• Food Science and Preservation
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• v.21 no.2
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• pp.286-293
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• 2014

In this study, one GRAS strain was screened from doenjang, a traditional Korean fermented food, as a microorganism producing amylase due to the formation of a clear zone on the medium including soluble starch. From the analysis of the gene sequence of 16S ribosomal RNA, the strain was identified as Bacillus subtilis and was therefore named Bacillus subtilis CBD2. When the nutrient broth medium was prepared with 3% NaCl, 5% glucose, and the initial medium pH 7.0, the B. subtilis CBD2 showed maximum growth. Among soluble starch, corn starch, maize amylopectin, and wheat starch, soluble starch was the most effective carbon source in the production of amylase by B. subtilis CBD2. The amylase from B. subtilis CBD2 showed the highest activities at pH 8.0 and $50^{\circ}C$, and corn starch was the most proper substrate for the enzyme activity. When corn starch was used as a substrate, the production of sugars through enzyme activity increased for 24 h, and then the enzyme activity became constant.

• Food Science and Preservation
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• v.22 no.2
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• pp.225-231
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• 2015

This study was conducted to examine the physicochemical properties and micro-encapsulation process of rice fermented with Bacillus subtilis CBD2. The viable bacterial cell, pH, and amylase activity of the rice liquid culture were 7.61 log CFU/mL, pH 5.08 and 159.43 units/mL, respectively. The micro-encapsulated rice liquid culture was manufactured via spray drying with different forming agents: i.e., alginic acid 1.0% and chitosan 0.3%, 0.5%, and 1.0%. The moisture contents of the spray-dried powders were approximately 2.90~3.68%. The color of the L and a value decreased whereas that of the b and ${\Delta}E$ value increased. The particle size and outer topology of the spray-dried rice liquid culture were $48.13{\sim}68.48{\mu}m$ and globular, respectively. The water absorption index of the spray-dried powder (2.40~2.65) was lower than that of the freeze-dried powder (2.66). The water solubility index of the spray-dried powder (9.17~10.89%) was higher than that of the freeze-dried powder (7.12%). The in vitro dissolution was measured for five hours in pH 1.2 simulated gastric fluid, and pH 6.8 and pH 7.4 simulated intestinal fluids, using a dissolution tester at $37^{\circ}C$ with 50 rpm agitation. The amylase survival in the fermented rice was 85.93% through the spray-drying and it was very effectively controlled.