• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.72-72
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• 2003

A 10-week feeding trial was conducted to investigate the effects of dietary glucose, dextrin and starch on growth and body composition of juvenile starry flounder. Triplicate groups of fish (average weight, 9.7 g) were fed iso-nitrogenous (53% CP) and iso-caloric (3.8 kcal/g diet) diets containing 20% glucose, 20% dextrin and 5-25% alpha-potato starch with 5-14% lipid levels. Survival was not affected by dietary carbohydrate. Weight gain, feed efficiency and protein efficiency ratio of fish fed the diet containing 20% glucose were the lowest among all groups. The best weight gain was observed in fish fed the diets containing 20% dextrin. Growth and feed efficiency were not affected by dietary -potato starch level. Lipid contents of whole body and liver were not affected by dietary glucose, dextrin and starch at the same level. However, the lipid contents tended to decrease with increasing dietary starch level and those of fish fed the diets containing 5% alpha-potato starch were significantly higher than those receiving 10-25% alpha-potato starch. Liver glycogen content and hepatosomatic index tended to increase with increasing dietary starch level. These results indicate that juvenile starry flounder are able to efficiently utilize dextrin and -potato starch compare to glucose in diets and that alpha-potato starch could be incorporated up to 25% in the diet for optimum growth by juvenile starry flounder.

• KSBB Journal
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• v.11 no.1
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• pp.86-91
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• 1996

Optimal reaction condition for the starch hydrolysis by ${\alpha}$-amylase was determined and the sugar produced under the optimal condition was measured for estimating the biodegradation of strach-filled polyethylene film. Optimal ranges of temperature and pH were 70~$80^{\circ}C$ and 6.3~7.3, respectively. The 100 units of ${\alpha}$-amylase per mg starch were enough for the enzyme reaction. Reaction with polyethylene film containing 5%, 10%, 15% and 20% starch in the above condition showed that the sugar produced was proportional to the starch content in film. This relationship provides a calibration curve for determining the starch content of search-filled polyethylene film. The average amount of hydrolyzed starch was about 40% of total starch in film. The rest of the starch is considered to be still dispersed in the film and not to be attacked by ${\alpha}$-amylase. In this experiment, we could obtain the higher biodegradability through the $\alpha$-amylase reaction in the above optimal condition than the reported one which had been Improved by adding surfactant.

• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.876-881
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• 1997

The relationship between the molecular structure of acid-hydrolyzed rice starch and the retrogradation rate of starch gel was investigated. The molecular structure of starch was modified by acid hydrolysis with 1 N HCl at $35^{\circ}C$. The molecular weight of starch decreased as acid hydrolysis time was increased. At the early stage of hydrolysis up to 3 hr, the branching point of amylopectin was degraded and thereafter both ${\alpha}-1,4\;and\;{\alpha}-1,6$ linkages were hydrolyzed. The starch gel (50%) stored at $20^{\circ}C$ revealed that the rapid retrogradation occurred during 4 hr of storage which was more pronounced as the hydrolysis time increased. The degree of retrogradation of starch gels after 4 hr storage showed a linear relationship with the yield of hydrolyzate. These results suggested that the retrogradation of starch gel was accelerated by degradation of ${\alpha}-1,6$ linkages with acid.

• Journal of Aquaculture
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• v.11 no.2
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• pp.133-140
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• 1998

A 20-week growth trial was conducted in flow-through aquarum system to investigate the practical dietary carbohydrate sources for juvenile abalone (Haliotis discus hannai). Four replicate grops of the abalone averaging 0.125g were fed one of eight diets containing 24.2% wheat flour (WF), 20% dextrin (DEX), 20% sucorse (SUC), 10% $^{\alpha}$-potato starch+10% $^{\beta}$-potato starch (ab-S), 15% $^{\alpha}$-potato starch (a-S15), 20% $^{\alpha}$-potato starch (a-S20), 25% $^{\alpha}$-potato starch (a-S25), or mixture (MIX) with practical ingredients such as soybean meal, corn gluten meal, cotton seed meal and heat flour. In addition, these formulated diets were compare with macroalgae such as dried sea mustard Undaria (D-SM) or dried sea tangle Laminaria(D-ST). Survival rate, weight gain, shell growth and soft body weight of abalone were not significantly affected by the different dietary carbohydrate sources (P>0.05), whereas those fed a-S15 diet were slightly low. These values of abalone fed D-ST were lowest (P<0.05), followed by those fed D-SM. Lipid contents of soft body from abalones fed a-S25, D-ST or D-SM were significantly lower than those of abalone fed other diets (P<0.05). These data indicate that abalone can equally utilize any carbohydrate sources used in this study.

• Journal of Microbiology and Biotechnology
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• v.4 no.3
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• pp.230-232
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• 1994

The enzymes $\alpha$-amylase and glucoamylase used in starch hydrolysis were found active in the supercritical carbon dioxide solvent Higher hydrolysis of starch sluny in supercritical $CO_2$ was achieved by operating the reactor for the first two hours with $\alpha$ -amylase and to subsequent addition of glucoamylase for continued hydrolysis.

