• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.3
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• pp.276-280
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• 1991

The quality changes of brown rice during storage were determined by the method of quantitative analysis of n-hexanal, amylogram, texture and volume expansion. The qualities of stored brown rice were also analyzed with sensory evaluation of cooked milled rice obtained from brown rice, n-Hexanal content, peak viscosity and total setback of brown rice flour pastes increased substantially with the increased of storage period at 35$^{\circ}C$. Up to 10 months of storage at 35$^{\circ}C$, stale flavor obtained by a sensory method markedly increased, but stickiness decreased. The scores of overall preference were in good agreement with those of stale flavor (r=-0.98) and sticky texture (r=0.98). The correlation coefficient between stale flavor obtained by a sensory method and instrumetal analysis for stored brown rice was r=0.97.

• Korean Journal of Food Science and Technology
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• v.49 no.5
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• pp.469-473
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• 2017

The objective of this study was to develop methods for the discrimination of new and stale rice by using an electronic eye. To develop the discriminant, 107 rice samples produced in the years 2015 and 2016 were investigated. After the rice was treated with guaiacol, oxydol, and p-phenylenediamine reagents, an electronic eye was applied to discriminate between newly harvested rice and rice stored for 1 year. Out of the 4,096 color codes of the electronic eye, 31 color codes were identified for the discrimination of newly harvested rice and rice stored for 1 year. The classification ratio of newly harvested rice and rice stored for 1 year was 100% and the discrimination accuracy for unknown samples was 100%. In a total of 150 mixtures of new rice and stale rice, the discrimination accuracy was between 16.7 and 95.6%, depending on the mixing ratio. This capability of the electronic eye will be useful as a tool for discriminating the production year of rice.

• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.749-755
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• 2021

The objective of this study was to investigate the physicochemical properties of rice starch extracted from stale rice using alkaline steeping (AKL) and improved enzymatic digestion (iENZ) methods. The crude protein content (0.5-0.7%) of stale rice starch (SRS) was less than 1% by iENZ, but not so when measured by the existing ENZ methods. SRS is an intermediate amylose rice starch. AKL-SRS and iENZ-SRS exhibited typical A-type crystal packing arrangements with similar relative crystallinities. iENZ-SRS showed higher gelatinization onset and peak temperatures with a narrower gelatinization temperature range, compared to those of AKL-SRS, indicating that iENZ annealed SRS. Thus, iENZ-SRS exhibited lower swelling power and solubility, and higher pasting viscosities with delayed viscosity development. Overall, the use of stale rice as a rice starch source could make economical production of rice starch possible, and iENZ may diversify rice starch characteristics, which expands the utilization of rice starch in food and non-food industries.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.2
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• pp.105-112
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• 2017

The mixing of rice and brown rice produced in different years is banned in Korea by the grain management act. However, there has been no reported method for discriminating the production year of rice. The objective of this study was to develop a method for discriminating the production year of rice and brown rice based on their phospholipids content. One hundred rice samples and 130 brown rice samples produced between 2012 and 2015 were collected. Twelve phosphatidylcholine components were analyzed by liquid chromatography-tandem mass spectrometry. Phosphatidylcholine was used as an internal standard to calculate the peak intensity of the samples. A statistical analysis of the results showed that the centroid distance between the stale and new rice was 4.16 and the classification ratio was 97%. To verify the calculated discriminant, 61 and 40 rice samples were collected. The accuracy of discrimination was 82% by primary verification and 80% by secondary verification. The statistical analysis of brown rice showed that the centroid distance between the stale and new brown rice was 3.14 and the classification ratio was 96%. To verify the calculated discriminant, 10 samples of new rice and 30 samples of stale rice were collected and the accuracy of discrimination was 93%. The accuracy of discrimination for rice stored at room temperature was 57.9-92.1% and that for rice stored at a low temperature was 86.8-94.7%, depending on the storage period. For brown rice, the detection accuracy was 94.7-100% at room temperature and 92.1-100% at a low temperature, depending on the storage period. The accuracy of discrimination for rice was affected by the storage temperature and time, while that for brown rice was more than 92% regardless of the storage conditions. These results suggest that the developed discriminant analysis method could be utilized to determine the production year of rice and brown rice.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.69-69
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• 2017

Due to the lack in storage facility, considerable amount of rice is stocked in the open air, which causes increased stale flavor and deteriorates palatability and merchantable quality. Lipoxygenase-3(LOX-3) is involved in the production of volatile constituents in stored rice, and the development of stale flavor is delayed in LOX-3 null rice. LOX activity in the rice grain is localized in bran fraction and the tropical Japonica cultivar 'Dawdam' was reported that the absence of LOX-3 is inherited as a simple recessive trait. Also, it was reported that the peroxidation of unsaturated fatty acids occurs at lower levels in the 'Dawdam' bran fraction during storage than in rice varieties with LOX-3. This study was conducted to develop LOX-3 null rice lines using 'Dawdam' and investigate changes of physicochemical properties of the lines stored at different storage temperatures and periods. So we analyzed texture, toyo glossiness value, germination rate and lipoxygenase activity of 15 LOX-3 null rice lines on the condition of which rough rice had been stored at different temperatures (high temperature condition at $35^{\circ}C$ and low temperature condition at $15^{\circ}C$ for 4months. Hardness and stickiness of the lines tendered to be increased when it was stored at high temperature and adhesiveness, springiness, cohesiveness and chewiness was not considerably different according to storage temperatures and periods. The germination rate of HR29062-B-98-2-1-B among LOX-3 null rice lines was higher than another lines, 99.3, 94.0% after 4months stored at low temperature and high temperature, respectively. The lipoxygenase activity was 3,304, 1,601unit/mg protein after 4months stored at low temperature and high temperatures, respectively. So, it is thought that this line will be useful to breed rice varieties with high storability after tested on agricultural traits.

