Chungkook-jang Koji was fermented with rice straw at 40° and 50℃ for 72 hours. The changes of proximate composition, pH, titrable acidity, nitrogen compounds, protease activity and free-amino acids during the fermentation were investigated. Moisture, lipid and protein contents remained essentially unchanged during the fermentation.
The pH was gradually increased from 6.4 to 7.46 and 7.82 at 40° and 50℃, respectively, after 72 hour fermentation. Amino type and water soluble nitrogen increased as fermentation progressed. however, the former slightly decreased after 60 hour fermentation.
Chungkook-jang fermented at 40℃ showed somewhat higher protease activity than 50℃. However, protease activity at both fermentation temperatures showed the same trend; that is, it increased until 48 hour fermentation and thereafter decrease. Free amino acid content of Chung-kook-fang after 72 hour fermentation at 40℃ was 6 times greater than that of the steamed soybean, while it was 2.5 times greater at 50℃. Based on these results. it seems that the optimum fermentation conditions for Chungkook-jang were 40℃ and 72 hours.
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