Nuclear magnetic resonance spectroscopy and liquid chromatography–mass spectrometry metabolomics studies on non‐organic soybeans versus organic soybeans (Glycine max), and their fermentation by Rhizopus oligosporus

Abstract

Background Soybeans (Glycine max) are high in proteins and isoflavones, which offer many health benefits. It has been suggested that the fermentation process enhances the nutrients in the soybeans. Organic foods are perceived as better than non‐organic foods in terms of health benefits, yet little is known about the difference in the phytochemical content that distinguishes the quality of organic soybeans from non‐organic soybeans. This study investigated the chemical profiles of non‐organic (G, T, U, UB) and organic (C, COF, A, R, B, Z) soybeans (G. max [L.] Merr.) and their metabolite changes after fermentation with Rhizopus oligosporus. Results A clear separation was only observed between non‐organic G and organic Z, which were then selected for further investigation in the fermentation of soybeans (GF and ZF). All four groups (G, Z, GF, ZF) were analyzed using nuclear magnetic resonance (NMR) spectroscopy along with liquid chromatography–tandem mass spectrometry (LC–MS/MS). In this way a total of 41 and 47 metabolites were identified respectively, with 12 in common. A clear variation (|log1.5FC| > 2 and P < 0.05) was observed between Z and ZF: most of the sugars and isoflavone glycosides were found only in Z, while more amino acids and organic acids were found in ZF. An additional four metabolites clustered as C‐glycosylflavonoids were discovered from MS/MS‐based molecular networking. Conclusion Chemical profiles of non‐organic and organic soybeans exhibited no significant difference. However, the metabolite profile of the unfermented soybeans, which were higher in sugars, shifted to higher amino acid and organic acid content after fermentation, thereby potentially enhancing their nutritional value. © 2022 Society of Chemical Industry.

Profiling of Metabolites in a Fermented Soy Dietary Supplement Reinforces its Role in the Management of Intestinal Inflammation

“…[130,131] Other studies investigating fermented soy products using NMR techniques show similar effects; isoflavones were aglcyonated during fermentation, and that amino acids, SCFA, and other organic acids were produced with different spectra depending on fermentation time and production processes. [14,16,39,40,132] In our analysis, large increases in genistein and organic acid concentrations were seen, combined with decreases in the conjugated isoflavones. Interestingly in our analysis, a nuanced production of amino acids was evident, with decreases seen in some amino acids (e.g., leucine), combined with increases in others (e.g., tyrosine).…”

“…Soy (Glycine max) products are one of the most widely produced and consumed foods in the world, with an extensive range of derived products, known for their diverse applications in food miso, soy sauce) show higher levels of bioavailable aglycone isoflavones compared to raw or cooked soy foods. [14][15][16][17] Further microbiome-derived bioactivation of primary metabolites in some individuals is possible in the gut prior to absorption across the gut barrier, producing additional estrogenic molecules. [13] Other important soy chemical constituents can help further explain the favorable dietary effects seen in human populations.…”

“…[ 4,13 ] Specific fermented soy products (e.g., tempeh, miso, soy sauce) show higher levels of bioavailable aglycone isoflavones compared to raw or cooked soy foods. [ 14–17 ] Further microbiome‐derived bioactivation of primary metabolites in some individuals is possible in the gut prior to absorption across the gut barrier, producing additional estrogenic molecules. [ 13 ]…”