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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Food Quality Laboratory » Research » Publications at this Location » Publication #397675
Research Project: Integrated Approaches to Improve Fruit and Vegetable Nutritional Quality with Improved Phenolics Contents

Location: Food Quality Laboratory

Title: Isoflavone composition of germinated soybeans after freeze-thaw

Author
item JI, WENMIN - Qingdao University
item Yang, Tianbao
item Song, Qijian
item MA, MENG - Qingdao University

Submitted to: Food Research International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2022
Publication Date: 10/27/2022
Citation: Ji, W., Yang, T., Song, Q., Ma, M. 2022. Isoflavone composition of germinated soybeans after freeze-thaw. Food Research International. 16. Article 100493. https://doi.org/10.1016/j.fochx.2022.100493.
DOI: https://doi.org/10.1016/j.fochx.2022.100493

Interpretive Summary: Aglycones, isoflavone monomers without glycosyl group, have a high biological activity after dietary intake. This research reports the effect of freeze-thaw on isoflavone composition in germinated soybeans, particularly the conversion of aglycones. Seed germination promoted the accumulation of total isoflavones in different cultivar soybeans seeds. The germinated soybeans were frozen at -20 °C, -80 °C, and - 196 °C and subsequently thawed at 4 °C, 10 °C, and 25 °C. The freeze-thaw treatments destroyed the cell structure of germinated soybean cotyledons, increased water to penetrate intercellular space and enhance mobile microenvironment, and led to increased aglycones content. Aglycones content increased most at -20 °C, which increased about 24 times. These results indicated that the freeze-thaw method greatly increased the content and profile of isoflavones, and enhanced the conversion to high aglycones. This methodology provides an effective approach for industry to enrich aglycones of germinating soybeans.

Technical Abstract: Soybean is rich of isoflavone. Aglycones are isoflavone monomers with a high biological activity after dietary intake. This research reports the effect of freeze-thaw on isoflavone composition in germinated soybeans, particularly the conversion of aglycones. The germinated soybeans were frozen at -20 °C, -80 °C, and - 196 °C and subsequently thawed at 4 °C, 10 °C, and 25 °C. Results showed total isoflavone increased after germination. Aglycones content increased most at -20 °C, which increased about 24 times. The effect of thaw temperature and time indicated there were approximately 89% glucosides forms converted to aglycones during freeze-thaw. Isoflavone conjugate-hydrolyzing ß-glucosidase (ICHG) activity increased by 65.78% (25 °C) and 59.14% (48 h) with freeze-thaw. The cells of germinated soybeans were broken and T 22 increased after freeze-thaw, which promoted ICHG contact with glucosides and malonyl-glucosides. These results indicated that freeze-thaw greatly changed the content and profile of isoflavones, resulting in a sharp increase in the content of aglycones, and provided an effective approach for industry to enrich aglycones of germinating soybeans.