• Journal of Microbiology and Biotechnology
• /
• v.2 no.2
• /
• pp.85-91
• /
• 1992

The intestinal microflora of humans is an extraordinarily complex mixture of microorganisms, the majority of which are anaerobic microorganisms. The distribution of amylolytic microorganisms in the human large intestinal tract was investigated in various individuals of differing ages using anaerobic culture techniques. A large percentage of the amylolytic microorganisms present belonged to the Genus Bifidobacteria. The number of Bifidobacteria increased significantly at two years of age. Adults and children above 2 years old carried about $0.8{\times}10^9-2.0{\times}10^{10}$ colony forming units (CFU/gram) of amylolytic Bifidobacteria. Among these amylolytic Bifidobacteria, Int-57 was chosen for further studies. Between 65% and 85% of the amylase produced was secreted and the remaining amylase was bound to the cell wall facing the outside. Amylase production could be induced by starch in a stable form. When cells were grown on maltose or glucose, amylase production was much lower than on starch and amylase activity disappeared after 24 hours growth on these media. Partially purified enzymes showed optimum activity at a temperature of $50^{\circ}C$ and at an optimum pH of 5.5, respectively. Heat treatment at $70^{\circ}C$ for 30 minutes almost completely inactivated amylase. The hydrolysis products of starch were mainly maltose and maltotriose. Soluble starch, amylose, amylopectin, and $\gamma$-cyclodextrin($\gamma$-CD) were easily hydrolyzed. The rate of hydrolysis of $\alpha$-CD and $\beta$-CD was slower than that of $\gamma$-CD. Carboxymethyl cellulose, $\beta$-1, 3-glucan and inulin were not hydrolyzed.

• Microbiology and Biotechnology Letters
• /
• v.29 no.1
• /
• pp.31-36
• /
• 2001

Paenibacillus sp. JB-13 producing the cyclodextrin glucan-otransferase(CGTase) [EC 2.4.1.19] that glucosylated ascorbic acid(AA) at the C-2 position was isolated form soil and the optimal conditions for the production of 2-O-$\alpha$-D- Glucopyranosl L-Ascorbic acid(AA-2G) with CGTase were investigated. CGTase produced AA-2G efficiently using dextrin as a substrate and AA as an aceptor. Several AA-2-oilgosaccharides(AA-2Gs) were also produced in this reaction mixture, and these were efficiently hydro-lyzed to AA-2G and glucose by the treatment with glucoamylase. The optimal temperature for AA-2G production was $37^{\circ}C$ and the optimal pH was around 6.5. CGTase also utilized $\alpha$-,$\beta$-,${\gamma}$-CDs, soluble starch, com statch, dia-static solution from rice and diastatic solution from malt as substrate, but not glucose. The reaction mixture for the maximal production of AA-2G was following; 15% total substrate concentration, 2,500 units/ml of CGTase and a mixing ration of 3:2(g of AA: g of dextrin). Under this condition, 56 mM of AA-2G ,which corresponded to 12.4% yield based on AA. was produced after incubation for 44 hrs at $37^{\circ}C$ and pH 6.5.

• Korean Journal of Food Science and Technology
• /
• v.26 no.3
• /
• pp.336-342
• /
• 1994

Changes in physicochemical characteristics were investigated for immature barley kernels roasted at $160{\sim}220^{\circ}C$ for $1{\sim}12$ min. Only small differences in chemical constituents including starch, protein, fat, ash, total dietary fiber, and ${\beta}-glucan were observed between immature and mature barley kernels. The amounts of 75% ethanol-soluble sugars and amino acids present in immature barley kernels were considerably higher than those in mature kernels, and gradually decreased in the process of roasting. Of free sugars, sucrose, raffinose, glucodifructose($GF_{2}$) and maltose were reduced by roasting. Glucose and fructose, simple reducing sugars, decreased at the early stage of roasting, followed by a slight increase at the later stage. Starch and nitrogen contents decreased slowly, while TDF(total dietary fiber) had a tendency to increase slightly. Stacking volume of immature barley kernels increased markedly, especially at the higher temperatures. L value of immature barley decreased throughout roasting, and a, b values increased at the early stage of roasting but b value decreased with continued roasting. The degree of roasting was strongly affected by the roasting temperature. Darkness of immature barley kernel, depending on the degree of roasting, was highly associated with concentrations of brown pigments extracted from roasted immature barley kernels.