Saltiness perception enhancement of myofibrillar protein gel via microwave treatment: Microwave promotes protein aggregation

This study aims to elucidate the mechanism by which microwave treatment enhances saltiness perception by altering the microstructure of myofibrillar protein gels, focusing on changes in gel microstructure, protein aggregation behavior, and molecular conformation. Myofibrillar protein gels with low ionic strength (0.2 mol/L) were prepared by intermittent microwave heating at 300, 500, 800, and 1000 W (water bath heating as control). On the condition that there are no significant differences in the cooking loss and sodium ion retention across the various treatments, protein gels heated at high power (800 and 1000 W) were perceived as saltier and formed more uniform and denser microstructures. Since the high power microwave exhibited the faster heating and aggregation rates, myofibrillar proteins became more prone to aggregation, forming aggregates that were more difficult to solubilize, with larger particle sizes and lower zeta potentials. Molecular conformation analysis revealed that the protein treated by microwave heating exhibited increased β-sheet formation, weaker hydrophobic interaction, but higher levels of disulfide bonds, thus facilitating the cross-linking of protein gels. Briefly, high-power microwaves changed protein conformation, promoting aggregation and resulting in the formation of a dense and uniform microstructure. This structural transformation shortened the diffusion pathways of sodium ions, significantly enhancing saltiness perception. Industry relevance: Meat products on the market typically contain high levels of salt. Microwave heating has the potential to create a dense microstructure in meat products, thereby enhancing saltiness perception. This study provides a scientific basis for applying microwave heating in salt reduction within the meat industry. • Microwave could modulate microstructure of protein gels. • Microwave with 800 and 1000 W enhanced saltiness perception of protein gels. • Microwave with 800 and 1000 W promoted aggregation and cross-linking of protein gels. • The denser microstructure eliminated the tortuosity effects of sodium diffusion. • Saltiness increment was related to the enhancement of protein aggregation.