Improvement of nutritional quality and antioxidant activities of yeast fermented soybean curd residue
This study evaluated the potential use and improves the health beneficial properties of the waste of soybean manufacturing products by solid-state fermentation of six GRAS different yeast strains, including extractable antioxidant activities and bioavailable nutritional compositions. In comparison with non-fermented okara (control), some levels of value addition occurred as a result of the fermentation. The protein contents increased by 20.10- 54.40%, while the crude fibre decreased by 7.38- 45.50% with different strains. With all the organisms used, the ash content increased while the carbohydrate and lipid contents were reduced. Total phenolic content and all parameters of antioxidative activities were increased in fermented substrate. The highest significant levels of antioxidant activities were achieved with Kluyveromyces marxianus NRRL Y-8281. Results showed that the nutritional quality and antioxidant activities of the substrate were enhanced by solid yeast treatment fermentation. Thus, scope exists for microbial upgrading of this low-quality waste and development of healthy animal feed supplements.
Key words: Solid state fermentation, yeast, waste soybean manufacturing products, antioxidant, protein, fiber.