Equol, a daidzein metabolite produced exclusively by intestinal bacteria in some, but not all, humans, exhibits a wide range of beneficial health effects owing to its superior nutraceutical effect compared with isoflavones of soy. The aim of this work was to develop bioprocesses capable of increasing the bioactive properties of soymilk and, most importantly, increase the equol content by a biotechnological process in vitro. Biotransformation processes based on soymilk fermentation by probiotic lactic bacteria and application of the enzyme tannase caused an increase in the bioactive isoflavones and antioxidant capacity of soymilk. Furthermore, these processes approximately resulted in a 10-fold increase in the equol content of the soymilk. This is the first study to produce a significant equol concentration in soymilk using enzymatic processing only. The results suggest a new and effective biotechnological process, with major commercial potential, capable of producing a bioactive soy extract that intends to be "functional for everyone."
Keywords: antioxidant capacity; biotransformation; equol; isoflavones; tannase.