed that the microwave and FA covalently modified SPI could synergistically strengthen the colloidal properties of the system and improve its structure. The microwave-assisted FA covalently modified SPI maximized the absolute value of the ζ-potential (−33.5 ± 2.1 mV) and the thermal denaturation temperature (152.3 °C) of the system. In addition, the smaller system particle size (115.3 ± 3.3 nm) and the increase in irregular structure allowed the generation of stronger gel-like network structures in stable emulsion gel. The enhancement of uniform oil-water distribution and stability was also confirmed by LF-NMR and microstructure. The results of gastrointestinal digestion experiments showed that quercetin loaded on emulsion gels stabilized by SPI-FA-M promoted lipid hydrolysis and improved the bioaccessibility (from 20.0 ± 2.1% to 37.2 ± 1.5%) and stability (from 39.7 ± 1.3% to 78.3 ± 4.5%) of quercetin. Our findings provide a new perspective for understanding the potential applications of combined physical-chemical modified proteins as emulsion gels stabilizers in food delivery systems.