• Applied Biological Chemistry
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• v.42 no.2
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• pp.91-98
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• 1999

To select the desirable soybean cultivar for chonggugjang processing, the physicochemical characteristics of raw soybean materials and chonggugjang samples were investigated. Eight soybean varieties including Danyeobkong, Danbaegkong, Kwanankong, Pureunkong, Manlikong, Sinpaldalkong 2, Jinpeumkong and Hwankeumkong were used for experiment. On the basis of quality characteristics of raw materials, such as seed coat weight rate, hydration swelling, and the content of fructose, glucose and sucrose, and chonggugjang, such as hardness, ${\gamma}-glutamyltranspeptidase\;({\gamma}-GTP)$ activity, free amino acid content, and amino type nitrogen content, Sinpaldakong 2 and Danyeobkong were desirable soybean cultivars for high quality chonggugjang processing.

• Applied Biological Chemistry
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• v.42 no.2
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• pp.111-115
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• 1999

This study was attempted to develop technique of masking the pungent odor of chonggugjang using two-stage fermentation method with mixed pure cultures. Cooked soybeans were fermented with Lactobacilli or Aspergillus oryzae at $38^{\circ}C$ for 36 hrs, and then re-fermented with Bacillus subtilis for 12 hrs. The volatile compounds of chonggugjang were obtained with a SDE(Simultaneous steam Distillation and solvent Extraction) system and the extracts were identified by GC and GC-MS. The experimental results revealed the presence of 35 volatile compounds in control chonggugjang(only Bacillus subtilis inoculation). Among them, the major volatile compounds were 2,5-dimethyl pyrazine, 2,3,5-trimethyl pyrazine and 2-methyl pyrazine. Twenty-nine kinds of volatile compounds were in chonggugjang prepared by two-stage fermentation method with Lactobacilli and Bacillus subtilis(II), and major volatile compounds were identified to be 2,3,5-trimethyl pyrazine and 2,5-dimethyl Pyrazine. In chonggugjang(Asp. oryzae and then Bacillus subtilis inoculation(III)), the contents of hexadecanoic acid and 2-methyl pyrazine were patricularly high and the main components of chonggugjang fermented with rice straw(IV) were 2,5-dimethyl pyrazine, 2,3,5-trimethyl pyrazine etc. In conclusion, the flavor compounds such as 2, 5-dimethyl pyrazine, 2,3,5-trimethyl pyrazine and 2-methyl pyrazine were increased by the inoculation of Lactobacilli or Asp. oryzae, where as unpleasant odor components-butyric acid and valeric acid were decreased. Compared with volatile compounds of chonggugjang made from different soybean cultivars, the flavor compounds (2-methyl pyrazine 2,5-dimethyl pyrazine 2,6-dimethyl pyrazine 2,3-dimethyl pyrazine 2-acetyl pyrazine 2,3,5-trimethyl pyrazine 2-ethyl-3,5-dimethyl pyrazine) of chonggugiang prepared with Sinpaldalkong were high.

• Applied Biological Chemistry
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• v.41 no.5
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• pp.377-383
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• 1998

This study was undertaken to obtain the fundamental data for improving the quality of Korean traditional chonggugjang. To compare the physicochemical properties of traditional chonggugjang produced in different regions, sixty-seven chonggugjang samples collected at nine provinces were analyzed. The average moisture, protein, fat, non-fibrous carbohydrate, fiber, ash, amino nitrogen contents and pH value of collected chonggugjang samples were 55.0%, 17.6%, 3.3%, 13.3%, 4.9%, 5.8%, 0.23%, and 7.21, respectively. The average fatty acid compositions of chonggugjang were 53.8% for linoleic, 21.1% for oleic, 12.4% for palmitic, 9.0% for linolenic, and 3.7% for stearic acid. Traditional chonggugjang contained large amounts of glutamic acid, aspartic acid, and leucine, but less than 0.2% of cysteine and methionine. The average free sugar content was 3.3%, and the dominant free sugar among them were sucrose and galactose. The total average organic acid content of the samples analyzed was 883.0 mg% and citric, acetic, latic, malonic, succinic, formic, tartaric acid were also detected. The Hunter's color L, a, and b values of samples were 49.1, 7, 2, and hardness was $8.3\;kg/{\Phi}20\;mm$.