Effects of long-term storage on proteome and quality characteristics of soybean

Abstract

As an important source of plant protein and oil, soybean's protein quality degradation during storage can significantly affect processing characteristics and product quality. However, research on the molecular changes of soy protein under long-term storage is still limited. This study evaluated the changes in the basic quality of soy protein by measuring indicators such as color, particle size, Zeta potential, surface hydrophobicity, and turbidity, and combined proteomics analysis to investigate the molecular effects of long-term storage on protein quality. The results showed that when the simulated storage time reached 1 year, the a* value, b* value, particle size, and surface hydrophobicity of soy protein began to significantly increase ( p <0.05), while the L* value and absolute Zeta potential significantly decreased ( p <0.05). In the following 1-3 years of simulated storage, these degradation trends continued to intensify. Proteomic analysis identified a total of 8211 quantitative proteins. Compared with the control group, 186, 312, 378, and 365 differentially expressed proteins, as well as 50, 71, 75, and 88 pathways associated with quality deterioration, were identified after storage for 0.5, 1, 2, and 3 years, respectively. The changes in protein related pathways, from early storage of ribosome assembly, to autophagy and proteasome activation, accompanied by protein output inhibition in the middle stage, and then to enhanced and significantly enriched SNARE interactions in eukaryotes in the later stage, indicate that the functional damage and repair ability of soy protein gradually decrease with prolonged storage time. The changes in energy metabolism are caused by processes such as starch and sucrose metabolism, glycerol ester metabolism, glutathione metabolism, tricarboxylic acid cycle, and fatty acid biodegradation, which collectively lead to a decrease in soy protein quality. These changes reveal the molecular mechanism of irreversible deterioration of soy protein quality, providing a basis for protein stability analysis under long-term storage conditions.