• Microbiology and Biotechnology Letters
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• v.18 no.4
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• pp.352-359
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• 1990

The synergistic effect of glucoamylase and a -amylase on the hydrolysis of raw corn starch in an agitated bead reaction system was studied by investigating the changes of sugar profiles, the granular structure, particle size distribution, and X-ray diffraction pattern of residual raw corn starch. The enzymatic hydrolysis of raw corn starch was greatly enhanced by synergistic effect of glucoamylase and $\alpha$ -amylase. Even though the sugar profiles were mainly determined by the mixing ratio of glucoamylase and $\alpha$-amylase; raw starch was mainly converted to glucose directly without accumulation of any significant amount of oligosaccharides. The cavity formation and fragmentation phenomena of raw corn starch granule subjected to enzyme reaction were analyzed by means of SEM and the particle size distribution. The X-ray diffraction pattern of raw starch was not changed at the initial stage of reaction but slightly changed at the late stage of hydrolysis, which may be caused by the preferential degradation of amorphous region by enzymatic reaction, not by the destruction of microcrystalline structure of raw corn starch.

• Microbiology and Biotechnology Letters
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• v.26 no.2
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• pp.187-194
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• 1998

Glycosides were synthesized using transglycosylation reaction of amylase in water system. Starch as a glycosyl donor and benzylalcohol as an acceptor were selected as substrates of transglycosylation reaction. Among tested 9 commercial amylase, amyloglucosidase from Rhizopus sp. had high activity for transglycosylation from starch. The glycoside synthesized in water phase by amyloglucosidase was identified as benzylalcohol-${alpha}$-glucoside (BG) of which one molecule of benzylalcohol was bound to 1-OH of glucose. The transglycosylation reaction by amyloglucosidase were carried out in reaction system containing 50 mg starch, 50 mg benzylalcohol, and 10 units enzyme in pH 5.0 at 45$^{\circ}C$. The synthesized BG was hydrolyzed by ${alpha}$-glucosidase to produce glucose and benzylalcohol.

• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.190-195
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• 1992

In the polyethylene glycol/dextran aqueous two-phase systems, volume ratio was increased and partition coefficient was decreased with the increase of potyethylene glycol molecular weight and concentration. However the volume ratio was decreased and the partition coefficient was increased with the increase of dextran molecular weight. On the other hand, the volume ratio and the partition coefficient were decreased with the increase of dextran concentration. Continuous enzymatic hydrolysis of soluble starch with $\alpha$-amylase which was produced by Bacillus amyloliquefaciens IF0 14141 was investigated in polyethylene glycol/dextran aqueous two-phase systems. Nonreacted soluble starch and $\alpha$-amylase were reused in these systems. $\alpha$-Amylase activity was maintained more than 100 hrs by recycling of $\alpha$-amylase from bottom of settler to reactor.

• Microbiology and Biotechnology Letters
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• v.18 no.3
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• pp.260-267
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• 1990

The mechanism of enzymatic hydrolysis of raw corn starch by the purified glucoamylase and a - amylase in an agitated bead reaction system was studied by investigating the changes of sugar profiles produced by each enzyme, the granular structure of raw corn starch, the amount of enzyme adsorption on residual starch, and the amylose content in residual raw starch. The sugar profiles produced by the action of exo-type glucoamylase or endo-type $\alpha$ -amylase in an agitated bead system were not recognizably differed with those produced in reaction system without bead. Without enzyme the intergenic microcrystalline structure of starch granule was not changed by the simple mechanical impact of solid media, but it was cleaved. However, starch granule was fragment into large number of small particles by the synergistic action of enzyme and attrition-milling media, identified to be the major saccharification enhancing mechanism along with the increased amount of enzyme adsorption. The amylose content decreased more readily in an agitated bead reaction system, especially by $\alpha$ -amylase.

• The Korean Journal of Food And Nutrition
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• v.12 no.3
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• pp.265-270
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• 1999

The stabilization of Aspergillus sp. $\alpha$-amylase was attained by modification with periodate-oxidized sol-uble starch. The pH stability of modified enzyme was increased at pH 3~4 and 9~11 in the presence of $\alpha$-cyclodextrin($\alpha$-CD) compared with that of native enzyme. Thermal stability of the modified enzyme was increased. After treatment at 6$0^{\circ}C$ for 30min the activity remained 20% for the enzyme modified at pH 9.7 in the presence of $\alpha$-CD and tested in the presence of $\alpha$-CD 10% for the enzyme modified at pH 9.7 in the presence of $\alpha$-CD 0% for the native enzyme. The native enzyme and modified enzyme showed one peak in HPLC. The substrate specificity of the modified enzyme was not changed in HPLC analysis of reaction product.