• Applied Biological Chemistry
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• v.34 no.4
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• pp.379-385
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• 1991

Morphological changes of starch granules from 12 different varieties of rice were examined by scanning electron microscopy during heating at 2.5% (w/v) concentration. Rice starch granules proceeded through a similar pattern of progressive morphological changes daring heating, regardless of variety. Rice starch granules began to swell radially in the initial stage of gelatinization and then undergo radial contraction and random tangential expansion to form complex structures in the latter stage of gelatinization temperature range. At higher temperatures, starch granules softened and melted into thin flat discs, and then stretched into thin filaments to form three-dimensional networks. These progressive morphological changes were reflected in the changes of swelling power, solubility and amylograph viscosity of starch. During the transition of melting or softening, swelling power, solubility and amylograph viscosity increased rapidly. The time of loss of granular structure of starch depended on gelatinization temperature range. The ratio of amylose to amylopectin was largely responsible fur the rate of melting or softening and the fineness of a three-dimensional filamentous network above the gelatinization temperature range. Therefore, both the gelatinization temperature range and amylose content of starch affect the rate of cooking, and amylose content of starch affects the final texture of cooked starch paste.

• Journal of Animal Science and Technology
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• v.63 no.3
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• pp.465-474
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• 2021

It has become important to explore alternative feed ingredients to reduce feed costs, which are burdensome for livestock production. In addition, it is desirable to find efficient and functional alternative ingredients for traditional feed ingredients in pig diets, considering the stress and sensitivity of disease of pig. Rice is produced around the world like corn that is the typical energy source in pig diets. Although the nutritional quality varies depending on the degree of milling, rice, except whole grains (paddy rice), contains more starch than corn and its structure and granule size are easier to digest than corn. In addition, the fact that rice has fewer non-starch polysaccharides (NSP) and anti-nutritional factors (ANFs) is also effective in improving digestibility and various polyphenols in rice can help modulation of immune responses, which can be beneficial to the gastrointestinal environment and health of pig. Many studies have been conducted on rice focusing on things such as degree of milling, substitution rates of corn, granule size, and processing methods. Most results have shown that rice can be partially or completely used to replace corn in pig diets without negatively affecting pig growth and production. While further research should focus on the precise biological mechanisms at play, it was confirmed that the use of rice could reduce the use of antibiotics and pig removal and protect pigs from gastrointestinal diseases including diarrhea. From this point of view, rice can be evaluated as a valuable feed ingredient for swine diets.

• Journal of Crop Science and Biotechnology
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• v.11 no.4
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• pp.227-232
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• 2008

Drought stress is one of the major abiotic stresses in agriculture worldwide. We report here a proteomic approach to investigate the impact of post-fertilization drought on grain quality in rice seed endosperm (Oryza sativa cv. IR-64). Plants were stressed for 4 days at 3 days before heading. Total proteins of endosperm were extracted and separated by two-dimensional gel electrophoresis. Not many protein spots showed differential accumulation in drought-stressed samples. More than 400 protein spots were reproducibly detected, including three that were up-regulated and five down-regulated. Mass spectrometry analysis and database searching helped us to identify six spots representing different proteins. Functionally, the identified proteins were related to protein synthesis and carbohydrate metabolism, such as Granule-Bound Starch Synthase (GBSS, Wx protein), which is thought to play a very important role in starch biosynthesis and quality, a very crucial factor in determining rice grain quality.

• Korean journal of food and cookery science
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• v.7 no.4
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• pp.71-86
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• 1991