• Korean Journal of Breeding Science
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• v.51 no.3
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• pp.190-200
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• 2019

It is reported that the absence of lipoxygenase-3 (LOX-3) may contribute to a reduction in stale flavor after the storage of rice. To improve the quality of stored rice of the Korean japonica rice cultivar, we conducted a breeding program to develop near-isogenic rice without LOX-3 in the genetic background of Saenuri, a mega variety of Korea. In the first step of the breeding program, we used a donor parent of LOX-3 null, Daw Dam, and a recurrent japonica parent, Sindongjin, to develop HR27873-AC12 by backcross (BC₁), color test for introgression of lox-3, and anther culture for rapid fixation. In the second step, we used the donor parent, HR27873-AC12, and the recurrent parent, Saenuri, to develop HR28896-31-3-1-1 by backcross (BC₁), marker-assisted selection (MAS) for lox-3, and phenotypic selection (PS) for agronomic traits. Finally, in the third step, we developed HR30960-186-2-1-2-1 (Jeonju624), derived from a cross between Saenuri and HR28896-31-3-1-1, by MAS for lox-3 and PS with high selection pressure for agronomic characteristics. Jeonju624 was confirmed with the introgression of lox-3 by molecular marker. Jeonju624 was a mid-late maturing rice with similar agronomic characteristics to Saenuri, lodging tolerance with short culm, erect plant architecture, and resistance to bacterial blight and rice stripe virus. The yield components of Jeonju624 were mostly similar to Saenuri, except for the 1,000-grain weight of brown rice. The appearance of the grain of Jeonju624 was better than that of Saenuri, and the characteristics of cooked rice were similar to those of Saenuri. In the genetic background analysis using 406 KASP (Kompetitive Allele-Specific PCR) markers, Jeonju624 was confirmed to be the near-isogenic line (NIL) of Saenuri with a 95.8% recovery rate. Jeonju624 is the NIL of Saenuri without LOX-3, and overcomes the linkage drag of Daw Dam with similar agronomic characteristics and genetic background to Saenuri. Jeonju624 can be utilized as a practical cultivar to improve the quality of stored rice, breeding material for the introgression of lox-3, and genetic material to elucidate the effect of introgressed genes.

• Korean Journal of Food Science and Technology
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• v.4 no.4
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• pp.271-275
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• 1972

Effects of solvent extraction by immersion on the quality and storage stability of Korean rice were studied. Proportions of lipid extracted from whole grain of rice by immersing into two volumes(v/wt) of hexane and ethanol for 72 hours at room temperature were 0.41% and 0.38% respectively. Small changes of water content and hardness of rice were observed by solvent treatment. Cooking characteristics; that is, water-uptake ratio. extended volume, total solid, and starch-iodine blue test of rice was markedly changed by ethanol treatment, while little changes were observed by hexane treatment. No considerable differences in moisture sorption isotherm of rice were observed by both solvent treatments. Changes in TBA number and stale flavor appearance of rice treated with or without solvent immersion during storage at $60^{\circ}C$ showed that rice treated with hexane had best storage stability compared to ethanol treatment, while ethanol treatment of rice had better storage stability than no treatment. Similar results were noted in changes of the flavor score of cooked rice samples which were freeze dried.

• Food Science and Preservation
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• v.12 no.4
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• pp.310-316
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• 2005

This study was carried out to investigate the quality characteristics by packaging materials and storage temperature to predict safe storage period for milled rice. Mechanical taste value and whiteness of milled rices stored at room temperature were severely decreased than those of the stored at low temperature, but fat acidity and b value of those at room temperature was rapidly increased than those of stored at low temperature. Milled rice packed in LDPE film bag were smelled stale flavor after 4 months storage at room temperature, Hojinbyeo was not produced flour in the rice grain surface but Dongjinbyeo was showed production of flour. pH of milled rice of Dongjinbyeo and Hojinbyeo packed in LDPE film bag were the lowest showing 5.3 and 5.6, respectively after 6 months at mom temperature. Safe storage period of Dongjinbyeo and Hojinbyeo packed in craft paper bag were 1 month at room temperature, those of packed in LDPE film bag were 2 months. At low temperature safe storage period of Dongjinbyeo and Hojinbyeo packed in craft paper bag were 2 months, those of packed in LDPE film bag were 5 and 4 months, respectively.