• Korean Journal of Food Science and Technology
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• v.21 no.4
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• pp.486-491
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• 1989

The textural properties of cooked rice and the molecular weight distribution of amyloses of three rice cultivars different in cooking quality were investigated by the method involving rheometry and gel chromatography he tested rice cultivals were Chunmabyeo (short grain), Yongmunbyeo (medium grain) and Mahatma (long grain) The cooked rice prepared with Mahatma was higher in hardness and lower in adhesiveness than those prepared with the other two cultivars. The molecular wright distribution of amylose from Mahatma was found to be higher than those from the other cultivars.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.1017-1027
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• 1995

This study was attempted to investigate physicochemical properties, molecular structural properties of native and acid-treated chestnut starch and chestnut starch gel. The amylose content was 18.9% and X-ray diffraction pattern showed Cb type. Swelling power was increased abruptly in the range of $65^{\circ}C{\sim}75^{\circ}C$ but increased slowly after that and solubility was increased abruptly until $70^{\circ}C$ but increased slowly after that. In amylograms which have different heating temperatures, cooling viscosity at $50^{\circ}C$ was reduced as heating temperature was increased. In molecular structural properties of amylose, ${\lambda}_{max}$ was 640 nm, ${\beta}-amylolysis$ limit was 84.2% and the degree of polymerization was 951 and in those of amylopectin, ${\lambda}_{max}$ was 570 nm, ${\beta}-amylolysis$ limit was 58.2%, the degree of polymerization was 1371 and average chain length was 22.6. In gel chromatography elution profiles of starch and amylose, 4.0% and 11.5% of low molecular weight-molecules($<5{\times}10^5$) were leached out. In gel chromatography elution profiles of soluble starch, the higher heating temperature was, the more high molecular weight-starches were leached out. The elution profiles after debranching amylopectin with pullulanase showed 2.2 of the ratio of peakIII(DP 10-15) to peakII(DP 35-45). Acid hydrolysis extent of 2.2 N HCI-treated starch at $35^{\circ}C$ for 10 days was 96% and hydrolysis rate showed two step pattern which had border line at 4 days. In elution profiles of acid treated chestnut starch, amylopectin peak was disappeared compeletly after 6 hrs and converted short chains of DP 10-15. Amylose content was increased until 6 hrs but decreased after that. Hardness of starch gel made at $75^{\circ}C$ of heating temperature and cohesiveness of starch gel made at $85^{\circ}C$ of heating temperature were the highest. Retrogradation rate of starch gels were relatively high, especially for the starch gel made at $75^{\circ}C$ of heating temperature.

• Korean Journal of Food Science and Technology
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• v.22 no.6
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• pp.603-610
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• 1990

The structural properties of cold water extractable ${\alpha}-D-glucan$ in rice flours obtained by various milling methods were investigated. The blue value, ${\lambda}_{max}$ values of the iodine complex and ${\beta}-amylolysis$ limit of the cold water extractable ${\alpha}-D-glucan$ were in the range of $0.026{\sim}0.030,\;518{\sim}522\;nm$ and $52.7{\sim}59.6%$, respectively, indicating these materials were composed mainly of amylopectin-like polymer. The gel chromatography on Sepharose CL-2B indicated that the cold water extractable ${\alpha}-D-glucan$ had lower molecular weight but wider molecular weight distribution than that of the original rice amylopectin. The Sephadex G-50 gel chromatography showed that the unit chain distribution of cold water extratable ${\alpha}-D-glucan$ after debranching with pullulanase was similar to that of rice amylopectin. And the ion chromatography of the distribution pattern of the chain length below D.P.30 in the debranched ${\alpha}-D-glucan$ indicated only blade-milled flour was similar to the amylopectin, but in the amount of unit chain below D.P.10, all the ${\alpha}-D-glucan$ in rice flours was higher than that of amylopectin.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.97-102
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• 1998

