• Korean journal of food and cookery science
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• v.10 no.1
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• pp.76-79
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• 1994

This study was carried out to examine changes in morpholgy and crystallinity of cowpea starch during preparation of chongpo-mook(starch gel food). It was known by photornicroscopy under polarized light and X-ray diffractometry that cowpea starch had lost its crystallinity at the temperature range of 70∼75$^{\circ}C$ It also was obserbed by scanning electron microscopy that overall shape of starch granules was maintained inspite of swelling to considerable extent at the range of 65∼75$^{\circ}C$, however, granules were folded after solubles were extracted out of them above 85$^{\circ}C$. Mechanism of gelation seemed to be formation of junction zones stabilien by groups of weak H-bonds, not by recrystalliztion according to the results of DSC thermogram of reheating of sample pan after cooling and X-ray diffractogram of reheated cowpea starch gel.

• Applied Biological Chemistry
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• v.33 no.2
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• pp.105-108
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• 1990

The numbers of aleurone layers and thickness of pericarp of waxy rice in dorsal side were higher than those in vental side, However, varietal characteristics of the bran structures were observed. The water uptake rates of brown rice at $60^{\circ}C$ were similar between $j{\times}indica$ varieties(Hangangchalbyeo, H and Baegunchalbyeo, B) and higer than that of japonica variety (Shinsunchalbyeo, S). Inherent viscosities for H, B and S waxy rice starches were 1.92, 1.84 and 1.73 $dlg^{-1}$, respectively. The minimum moistures for gelatinization of waxy rice starches determined by DSC were $36.4{\sim}38.6%$ which represented 4moles of water per mole of hexose unit.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.749-753
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• 2002

The effects of green tea powder (GTP) on the rheological properties of dough and gelatinization characteristics were evaluated by farinograph, extensograph, amylograph and DSC. The flours used were high strength flour (HF: 12.5% protein) and blend of 50% high strength flour and 50% low strength flour (HLF: 10.5% protein). As the amount of GTP increased, water absorption, development time and weakness of the dough decreased for both flours, but dough stability increased only for HLF; the extension of the dough decreased but the resistance to extension increased. The pasting temperature increased and maximum viscosity decreased. On the other hand, with the addition of green tea extract to the wheat starch, transition onset temperature, transition peak temper-ature and enthalpy decreased, demonstrating that catechins in green tea facilitate the starch crystal melting.

• Applied Biological Chemistry
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• v.30 no.4
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• pp.315-322
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• 1987

Attempts were made to unravel the differences in the textural properties between a dry type, Wonki and a moist type, Chunmi sweet potato. The changes in the ingredients, cellular shapes, degree of gelatinization and hardness of sweet potatoes during baking were studied. Alcohol insoluble solid, starch and protopectin contents and activities of amylase and polygalacturonase of Wonki sweet potato were higher than those of Chunmi sweet potato. The cell sizes were smaller and the number of starch granules within the cells were higher in Wonki than in Chunmi. Gelatinization occurred in Wonki more lately than in Chunmi during baking. The difference in hardness after baking between Wonki and Chunmi was found distinctively. But both samples were gelatinized completely, the difference in hardness was not found.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.118-124
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• 1998

Dehulled cowpea was microparticulated and coarse fractions and fine fractions were collected by air classification at air classifying wheel speed (ACWS) of 15,000 rpm, 12,000 rpm and 9,000 rpm, respectively. Protein content in fine fraction after air classification was 2 times higher than that of microparticulated cowpea, emulsion capacity was about 3 times than coarse fraction. The coarse fraction of the highest viscosity on the gelatinization properties were detected by amylograph, was C-3 (9,000 rpm coarse)fraction. The majority of microparticulated cowpea particles were oval shaped starch and the rest of them were indeterminate minute particles which had some sharp corners. As an application test, microparticulated cowpea and coarse fraction (C-3) were used for mook (Korea traditional starch jelly) preparation and the wet milled cowpea starch was compared as a control. Some impurities induced discoloring was detected by sensory evaluation but after washing, it made no difference in sensory scores between washed starch and the control cowpea mook. And also syneresis of washed cowpea was less than control. At the above result, it can be to recovery about 85% of cowpea starch using microparticulation/air classification technology.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.508-513
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• 1997

Thermal characteristics and granular morphology on enzyme-resistant starches (RS) formed during heat-moisture treatment (HMT) and retrogradation were investigated in high amylose corn starches, Hylon V and Hylon VII. With each treatment, both starches showed a similar trend in the increase of RS, but RS yield of Hylon VII is higher than that of Hylon V. Specially, RS was increased remarkably by HMT. It was more than doubled from 11.4% to 26.6% for Hylon V and from 15.9% to 32.8% for Hylon VII. A small increase of RS resulted from retrogradation. HMT on starch increased gelatinization temperature, decreased enthalpy. Retrograded starch exhibited small three endothermic transitions at $94^{\circ}C$, $110^{\circ}C$ and $140^{\circ}C$ in differential scanning calorimetry (DSC) thermogram due to the remained ungelatinized starch granules, dissociation of amylose-lipid complex and melting of recrystallized amylose, respectively. Enzyme-resistant starches isolated from native and heat-moisture treated starches showed a broad endothermic transition at higher temperature than native starch, while retrograded starch exhibited a very sharp peak at ${\sim}150^{\circ}C$ due to the melting of amylose crystallites. Under microscopy, starch granules with HMT was not changed, but retrograded starches showed the aggregates of starch granules because amylose leached out during gelatinization. Iodine stained RS clearly showed the differences in enzyme hydrolysis on the native, heat-moisture treated and retrograded starches.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1410-1414
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• 1999

