Abstract
Soymilk contains various functional components, such as isoflavones, in addition to vegetable protein. In this study, we attempted to prepare cheese-like foods using soymilk, followed by sensory testing, antioxidant evaluation and isoflavone analyses of the products. First, soymilk was fermented using 11 strains of lactic acid bacteria. Isoflavone glucosides (daidzin and genistin) in soymilk were converted to their corresponding aglycone forms (daidzein and genistein) by Lactobacillus plantarum and Lactobacillus casei fermentation. Lactic acid-fermented soymilk using Lactobacillus casei MAFF 401404, which scored highly in sensory evaluation, was used for the preparation of curd. The curd was individually fermented with two kinds of cheese mold (Penicillium camemberti NBRC 32215 and Penicillium roqueforti NBRC 4622). During the 14-day fermentation/ripening period, a 10- and 11-fold increase of N-formylamino acids was observed in the cheese-like foods. Specifically, glutamic acid (umami taste) was increased and became a major component of these foods. The antioxidant potential of these foods was significantly enhanced (p<0.01) during fermentation/ripening, and exhibited 2- and 3-fold higher activities compared to unfermented curd. Malonylglucoside isoflavones, which were not hydrolyzed by lactic acid bacteria and remained in the curd, were converted by these cheese molds to their aglycone forms, which can be efficiently absorbed into the human body. These results suggest that cheese-like foods produced using soymilk have the potential to be new, acceptable, high value-added foods in the future.
