Abstract: In order to clarify the influence of Lactiplantibacillus pentosus fermentation on the structure of peanut proteins, changes in the structure of peanut protein isolate (PPI), arachin and conarachin before and after fermentation were studied. The results showed that L. pentosus fermentation significantly increased the free sulfhydryl content, surface hydrophobicity and denaturation temperature, and significantly reduced the β-folding content and denaturation enthalpy of arachin (P < 0.05). It reduced the free sulfhydryl content, surface hydrophobicity, and denaturation enthalpy, and significantly increased the degeneration temperature and α-helix content of PPI and conarachin (P < 0.05). Through particle size, potential and spectral analysis, we found that L. pentosus fermentation significantly improved the particle size and zeta potential of each protein component, and resulted in a red shift in their fluorescence peaks. In contrast to PPI and conarachin, the maximum fluorescence emission wavelength of arachin showed a 1.3 and 2.4 nm red shift, and arachin exhibited a 19.54% and 14.75% higher increase in thermal denaturation temperature, respectively. Thermal properties and scanning electron microscopic (SEM) analysis showed that arachin had maximum structural unfolding and higher thermostability after fermentation, indicating that L. pentosus fermentation is more likely to promote the molecular modification of arachin, and contributes to the gel modification of peanut proteins.

Key words: Lactiplantibacillus pentosus; peanut proteins; molecular structure; thermal properties; microstructure