Soybean meal and fermented soybean meal as functional ingredients for the production of low-carb, high-protein, high-fiber and high isoflavones biscuits

Processing may affect the bioactivity of soy food products, due to the conversion between isoflavones' chemical forms. We investigated the effect of dry-heating or fermentation by Saccharomyces cerevisiae on soybean meal (SBM) chemical composition, with emphasis on isoflavone glycosides to aglycones conversion. Biscuits were prepared with aglycone-rich SBM and evaluated regarding their technological, nutritional, functional and sensory properties. Fermentation yielded more isoflavone aglycones (7.8-fold) than dry-heating (2.5-fold). Fermentation improved nutritional quality (50% increase in fiber, and 32%, 83% and 69% decreases in carbohydrate, lipid and trypsin inhibitors, respectively) and increased antioxidant activity (up to 206%) of SBM. Soybean meal biscuits showed adequate technological properties and improved nutritional and functional qualities in comparison to wheat biscuits (up to 3.7-, 4.6-, 2.8- and 4.7-fold increases in protein, dietary fiber, ash and antioxidant activity, respectively; 2.1-fold decrease in carbohydrate). SBM biscuits showed good sensory acceptance, whereas fermented SBM biscuits showed low sensory scores.