• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.6
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• pp.637-645
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• 1991

Physicochemical factors affecting cooking and eating quality of rice and their mechanisms were investigated. The stickiness of cooked rice was negatively correlated with amylose content(r=0.58, p<0.05) and protein content(r=-0.72, p<0.01), but not affected by crude fat content of rice. The ultrastructure of cooked rice grain showed the progressive gelatinization of starch from the periphery toward the center of the endosperm as water and heat energy diffused into. The rate of water diffusion appears to be dependent on the cell arrangement in the endosperm and the protein content of milled rice. Once water and heat reach the starch granules, the rate of in situ gelatinization of starches appears to be dependent on their own gelatinization temperature range and amylose content. Protein acts as a barrier for the swelling of starch and water diffusion in two ways : 1) by encasing starch granules in the starchy endosperm, and 2) by forming a barrier between the subaleurone layer and the starchy endosperm. Therefore, the separation and fragmentation of the outermost layers of the endosperm occurred more easily in the low-protein content rices, and was associated with increases of solids lost in cooking-water at 95$^{\circ}C$ and stickiness of cooked rice.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1024-1028
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• 1998

Crystalline structure of the extrudate of high amylose corn starch was studied by X-ray diffractometer and $^{13}C\;NMR$. The X-ray diffraction crystal ratio of the extrudates (barrel temperature $100^{\circ}C$ )of high amylose corn starch slightly increased from 6.08% to 8.37% by increasing feed moisture content from 25% to 45%. But extrudates of high amylose corn starch showed similar crystal ratio on various extrusion conditions. Extrudates of high amylose corn starch (feed moisture content 20%, barrel temp $140^{\circ}C$) showed more enlarged crystal structure than that of non-extrudates. The perpendicular distance of crystal increased by extrusion. Crystal ratio was changed from $6.3{\sim}8.3%$ to $4.5{\sim}5.8%$ during storage at $4^{\circ}C$. Starch configuration was examined with $^{13}C\;NMR$. Double helical content was measured by $^{13}C\;NMR$ method. The highest double helical content (60%) was obtained from high amylose corn starch extrudate (barrel temp.: $100^{\circ}C$, feed moisture content 45%). Double helical contents and resistant starch (RS) yield (pancreatin) were positively correlated. However, double helical content of the extrudates was not changed by the storage at $4^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.45 no.5
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• pp.613-618
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• 2013

The quality characteristics of brown rice polished with grains of four rice varieties (Hwaseonchal, Baegjinju, Ilpum and Goami) were examined. For the physical properties of native and fried brown rice starches, the gelatinization temperatures and enthalpies (determined with differential scanning calorimetry) of brown rice starches decreased with increasing amylose content. The pasting viscosities of native brown rice starches in distilled water were higher than those in $HgCl_2$ solution (as an ${\alpha}$-amylase inhibitor). The highest viscosity of gelatinized starch was observed for the starch of Ilpum rice variety relative to other varieties. Cystal packing arrangement of brown rice starches subjected to deep-fat frying converted A-type (typically observed for cereal starches) into V-type (formed by retrogradation and recrystllization of amylose molecules).

• Korean journal of food and cookery science
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• v.13 no.4
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• pp.379-383
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• 1997

To study the effect of amylose on the mechanism of gel formation, swelling power, water solubility, the pattern of alkali gelatinization and gel properties were investigated. The swelling power of waxy maize starch (Amioca) was the highest and followed by those of PFP > Amaizo > Amylomaize VII. Amioca showed higher iodine affinity of soluble amylose than other maize starches. The apparent viscosity of alkali gelatinization measured by Brookfield viscometer for Amaizo was 70${\times}$10$^3$cp which was higher than Amylomaize VII. The apparent viscosity of PFP was increased to 70${\times}$10$^3$cp and then decreased. As maize starches were autoclaved at 121$^{\circ}C$ with starch: water ratio (1 : 9) and autoclaving-cooling cycle were up to 4 times, gel properties were measured by rheometer. Amaizo showed the highest value for hardness, adhesiveness, springiness, and cohesiveness, and hardness of gel after two cycles of autoclaving-cooling was the highest. Gel properties seemed to be affected by the chain length of amylose rather than the content of amylose.

