Abstract:

In the present study, a series of single factor experiments were conducted to examine the effects of pretreatment and inoculation conditions on protease and glutamine activities during soy sauce koji processing. This was followed by the investigations on importance order of these conditions and their optimum values using orthogonal array design. The results showed that the importance order of process conditions affecting protease activity was: inoculum size＞fermentation time＞fermentation temperature and the optimum conditions for maximizing protease activity were as follows: inoculum size 0.8%, fermentation temperature 32 ℃ and fermentation time 36 h; and the importance order of process conditions affecting glutamine activity was: fermentation temperature＞fermentation time＞inoculum size and the optimum conditions for maximizing glutamine activity were as follows: noculum size 0.5%, fermentation temperature 28 ℃ and fermentation time 60 h.

Key words: soy sauce koji, protease, glutaminase, Aspergillus oryzae