Changes in the sugars, amino acids and organic acids of postharvest spermine-treated immature vegetable soybean (Glycine max L. Merr.) as determined by 1H NMR spectroscopy

Abstract 1H NMR spectroscopy was adopted to determine compositional changes (mainly sugars, organic acids and amino acids) involved in cold-stored immature soybean grains after exogenous spermine treatment. Significant changes of sugars, including sucrose, galactose, myo-inositol, glucose and fructose were detected in soybean after spermine treatment. As for the organic acids related to tricarboxylic acid cycle, the levels of malic and fumaric acids decreased but the level of citric acid increased. However, no significant changes were observed for amino acids in spermine-treated soybeans. By using metabolic profile analysis, a difference was observed between the aging of soybean grains as such and those treated with spermine. This study provides an insight into the accumulation of metabolites in postharvest immature soybeans after exogenous spermine-treatment. Graphical abstract