This study was attempted to enhance nutritional value of cooked rice by adding milk in cooking water. Cooked and soaked rice with five different levels of milk in cooking water (0%, A: 30%, B: 50%, C: 70%, D: 100%, E) was tested for rheological parameters, fine structural changes, sensory evaluation. 1. Water absorbance of raw rice in cooking water with varying amountes of milk, was tested at $5^{\circ}C$ and $15^{\circ}C$ for 2 hours. Water absorption ratio was decreased as milk content was increased and soaking temperature was low. Time for maximum water absorption of sample A was 40 min at 1$15^{\circ}C$ but for sample B to D, it was not reached until 120 min. 2. Electronmicroscopic observation revealed that starch granules of rice lost their regular forms by soaking for 90 minutes, but recovered most of initial regularity after 24 hours. Increase in milk content of soaking water decreased marginal sharpness of the starch granule, presumably due to reduced swelling of the granule. 3. Degree of gelatinization of cooked rice was highest in sample A and progressively decreased as milk content was increased. It was, however, increased in all samples when the cooking water to rice ratio was raised from 160% to 180%. During 4 hour storage, rates of retrogradation were not different between A and B samples, but those of C, D and E were about 2.5 times higher than A and B under the optimal condition of 170% cooking water to rice ratio. This was in the order reverse to hardness order of AC>A, D＞E at cooking water to rice ratios of 160% and 170%, above which A sample surpassed the rest of samples. 4. Sensory evaluation conducted by fifteen university students as panelists showed that there were more significant differences among five samples in flavour, texture than appearance and a notable preference for b and C over A, D and E.

• Journal of the East Asian Society of Dietary Life
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• v.7 no.1
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• pp.47-55
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• 1997

This study aims to know what the physicochemical properties and physical properties of the Korean traditional rice cake injulmi made from persimmon powder and glutinous rice(powder), and to come up with a standard recipe of it with the premixed powder of persimmon and glutinous rice. Cooked rice powder with 9 different levels of persimmon in cooling dough(75, 100 and 150${\mu}{\textrm}{m}$ power with each 20, 40, and 60%) was tested for rheological parameters, the rate of swelling, degree of gelatinization, sensory evaluation, and the observation of cross section used to electronmicroscope. 1. sensory evaluation conducted by 20 university students as panelists showed that mixed glutinous rice powder and persimmon powder lost their regular forms. increase in persimmon powder content increased a thin layer of starch granule, presumably due to sugar and fiber in the mixed persimmon powder granule. 3. In cooking the rice cake with 20~60% of persimmon, it showed 6.3 to 5.5 pH. 4. Quantitative description analysis conducted by 20 university student s panelists showed that sample that sample C was preferred among 9 samples. From these results, it was concluded that glutinous rice cake cooked with 20% of persimmon powder was quiet acceptable. Optimum cooking condition for the glutinous rice with persimmon powder rice cake was 30min of cooking time and 25$0^{\circ}C$ of cooking temperature with gas oven.

• Korean Journal of Food Science and Technology
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• v.27 no.3
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• pp.306-312
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• 1995

In order to know properties in rice starch during storage of rice, rice starch from stored rice(stored at $5^{\circ}C$, R.H. 65% and $30^{\circ}C$, R.H. 85%, for 16 weeks) used in this experiment. Water binding capacity of rice starch increased for 8 weeks, and then it decreased. As the storage period took longer, swelling power and solubility, optical transmittance, blue value, total amylose content and soluble amylose content decreased. For the same periods, changes in rice starch from stored rice$(30^{\circ}C$, R.H. 85%) were made more than those in rice starch at $5^{\circ}C$, R.H. 65%. The granule shape of rice starch, irrespective of storage periods and conditions, didn't make a significant difference. The relative crystallinity of the rice starch by X-ray diffraction didn't distinctly changed till the second week. But, at the fourth week, that by X-ray diffraction significantly decreased, and then slightly decreased. As the storage period took longer, gelatinization temperature, melting temperature and melting enthalpy measured by DSC got higher, but gelatinization enthalpy got lower. For the same storage period, gelatinization temperature, melting temperature, gelatinization enthalpy and melting enthalpy of rice starch stored at $30^{\circ}C$, R.H. 85% made changes more than those of rice starch stored at $5^{\circ}C$, R.H. 65% did.

