• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.5
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• pp.700-706
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• 2005

The objectives of this research were to analyze physicochemical properties of physically modified rice starch which was prepared by hydro-shear homogenizer and ultrasonic homogenizer. The 5:1 of water to starch ratio, 20,500 rpm of hydro-shear homogenizer, and 5 sec of pulse and 40 kHz of frequency of ultrasonic homogenizer, which were operated for 10 min. The 1/3 of size reduction of raw rice starch and gelatinized rice starch, and reduced of particle size were achieved by above processing conditions. The homogenization of raw rice starch and gelatinized rice starch were higher values of specific area, transmittance, solubility and swelling power than control. While, these had lower value of apparent viscosity than control. In raw rice starch, the gelatinization characteristics of ultrasonic homogenizer treated rice starch had some higher values of gelatinization temperature, peak temperature and enthalpy than those of control. While, those of hydro-shear homogenizer treated rice starch had similar values to those of control.

• Korean Journal of Food Science and Technology
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• v.51 no.5
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• pp.432-437
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• 2019

The objective of this study was to determine the molecular/crystalline structures and phase transition properties of starches isolated from six rice cultivars grown in Korea. Apparent amylose content was highest in starch obtained from the Saemimyeon cultivar (30.8%) and lowest in that obtained from the Sheonhyangheukmi cultivar (20.3%). Starch from the Saemimyeon cultivar had a lower proportion of short chains (DP 6-12) and a the higher proportion of long chains (DP${\geq}37$) than that seen in other rice starches. Saemimyeon had relatively higher pasting temperature ($86.5^{\circ}C$), gelatinization temperature ($72.1^{\circ}C$) and gelatinization enthalpy (14.2 J/g) than these values found for other rice starches. The onset temperature and enthalpy for ice crystallization of rice starch ranged from $-27.1{\sim}-20.2^{\circ}C$ and 241.1~264.8 J/g, respectively. The ice melting enthalpy measured in excess water (67% water content) of rice starches was 282.4~310.1 J/g. Among the rice starches examined, starch obtained from Sheonhyangheukmi, with the lowest amylose content, showed the lowest glass transition temperature (${T_g}^{\prime}$).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.513-523
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• 1993

Varietal difference in structural and physical characteristics of rice starch and interrelationships between these starch properties and the physicochemical components of rice grains were investigated for twenty four rice varieties, which were considerably different in amylose content, gelatinization temperature and gel consistency, to obtain the basic informations for diversifying the utility of rice grains and for developing various rice cultivars adaptable to rice food processing. Wave length of maximum absorbance for blue color reaction of starch-I$_2$ complex was 520nm for glutinous rice and 560～600nm for nonglutinous rice. The higher amylose rice showed the longer wave length but there was considerable difference of the wave length among rice materials with similar amylose content. Varietal difference in frequency distribution of debranched starch molecules by isoamylase hydrolysis was largest in amylose fraction, the longest fraction(Fr. I), and was next bigger in intermediate fraction(Int.Fr.) and the ratio between short and long glucose chain of amylopectin fraction(Fr. III /Fr. II). The Fr. III / Fr II ratio was higher in glutinous rice than in nonglutinous one but it was considerably different among nonglutinous rice varieties without any connection with amylose content. The lower alkali digestible rice showed the longer half-hydrolysis time in acid solution. Both soft and hard gel rice varieties in gel consistency test revealed significant varietal difference of 50% acid hydrolysis time. The harder rice in gel consistency exhibited the less frequency of short branch fraction of amylopectin (Fr. III) and the higher amylose content. Twenty four rice varieties were cleary classified by upper two principal components contracted from structural or physical traits of rice starch and some physicochemical properties of rice grain by principal component analysis. The 1st and 2nd principal components can be characterized to components related with amylose and amylopectin structure respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.3
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• pp.226-231
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• 2013

A total 11 Korean rice cultivar was prepared and investigated for its starch and quality characteristics. Amylose content, damaged starch contnent, water contnent, water absorption index (WAI), water solubility index (WSI), particle size and pasting properties of rice flours were measured. The amylose content of waxy, middle waxy and non waxy type domestic normal rice cultivars were 7.09%, 11.69% and 18.58-21.52%, respectively. Moisture content of 11 Korean rice cultivar were 7.19-13.89%. WAI and WSI did not show variations by amylose contents. Sample with high moisture contents was lower damaged starch contents. Particle size of samples was $27.61-189.67{\mu}m$. Final viscosity and pasting temperature of the samples was shown to rage from 45.54 to 313.94 RVA and from 71.03 to $87.98^{\circ}C$, respectively. In this study, results indicated that samples with low moisture contents tend to shown low particle size and high damaged starch contents regardless waxy, middle-waxy, and non waxy type.

