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A metabolomics approach to evaluate post‐fermentation enhancement of daidzein and genistein in a green okara extract
Author(s) -
Gupta Sulagna,
Chen Wei Ning
Publication year - 2021
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.11158
Subject(s) - daidzein , chemistry , isoflavones , fermentation , aglycone , food science , genistein , extraction (chemistry) , genistin , chromatography , daidzin , flavonoid , high performance liquid chromatography , biochemistry , glycoside , organic chemistry , biology , antioxidant , endocrinology
Abstract BACKGROUND Okara is a major agri‐industrial by‐product of the tofu and soymilk industries. Employing food‐wastes as substrates for the green production of natural functional compounds is a recent trend that addresses the dual concepts of sustainable production and a zero‐waste ecosystem. RESULTS Extracts of unfermented okara and okara fermented with Rhizopus oligosporus were obtained using ethanol as extraction solvent, coupled with ultrasound sonication for enhanced extraction. Fermented extracts yielded significantly better results for total phenolic content (TPC) and total flavonoid content (TFC) than unfermented extracts. A qualitative liquid chromatography quadrupole time‐of‐flight mass spectrometry (LC‐QTOF‐MS) analysis revealed a shift from glucoside forms to respective aglycone forms of the detected isoflavones, post‐fermentation. Since the aglycone forms have been associated with numerous health benefits, a quantitative high‐performance liquid chromatography (HPLC) analysis was performed. Fermented okara extracts had daidzein and genistein concentrations of 11.782 ± 0.325 μg mL –1 and 10.125 ± 1.028 μg mL –1 , as opposed to that of 6.7 ± 2.42 μg mL –1 and 4.55 ± 0.316 μg mL –1 in raw okara extracts, respectively. Lastly, the detected isoflavones were mapped to their metabolic pathways, to understand the biochemical reactions triggered during the fermentation process. CONCLUSION Fermented okara may be implemented as a sustainable solution for production of natural bioactive isoflavonoids genistein and daidzein. © 2021 Society of Chemical Industry.