Arrowroot starches, harvested in March, June, September and December, indicated that the December starch had the lower values of amylose content, ${\beta}-amylolysis$ limit and intrinsic viscosity, but the highest value of water-binding capacity. The swelling power were similar among different starches. The gelatinization by KSCN revealed that the December starch was the most resistant to alkali gelatinization. Gelatinization temperature, determined by differential scanning calorimetry, of the December sample was shifted to higher temperture by $1^{\circ}C$ compared with the others. When the December starch was heated at $98^{\circ}C$ for 8min, 93.8% of total amylose and 7.2% of total amylopectin were solubilized, which was the highest and the lowest, respectively.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.521-527
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• 1996

Some structural characteristics of kidney bean starches (3 varieties : Pink kidney bean, Red kidney bean and White kidney bean) were investigated. The amylose content and the ${\beta}$-amylolysis limit of kidney bean starches were $32.6{\sim}34.5%$ and $69.9{\sim}71.0%$, respectively. The kidney bean amylopectin was composed of super long chain of ${\overline{DP}}$ above 60 ($5.28{\sim}12.62%$), B chain of ${\overline{DP}}$ $45{\sim}60\;(29.85{\sim}33.65%)$ and A chain of ${\overline{DP}}\;10{\sim}20(22.94{\sim}29.85%).$ The chain distribution of kidney bean starches were different from variety to variety. The acid (2.2 NHCI) hydrolysis of kidney bean starches showed, as hydrolysis time increased, the patterns of three stages. The acid hydrolysis rate and iodine reaction of acid treated starches were different from variety to variety As acid hydrolysis time increased, the amylose and the ${\alpha}$-1.6-glucosidic linkage of amylopectin of amorphous state were gradually hydrolyzed. Finally, the chain of ${\overline{DP}}$ 20 of crystalline state was left in the acid treated starches.

• Applied Biological Chemistry
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• v.39 no.3
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• pp.212-217
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• 1996

Molecular structural Properties of Potato starches from Irish cobbler(mealy Potato), Dejima(waxy or soggy potato) and Shepody were investigated. iodine reaction of Irish cobbler, Sephody and Dejima starches were 0.45, 0.44 and 0.43. ${\beta}-amylolysis$ limit of the starches was not different between the three potato types. The percentage of each fraction was different among samples : in general, Dejima starch had higher proportion of $F1(more\;than\;{\overline}{DP})$, $F2({\overline}{DP}40{\sim}50)$ and lower proportion of $F3({\overline}{DP}15{\sim}20)$ than those of Irish cobbler starch. When the starch was heated in excess water at $98^{\circ}C$ for 8min, the yield of hot water-soluble starch were higher in waxy type than in mealy one. Each potato variety showed different gel chromatography pattern of the hot water soluble starch. When the potato starches were hydrolyzed with 2.2N HCI at $37^{\circ}C$ for 48 hr, the molecular weight of the starch was decreased.

• Korean Journal of Food Science and Technology
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• v.23 no.5
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• pp.554-560
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• 1991

The physicochemical properties of Korean yam starches (D. aimadoimo, D. batatas and D. japonica) were investigated. The mean granular size of starches were 23.5 μm for D. aimadoimo, 23.9 μm for D. batatas and 18.2 μm for D. japonica. Amylose content, blue value and water binding capacity was $29{\sim}33%,\;0.42{\sim}0.51%\;and\;109.9{\sim}118.3%$, respectively. The optical transmittance of 0.3% (dry basis) yam starch suspensions were increased at $70{\sim}75^{\circ}C$ and D. japonica showed typical two-step transmittance curve. The swelling power and solubility patterns increased over $60^{\circ}C$, and D. aimadoimo was the highest values. Amylogram patterns of 5% (dry basis) yam starch suspensions, determined by Brabender amylograph, were similar to that of yam flours and the viscosity of D. aimadoimo had 630 BU, which was about 5 times higher than 130 BU for D. batatas and D. japonica. Observation under scanning electron microscope lefted marks of resistance to glucoamylase because these surfaces were similar to the natural granules. In rates of solubiliazation by dimethyl sulfoxide, D. aimadoimo showed the highest value. (3-Amylolysis limits of yam starches and their amylose were $71.8%{\sim}75.5%\;and\;90.2{\sim}92.1%$, respectively. Gel filtration patterns of debranched amylopectin by pullulanase were divided into 3 peaks. The weight ratios of peak III to peak II in yam starches were $2.15%{\sim}2.42%$.