• Journal of the East Asian Society of Dietary Life
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• v.14 no.2
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• pp.145-155
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• 2004

From the cooking data, Japanese rice showed higher water uptake but lower expansion volume, pH and iodine blue value than those of Korean rice. Japanese rice had higher maximum viscosity, breakdown viscosity and pasting temperature but lower final viscosity and setback viscosity than those of Korean rice by RVA analysis. Japanese rice had higher LC (low compression) hardness, U stickiness and HC (high compression) stickiness, LC balance and HC balance, but had lower HC hardness and thickness in the tensipresser data. Also Japanese rice had higher stickiness and balance, and lower hardness from the texturometer analysis. Japanese rice showed higher a cooked taste score than that of the Satake cooked taste machine. The various mean values of Japanese rice after cooking showed better cooking characteristics than the Korean rice. These results might be caused because Japanese rice had a little lower amylose and protein content, but higher tat acidity content.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.886-891
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• 1997

The interrelation between physicochemical properties of milled rice and retrogradation of rice bread during cold storage was examined to compare the varietal difference in maintenance of rice bread quality. Twelve rice materials showed big varietal difference on physicochemical properties of rice starch such as amylose content(0.0~29.2%), gel consistency(20~98mm), and alkali digestion value(2.0~7.0). Rice bread made from milled rice of Jungwonbyeo, AC 27 and IRAT 177 exhibited soft texture and late retrogradation of rice bread during cold storage(4$^{\circ}C$). The amylose content of milled rice was closely associated with gel consistency negatively and with springiness of rice bread positively. The retrogradation of rice bread texture during cold storage was correlated with gel consistency of rice flour positively and with alkali digestion value of milled rice negatively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.6
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• pp.646-652
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• 1991

Factors affecting gelatinization temperature of rice starches from different varieties were investigated. Birefringence end-point temperature(BEPT), amylose content, granule size distribution and degree of crystallinity of rice starches showed the significant varietal differences at ${\alpha}\;=0.01$. Susceptibility of the granule to gelatininzation was dependent mainly on the degree of crystallinity, as indicated by the significant positive correlation between BEPT and the relative crystallinity(r=0.67, p<0.01). However, granule size distribution did not affect the GT(gelatinization temperature) range, nor did amylose electron microscopy (SEM). SEM also confirmed that there is no relationship between the size and the shape and the amylose content of the rice starch.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.320-325
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• 1985

Relation between amylose and physical properties of milled rice was investigated. Amylose content was negatively and positively correlated with chalkiness and alkali solubility, respectively. No correlation was observed between amylose content and water uptake rate, cooked rice hardness or relative crystallinity. Relative crystallinity of the starch was negatively correlated with alkali solubility and water uptake rate.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.1
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• pp.66-71
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• 1993

Several trials and errors were repeated to develop a simplified recipe of amylose analysis using a Rapid Flow Autoanalyzer(Alpkem, RFA-300). The amylose content of rice samples analyzed by the Rapid Flow Autoanalyzer were compared with those of Williams’ and Juliano’s assay. The results by the simplified recipe of RFA amylose analysis were highly correlated with those by Williams’ and Juliano’s method(r=0.95$^{**}$-0.97$^{**}$). The relative amylose content of defatted rice starch was higher than those of non-defatted rice flour, showing very close correlations between those analyzed by three method.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.3
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• pp.497-503
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• 1996

In order to obtain basic data for the preparation of rice flour, chemical properties of grain layers were compared using Chucheongbyeo and Samgangbyeo, which are Japonica and Tongil type rice, respectively. The amylose contents of L6(center) layer in two different type of rice were the highest among 6 layers of rice grain tested. Reduction in amylose content was observed as the layer reached the surface, resulting in the lowest amylose content in the L0 layer. Amylose contents of L6 layer of Chucheongbyeo and Sangangbyeo were 3 and 2.2 times higher than those of L1 layer, respectively. Crude protein content of the L2 layer was the highest among 6 layers of rice grain tested and 2.2~2.5 times higher than that of whole milled rice. Crude fat content of grain layer was reduced as reaching the center layer. The crude fat contents of L6 layer of grain were 0.21% and 0.25% in Chucheongbyeo and Samgangbyeo, respectively. Most of free and bound lipids in L0 layer of two different rices were 69 : 31 and 79.5 : 20.5, respectively. Bound lipid content of grain layers increased as reaching the center layer. Major fatty acids in free lipids of both cultivars were linoleic acid, oleic acid, and palmitic acid. Linoleic acid content was higher than oleic acid in Chucheongbyeo, but oleic acid content was higher in Samgangbyeo. Palmitic and myristic acid contents of Chucheongbyeo were higher than those of Samgangbyeo, but stearic and linolenic acid contents were lower than those of Samgangbyeo.