Insight into the spatial distribution and interaction model of heat-induced micro- and nano-starch/myofibrillar protein blends

Abstract

This work investigated the gelatinizing and hydration properties of raw and milled tapioca starches at micron and nano scale as well as their effects on gelation of myofibrillar proteins (MP) from Ctenopharyngodon idellus by analyzing rheology, texture and microstructure of heat-induced MP/starch blends. Milling induced starch granules damage to micron and nano scale, causing a fall in starch swelling power and a jump in water solubility. Among raw and milled starches, nano-starch had the best reinforcement effect on MP gel, i.e., MP/nano-starch showed the lowest critical gel concentration, highest G', strongest resistance to deformation and highest texture performance. Correlation analysis revealed that starch water solubility was responsible for the reinforced MP gel rather than starch swelling power. A schematic model was proposed for illustrating the interaction of starches and MP. All the blends had the ordered filamentous network as the basic skeleton, with some starches (granules and their fragments) in the voids or on the edge or surface of MP filaments as inert fillers, and some (chain segments) embedded in the filaments as active fillers. Almost all nano-starch were actively filled into the MP filaments to enhance the strength of filaments, thus achieving the best reinforcement effect on MP gel.