Qualitative analysis of soy sauces made from fresh okara using two fermentation methods

摘要

Meju, a brick made of fermented soybeans, is the main ingredient of soy sauce. Itwas prepared without (S) or with (OS) 40% okara fermented using Bacillus subtilis(traditional fermentation, TF) or a mixture of Aspergillus oryzae and Aspergillus niger(modified fermentation, MF). MF soy sauces (8.39% and 7.22%) showed a lower salinitythan the TF soy sauce (15.41% and 16.19%), whereas the total nitrogen (TN)in MF soy sauce was twice higher than in the TF soy sauce. Amino-type nitrogen inTF-S (55.0%) was higher than in TF-OS (32.6%), but was lower in MF-S (97.9%) than inMF-OS (113%). The MF soy sauce carried a higher content of total free amino acids(82.7 vs. 85.4 mg/ml) than the TF (23.3 to 50.98 mg/ml). The level of glutamic acidwas the highest in MF-OS (31.2 mg/ml), followed by the levels in MF-S (29.4 mg/ml),TF-S (17.1 mg/ml), and TF-OS (5.9 mg/ml). In sensory test, MF-S (4.26) showed thehighest acceptability, followed by MF-OS (3.65), TF-S (3.22), and TF-OS (3.17). Ourresults revealed that the quality of okara soy sauce can be enhanced when okara mejuwas fermented by Aspergillus rather than Bacillus. The okara fermented by Aspergillusdecreased the fermentation period from 90 to 30 days.