Douchi is a traditional soybean dish that has been salt-fermented. It has a number of bioactivities, including those that are anti-oxidant, anti-diabetic, and anti-hypertensive. protease and -glucosidase are used in the making of koji. Ideal are edible mushroom byproducts .Due to their distinct nutritional properties, additives can improve the flavour and nutritional value of food high protein, abundant amino acid content, and low calorie properties. There is, however, no study on preparing douchi using a combination of fermentation of edible mushroom byproducts and soybeans. Using protease and glucosidase activities as indicators, the fermentation conditions of the Edible Mushroom by-product Douchi Koji (EMDK) were optimised in this study using response surface methodology (RSM). Unfermented Raw Samples (URS), Douchi koji Without Edible Mushroom by-product (DKWE), and EMDK were then compared for changes in the main bioactive compounds and antioxidant activities. Aspergillus oryzae to Mucor racemosus ratio inoculation amount, edible mushroom amount, and fermentation time of were the best conditions for EMDK fermentation, according to the results of single-factor tests and RSM. The activities of protease and -glucosidase under these conditions, respectively. In addition, EMDK's total isoflavone and -glucoside isoflavone contents were noticeably lower than those of URS and DKWE, although its amino nitrogen, total phenolics, total flavonoids, and aglycone isoflavone levels, as well as its antioxidant capacity, were noticeably higher. Significant relationships between the aforementioned elements and antioxidant capability were also discovered. These findings demonstrated the possibility of cofermenting soybeans with an edible mushroom byproduct, increasing the nutritional content and antioxidant potential of Douchi koji
