• Journal of the East Asian Society of Dietary Life
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• v.7 no.3
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• pp.301-307
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• 1997

To enhance the utility value of citron, vinegars were made of citron juice, their properities were investigated, the results are as following. Optimum bacteria was Acetobacter sp. PA 97 for the citron vinegar fermentation, optimum temperature, initial acidity and alcohol concentration were 3$0^{\circ}C$, 1.5% and 8%, respectively. The lower citron juice was added, the more citric acid was produced, the acidity of sample added sub-nutrition source was higher than that of sample no added. In samples added citron juice of 10, 20 and 30%, and sub-nutrition source, total acidity were 5.42, 5.36 and 5.04%, pure acetic acid yields were 52.69, 45.25 and 35.10%, respectively. Remained alcohol of sample no added sub-nutrition source was more than that of added. In the sensory test, the most suitable concentration of citron juice for vinegar fermentation was 30%.

• Applied Biological Chemistry
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• v.38 no.3
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• pp.191-195
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• 1995

Production of a high viscosity exoploysaccharide, methylan, by Methylobacterium organophilum from methanol was carried out in fed-batch cultures and the rheological properties of methylan fermentation broth were studied. Bacterial biomass showed little influence on viscosity, but the accumulation of methylan caused the increase of viscosity. With proceeding fermention, the viscosity at the same concentration of methylan was significantly increased and methylan solution showed slightly higher pseudoplasticity. The composition changes of methylan were investigated at various fermentation times. Contents of total sugar, reducing sugar and methylan were decreased but contents of acids(pyruvic acid, uronic acid and acetic acid) were increased with the culture time. It was considered that the increased content of acids resulted in the increase of the hyrodynamic domain in the solution due to charge repulsion. Consequently, the solution viscosity increased in propotion to the acids contents of methylan. Cell growth and methylan production were severely decreased by the limitation of dissolved oxygen. However, the cellular activity for methylan production was almost constant regardless of the level of dissolved oxygen. As a result, the high speed of agitation increased the methylan production, the specific production rate of methylan, and the methylan yield of the cell.