Plant-based fat substitutes: soy protein hydrolysate-nano soy fibre co-assembled microgels embedded within oleogel matrices

Abstract

This study not only established a stable gel particle system through soy protein hydrolysate (SPH)-nano soy fibre (NSF) cross-linked gel network structure, which enhanced compatibility between gel matrices, but also realised composite microgels to form oleogels based on capillary forces to replace fats. The findings revealed that the addition of 2.0 wt% NSF changed both internal and external charges of composite microgel. Meanwhile, addition of NSF promoted unfolding of protein structure and exposure of more hydrophobic groups to polar environment. This led to a significant increase in hydrogen bonding, hydrophobic interactions, and disulphide bonds between proteins or between protein/nanofibre molecules, which enhanced dense network gel structure within the microgel. This endowed composite microgel with high gel strength, thermal stability, and good water-holding capacity, oil-holding capacity, antioxidant capacity. When formed into an oleogel by capillary force assembly with a secondary fluid (water), the oil loss rate was reduced to 12.6 %, and oxidative stability was enhanced. The proportion of PUFAs/SFAs in luncheon meat gradually increased as its substitution increased when oleogel was used as fat substitutes. The substitution of 50 % increased the content of α-linolenic acid and linoleic acid, which were two fatty acids essential to human health, from 14.65 % and 1.67 % to 25.90 % and 6.14 %, respectively. This indicated that oleogel improved the fatty acid nutritional composition of luncheon meat. This study enhances the refined design of gels and offers a novel approach to developing plant-based fat substitutes.