This study was conducted to establish the brewing method which would be useful for the production of Kochuzang. Kojis, which were made from various materials and microorganisms under a covered condition, were investigated and compared. Yeasts (Saccharomyces rouxii and Torulopsis versatilis) were added to Kochuzang, and the enzyme activity, microflora, chemical composition, nitrogen content, alcohol content and free sugars of Kochuzang were investigated and analysed. The results obtained are as follows:
1. Koji making
(1) Glutinous rice-soybean group was superior to glutinous rice group in the saccharogenic and liquefying amylase activities of three day-Koji.
(2) Protease activity (acid, neutral and alkaline) of glutinous rice-soybean Koji, which was inoculated with Aspergillzus oryzae A, was increased till the 5th day, while other groups showed maximum activity after the 3rd day.
(3) The maximum cellulose activity of Aspergillus oryzae B-Koji and A-Koji was observed after the 2nd day and the 3rd day, respectively. High cellulose activity of Aspergillus oryzae B-Koji and A-Koji was respectively shown in glutinous rice group and glutinous rice-soybean group at maximum.
(4) Compared with glutinous rice Koji, Mutinous rice-soybean Koji gave larger number of yeast and aerobic bacteria.
2. Kochuzang Fermentation
(1) Each Kochuzang group shoved different liquefying and saccharogenic amylase activities.
The highest activities were generally shown in 10 to 40 days after mashing and remarkably reduced in the last stage of aging.
(2) Protease activities of each group were strong in order of acid, neutral and alkaline protease. Especially acid protease showed highest activity at the 40th to 50th day Kochuzang
(3) Each group showed maximum cellulase activity in the 40th and 50th day-Kochuzang and then decreased.
(4) Osmophilic yeast of yeast-added Kochuzang after one-month aging was distinctively outnumbered compared with non-yeast-added Kochuzang, but two groups were similar after two months.
(5) Yeast-added group and non-added group gave almost the same number of halophilic lactic acid bacteria in Kochuzang, but the non-added group gave slightly larger number of aerobic bacteria than the yeast-added group.
(6) Amino nitrogen cements in all test group were increased rapidly till the 60th day of Kochuzang aged. After that the contents were increased slowly.
(7) Ethyl alcohol contents of 20day-fermented Kochuzang were high in order of Saccharomyces rouxii-added group, Torulopsis versatilis-added group, Saccharomyces rouxii and Torulopsis versatilis mixed group and non-yeast-added group. But all test group showed about 2% in ethyl alcohol content after 40days of aging.
(8) Alcohol content in the 7 month-aged Kochtszattg of all test groups was high in order of ethyl alcohol, n-butyl alcohol, n-propyl alcohol and iso-propyl alcohol. Torulopsis versatilis-added group had the highest value of ethyl alcohol, n-propyl alcohol and n-butyl alcohol.
(9) Reducing sugar in Kochuzang was increased after 20 days cf aging compared with the 10 days-ferment. The reducing sugar content in Saccharomyces rouxii-added group was distinctively small compared with that of other groups, decreasing after 30days of aging.
(10) Rhamnose, fructose, glucose and maltose were isolated from the 10 day fermented Kochuzang. Raffinose was also found after 300 days-aged group, and fructose content was high in the 300days-aged Kochuzang. However, glucose content was smaller than that of 10days-fermented Kochuzang.
(11) For the organoleptic tests of Kochuzang, taste, flavour and color of yeast-added group were superior to the non yeast-added group. Especially the complex yeast group among the yeast added groups were the best of all. Yeast-added group after 300 days of aging took higher paint in flavour test than that of non-added group. Therefore, brewing method like complex yeast added group seems to be advantageous for short time brewing Kochuzang.
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