Metabolic basis of quality deterioration in soybean variety Heihe 43 driven by storage time: Based on non-targeted metabolomics.

Soybeans are a high-quality plant-based food with both nutritional value and physiological activity, widely used in various fields such as food and feed. The quality evolution during soybean storage is a complex biological process regulated by multiple factors, but the mechanism of quality deterioration during long-term soybean storage is not yet fully understood. To reveal the underlying mechanism of soybean deterioration, this study constructed an accelerated storage simulation system under normal temperature and humidity conditions (20 °C, 65% RH) for 0-3 years, and explored the changes in the metabolic network during soybean storage and its intrinsic relationship with quality deterioration through non-targeted metabolomics. The results showed that with prolonged storage time, the brightness of soybeans significantly decreased, while the accumulation of free fatty acids (FFA) and formaldehyde (MDA) in the oil significantly increased, increasing by 364% and 134%, respectively. Metabolomics analysis identified a total of 903 differential metabolites, with lipids and lipid molecules accounting for the highest proportion. Compared with the control group, after storage, a total of 5 KEGG pathways were significantly enriched (p < 0.01), among which the linoleic acid metabolic pathway played an important regulatory role in soybean storage. The study on the correlation between significantly enriched lipid differential substances and lipid metabolites in this pathway found that there was a significant positive correlation between the relevant metabolites, with an overall correlation coefficient above 0.74, fully demonstrating the key regulatory role of linoleic acid metabolism in soybean oil oxidation. Lipoxygenase and cytochrome P450 have been found to play key regulatory roles in the linoleic acid metabolism pathway, with their key metabolites Linoleate, 13-HPODE, 13-KODE, 9-KODE, and 12,13-DHOME significantly accumulating during storage. Further analysis of the correlation between metabolites and soybean oxidation products, FFA, and malondialdehyde revealed a positive correlation, with a correlation coefficient above 0.83, providing potential evidence for early warning of quality deterioration. This study systematically analyzed the dynamic relationship between storage time and metabolic network, not only elucidating the key metabolic pathways of soybean quality deterioration during storage, but also providing a theoretical basis for establishing quality maintenance technology based on lipid metabolism regulation.