The granular size and shape of durian seed starch were $2.0-10.0\;{\mu}m$ and oval and polygonal. Amylose contents of durian seed, corn, sweet potato and potato starch were 28.3%, 27.5%, 20.3% and 21.7%, respectively. Blue value of durian seed (0.370) higher than that of corn (0.368), sweet potato (0.332), and potato starch (0.338). Alkali numbers of durian seed, corn, sweet potato and potato starch were 7.39, 9.02, 7.08 and 5.43, respectively. Swelling power of durian seed starch was similar to that of sweet potato starch. X-ray diffraction patterns of durian seed starch showed an A-type crystalline structure. According to pasting properties by Rapid Visco-Analyzer, the gelatinization temperature of durian seed starch $(76.6^{circ}C)$ was higher than that of corn $(73.0^{circ}C)$, sweet potato $(72.3^{circ}C)$ and potato starch $(70.2^{circ}C)$. The breakdown of durian seed starch were lower than that of corn, sweet potato and potato starch.

• The Korean Journal of Food And Nutrition
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• v.28 no.1
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• pp.126-133
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• 2015

Ohmic heating uses electric resistance heat which occurs equally and rapidly inside food when the electrical current is transmitted into. Prior to the study, we have researched the potato starch's thermal property changes during ohmic heating. Comparing with conventional heating, the gelatinization temperature and the range of potato starch treated by ohmic heating are increased and narrowed respectively. This result is appeared equally at wheat, corn and sweet potato starch. At this study, we treated potato, wheat, corn and sweet potato starch by ohmic/conventional method and observed change of external structure by microscope and internal structure by X-ray diffractometer. Conventional heated at $55^{\circ}C$ potato starch was not external structural changes. But ohmic heated potato starch is showed largely change. Some small size starch particle were broken or small particles are made of larger particle together or small particles caught up in the large particle. Changes in ohmic heated potato starch at $60^{\circ}C$ was greater. The inner matter came to an external particle burst inside and only the husk has been observed. The same change was observed in the rest of the starch. The change of internal structure of potato starch was measured using X-ray diffraction patterns. There was no significant difference between ohmic and conventional heating at $55^{\circ}C$. But almost every peak has disappeared ohmic at $60^{\circ}C$. Especially $5.4^{\circ}$ peak to represent the type B was completely gone. When viewed from the above results, external changes with change in the internal crystal structure of the starch particles were largely unknown to appear. In conclusion, during ohmic heating changes of starch due to the electric field with a change in temperature by the heating was found to have progressed at the same time.

• Korean Journal of Food Science and Technology
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• v.8 no.1
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• pp.42-46
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• 1976

In order to compare the quality of starches, isolated from the various barley and naked barley species, the gelatinization-temperature and alkali number were determined for 11 species of barley and 13 species of naked barley. The results are as follows; 1. Gelatinizations start at $51-59^{\circ}C$ and complete at $58-64^{\circ}C$ in range. Average gelatinization temperature of the starches from naked barley showed $3^{\circ}C$ lower than those from barley while small differences were observed between species for both barleys. 2. Alkali number varies between 8.0 to 9.5. No significant changes of alkali number were observed between both barleys (8.8 for naked barley and 8.7 for barley in average).

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.5
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• pp.596-602
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• 1993

The Characteristics of Shinsunchalbyeo(Japonica) and Hangangchalbyeo($J{\times}Idica$) starches including physicochemical properties, differential scanning calorimetry(DSC) and enzymatic digestion of lintnerized starches were investigated. Degree of hydrolysis of Hangangchalbyeo starch with 2.2N HCI for 48hr was higher than that of shinsunchalbyeo starch. Absorbance at ${\lambda}_{max}$ 680nm, and ${\lambda}_{max}$ of iodine stained starch decreased upon acid treatment. But water binding capacity, swelling power and solubility considerably increased as hydrolysis progressed. Relative crystallinity of two starches increased with acid treatment, and that of Shinsunchalbyeo starch was higher than that of Hangangchalbyeo starch. DSC data continuously decreased for lintnerization periods, and those of Shinsunchalbyeo starch. DSC data continuously decreased for lintnerization periods, and those of Shinsunchalbyeo starch have higher than those of Hangangchalbyeo starch. The onset temperature of starch by DSC continuously decreased by treatment, but conclusion temperature increased until 24hr and then decreased. The enthalpy for gelatinization decreased for both starches. Degree of hydrolysis of lintnerized Shinsunchalbyeo starch with glucoamylase was slightly higher than that of Hangangchalbyeo starch.