• Korean Journal of Breeding Science
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• v.42 no.1
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• pp.1-10
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• 2010

Five mutants were investigated at the molecular level to determine the factors responsible for mutated endosperm types. They were classified as high (HA) or low amylose (LA) phenotypes based on the amylose content in endosperm. The five were previously produced from Ilpum and Shindongjin cultivar treated with N-methyl-N-nitrosourea and gamma-ray irradiation, respectively. Analysis of the genomic structure and expression of Granule-bounded Starch Synthase I (GBSSI) genes revealed that mutants generally showed a higher incidence of nucleotide transition than transversion, and the $A:T{\rightarrow}G:C$ transition was particularly prevalent. The rates of nucleotide substitution in HA mutants were generally higher than those in the LA mutants, leading to higher substitutions of amino acid in the HA mutants. Neither nucleotide substitutions interfering with intron splicing or causing early termination of protein translation were found, nor any large-sized deletions or additions were found in all the mutants. In principle, amylose content can be regulated by three factors: internal alterations of GBSSI protein, the strength of gene expression, and other unknown external factors. Our results indicate that the endosperm mutants from Shindongjin arose from internal alterations of GBSSI proteins, which may be the result of amino acid substitutions. On the other hand, the Ilpum mutants might be principally caused by the alteration of gene expression level. Analysis of another three glutinous cultivars revealed that the major factor leading to glutinous phenotypes is the 23-bp duplicative motif (5'-ACGGGTTCCAGGGCCTCAAGCCC-3') commonly found in exon 2, which results in the premature termination of protein translation leading to the production of a non-functional GBSSI enzyme.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.3
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• pp.99-105
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• 2023

Starch characteristics and pasting properties of Tongil-type rice varieties with different amylose content were analyzed. Three different Tongil-type rice varieties and one Japonica-type rice variety were examined for their properties. Tongil-type rice varieties have longer panicles and higher rice yield (721-765 kg per 10a) than Boramchan, a Japonica-type high-yield rice variety. The protein content of the Tongil-type rice variety was higher than that of Boramchan. Japonica-type rice varieties had lower amylose content than Japonica-type rice varieties, except for Amimyeon (Milyang355). Amimyeon had higher protein content than the other varieties, and its amylose content was particularly high at 39.2%. The distribution of starch granule sizes of the four varieties was similar, and the particle size corresponding to D50 was approximately 87.8-81.9 ㎛. The pasting properties of rice flour varied among varieties. The Dasanbyeo and Hanarum2 amylogram patterns were similar. These two varieties had a higher peak viscosity (PV) and lower setback (SB) than Boramchan. In the case of Amimyeon, the hot paste viscosity (HPV), cool paste viscosity (CPV), and SB were significantly higher than those of the other Toingil-type varieties, and the breakdown (BD) was very low, showing pasting properties significantly different from that of the other varieties. The onset (T_o), peak (T_p), and conclusion temperature (Tc) of gelatinization of rice flour from Amimyeon were lower than those of the other tested varieties. In addition, the gelatinization temperature, measured using differnetial scanning calorimetry (DSC), and BD, measured using al rapid visco analyzer (RVA) were low in Amimyeon. Amylose content showed a high positive correlation with pasting time (PTi), HPV, and SB and a negative correlation with PV and BD.

• Proceedings of the Korean Society of Crop Science Conference
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• 2019.04a
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• pp.101-101
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• 2019

• Applied Biological Chemistry
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• v.33 no.1
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• pp.1-7
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• 1990

Starch samples of rice and glutinous rice starches were adjusted to 27 % of moisture and heated at $100^{\circ}C$ for 16 hours, respectively. After the treatment, their physicochemical properties were investigated. The granule shapes of all the starches were polygonal and they became slightly bigger in their sizes after the treatment. All their X-ray diffraction patterns were A types. The specific gravity of the starches decreased to 1.03-1.09 by the treatment. The water binding capacity of rice starches increased, while that of glutinous counterparts slightly decreased. Almost no change in the amount of amylose included was found. Swelling power and solubility were increased with the increase of temperature. At a certain temperature, however, the solubility of the treated starches increased when the swelling power decreased. The initial gelatinization temperatures of Akkibare, Yongmun, and Taebaek starches were $60{\sim}65^{\circ}C$ but those of glutinous rice starch and U.S.A. rice starch were $55{\sim}60^{\circ}C$ and $70{\sim}75^{\circ}C$, respectively, as measured by transmittance. The gelatinization temperature of the treated starches was higher than that of the untreated starches.