Modified gluten by extrusion can significantly improve the amounts of flavor compounds during the fermentation of umami condiment

Gluten is widely used in food process, but rarely used in the fermentation of umami condiment. The extrusion treatment could modify the microstructure of gluten, which may further influence fermentation effectiveness. This study applied gluten and modified gluten obtained by extrusion as raw materials to koji and moromi fermentations. During the koji fermentation, water and Aspergillus oryzae applied to modified gluten penetrated into the inner layer of raw material more efficiently when compared with their application to gluten. After the fermentation, the amino acid nitrogen contents of prepared four group samples ranged from 0.80 g/100 mL to 1.05 g/100 mL, while the contents of glutamic acid, adenosine monophosphate (AMP), guanosine monophosphate (GMP), acetic acid and lactic acid etc. had significant increases, indicating the utilization of gluten in fermentation could produce large amounts of flavor compounds. Additionally, the modification of gluten accelerated the fermentation of A. oryzae and improved the utilization and efficiency of fermentation raw materials, while the soybean protein isolate could partially replace gluten to produce high amounts of flavor compounds during the fermentation. This study broadened the utilization scope of gluten in food industry and provided a reference for the fermentation of umami condiment.