An ecofriendly procedure to extract isoflavones from soybean seeds

A novel procedure for isoflavones extraction from soybean seeds using the “green solvent” water was set-up for its future industrial up-scaling. The optimized processing flow-scheme proposed here consists of a 1:5 flour weight-to-water volume ratio mixed by vertical stirrers for 6 min. at 40 °C, with a final 12000-rpm centrifugation, and subsequent lyophilization to ensure stability and easy dosage of the extracts. Results showed that preliminary UV-C light flour irradiation for at least 1 h can improve isoflavones extraction and reduce anti-nutritional factors. Principal component analysis (PCA) and discriminant factorial analysis (DFA) highlighted specific operational conditions, such as extraction volume and time, UV time exposure, and centrifugation speed, for preferential extraction of specific isoflavones. The extraction efficiency varied according to variety choice within a range of 40-73%, possibly due to the relative abundance of the most water-soluble malonyl forms of isoflavones. As the extracts showed promising high stability under freezing and lyophilization conditions, it is concluded that, this ecofriendly extraction approach with can be successfully scalable, helping to save time and energy and obviating at disposal problems in the soy nutraceutical chain.