• Korean Journal of Food Science and Technology
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• v.17 no.1
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• pp.5-7
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• 1985

Effect of phosphate (sodium polyphosphate 85%, sodium hexametaphosphate 7% and potassium phosphate 7%) on gelatinization of nonwaxy and waxy rice starches was investigated with X-ray diffractometry. The minimum moisture content for the gelatinization of nonwaxy starches was lowered in the presence of phosphate. The minimum temperature for the gelatinization of 5% starch suspensions was not altered by phosphate. However, the degree of gelatinigation of rice starches at the same temperature was higher in the presence of phosphate, except waxy rice starch.

• Korean Journal of Food Science and Technology
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• v.49 no.1
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• pp.1-7
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• 2017

Molecular structure, physicochemical properties, and in vitro digestibility of starch from Korean rice cultivars for special uses (Baegjinju 1, Hanareum, Deuraechan, and Goami 4) were investigated. The starch from Baegjinju 1 had the lowest amylose content (9.7%) and Hanareum, Deuraechan, and Goami 4 had intermediate amylose (20-25%) contents. Baegjinju 1 had a lower proportion of short amylopectin branch chains than the other rice starches. Hanareum had the lowest relative crystallinity and the highest intensity ratio of $1047cm^{-1}/1022cm^{-1}$ among the rice starches. The starch from Goami 4 had a higher pasting temperature and lower gelatinization enthalpy than the other rice starches. Peak viscosity of rice starch from Baegjinju 1 was substantially higher than peak viscosity of other rice starches. Rice starch from Baegjinju 1 had significantly higher rapidly digestible starch content and lower resistant starch content than other rice starches, whereas there was no significant difference in resistant starch content among the rice starches.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.3
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• pp.184-192
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• 2017

Rice flours from five rice (Oryza sativa L.) varieties with different amylose content were prepared by both wet and dry milling processes. The moisture content of wet-milled rice flours (WMR) was approximately three-times higher than that of dry-milled rice flours (DMR). Water absorption index (WAI), water solubility index (WSI), and swelling power (SP) increased in proportion to temperature. The WAI, WSI and SP values of DMR were higher than those of WMR. Baeokchal (BOC), which is a waxy rice cultivar, had a significantly high WSI value. Pasting properties of DMR, except for the BOC cultivar, resulted in an increase in peak, trough, final, and setback viscosities. The levels of resistant starch in four cultivars, except for Dodamssal (DDS), were under 1%, irrespective of the milling process, whereas the resistant starch contents of DMR and WMR in DDS were 9.18% and 6.27%, respectively. In vitro digestibility of WMR was higher than that of DMR, and the estimated glycemic index of the rice flour varieties ranged from 57.6 to 81.3. Damaged starch content of WMR was less than that of DMR; in addition, a negative correlation was observed between the amylose and damaged starch contents of WMR. These results suggest that the properties of rice flour vary depending on the milling method and flour variety, and could be a reference for selecting the appropriate processing method.

• Proceedings of the SOHE Conference
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• 1998.11a
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• pp.131-131
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• 1998

• Korean Journal of Food Science and Technology
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• v.44 no.5
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• pp.577-582
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• 2012

The purpose of this study was to investigate the preparation and physicochemical characteristics of n-octenylsuccinylated (OSAn) rice starches with different rice amylose contents. Amylose contents of Jinsumi flour and Milyang 261 flour were 15.42 and 20.31%, respectively. After processing by alkali treatment, amylose contents of Jinsumi rice starch and Milyang 261 rice starch were 34.21% and 39.32%, respectively. After OSAn treatment, the degree of substitution and reaction efficiency of Jinsumi starch were higher than those of Milyang 261. The stability of the modified Jinsumi emulsion was higher than that of the Milyang 261 emulsion. Viscosity of the Jinsumi emulsion was higher than that of the Milyang 261 emulsion. When the emulsions were spray dried, modified Jinsumi rice starch showed excellent coating efficiency compared to that of modified Milyang 261 rice starch. Therefore, Jinsumi was more suitable than Milyang 261 to apply for encapsulation as wall materials.

• Applied Biological Chemistry
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• v.39 no.5
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• pp.379-383
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• 1996

The ultrastructure of the compound starch granules and the protein bodies of Odaebyeo rice of early matured variety were examined by light microscope and electron microscope. The endosperm cell appealed rectangular or octangular shape on the cross section. The thickness of cell wall containing of membraneous materials was about $0.5\;{\mu}m$ in diameter. The starch cell was filled compactly with globular or oval shaped compound starch granules with the size of $20{\sim}25\;{\mu}m$ in diameter. The compound starch granules were consisted of central core starch granule and concentrical $2{\sim}3$ layers of starch granules. The average thickness of the starch granules were about $5\;{\mu}m$. Most protein bodies were found in the aleurone layer The globular protin bodies were scattered near the compound starch granules and $2.5{\sim}3\;{\mu}m$ in diameter. The protein bodies composed of central electron dense materials and peripheral electron loose materials in limiting membrane.