Carboxymethyl chitosan-induced modification of the structure and regulation of the thermal aggregation of Pleurotus eryngii protein fractions to improve gel properties.

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Citation abstract

In recent years, interactions between polysaccharides and proteins have been widely considered for use to improve protein gel performances. We previously found carboxymethyl chitosan (CMCS) can increase Pleurotus eryngii protein (PEP) gel properties, but the contributions of different key PEP fractions to overall gel formation remain unclear. The aim of this study was to investigate how CMCS affects the gel properties of PEP via intermolecular interactions with PEP fractions, including PEP1-1, PEP2-2, and PEP5-1. The results showed that CMCS reduced the turbidity of the PEP fractions and increased their solubility, suggesting that CMCS facilitated the formation of soluble aggregates. Additionally, fluorescence and ultraviolet spectroscopy confirmed that CMCS-PEP fraction interactions resulted in quenched fluorescence and decreased polarity of the microenvironment surrounding the PEP fractions. Moreover, Raman spectroscopy and scanning electron microscopy analyses indicated that CMCS increased the β-sheets in PEP1-1 and PEP5-1, and the β-turns in PEP2-2, forming ordered structures and dense network, leading to harder gels with better water-holding capacities. Finally, molecular docking revealed the presence of hydrogen bonds, salt bridges, and hydrophobic interactions between CMCS and PEP fractions. This study offers insights into the interactions between CMCS and PEP fractions, facilitating the application of PEP/CMCS in the food industry.