• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.705-709
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• 1997

Changes in retrogradation degree of nonwaxy milled rice cooked at different pressure and stored in electric rice cooker at $74^{\circ}C$ were investigated. The moisture contents of nonwaxy milled rice cooked at $1.0{\sim}1.9\;atm\;and\;1.2{\sim}1.5$ water/rice ratio were $59.9{\sim}64.3%$. When nonwaxy milled rice was cooked at high pressure, X-ray diffraction patterns of cooked rice exhibited the V-type having nearly no crystallinity. Retrogradation peak of cooked rice from DSC thermogram was observed in the temperature range of $41.9{\sim}62.4^{\circ}C$ and was not appeared in cooked rice above 1.5 atm. During storage at cooker for 24 hr, retrogradation enthalpy of cooked rice was increased and retrogradation peak was not appeared above 1.7 atm. In cooking and storage of cooked rice, retrogradation degree measured by ${\alpha}-amylase-iodine$ method in high pressure gelatinized samples was lower than that in low pressure gelatinized ones.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.626-631
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• 1993

The effects of mugwort on some physicochemical properties of rice flour, on the viscosity of rice flour pastes (2 and 4%), on the hardness and the freeze-thaw stability of rice flour gels (20 and 40%), and on the degree of gelatinization (DG) of pastes and gels were investigated. By addition of mugwort, water holding capacity, swelling power, and solubility of rice flour were increased. The rice flour pastes became thicker by addition of mugwort, but viscosities of both the rice flour pastes and the rice flour-mugwort pastes, without noticeable difference between them, were decreased during storage at $25^{\circ}C\;and\;4^{\circ}C$ for 7 days. The rice flour gels became firmer by addition of mugwort and hardnesses of both the rice flour gels and the rice flour-mugwort gels were increased during storage, especially at $4^{\circ}C$. DGs, measured by glucoamylase digestion, of pastes and gels were decreased slightly during storage. Freeze-thaw stability of gels was not affected by addition of mugwort.

• Korean Journal of Food Science and Technology
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• v.48 no.2
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• pp.187-191
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• 2016

The objective of this study was to analyze the volatile compounds in rice under various milling degrees using a mass spectrometry-based electronic nose and discriminant function analysis (DFA). Less volatile components were more frequently found in rice with a lower milling degree. Milling degree resulted in a shift of DF1 to the left side of the DFA plot. This indicated that the DF1 scores were correlated with the milling degree of rice. Brown rice was found to have more volatile components regardless of the milling degree. Thus, rice prepared at different milling degrees could be effectively discriminated with electronic nose analysis. Moreover, more volatile components were detected with an increase in storage time. A slight change in volatile components was found with an increase in the milling degree. The electronic nose could predict the milling degree and storage time of rice.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.3
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• pp.582-586
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• 2004

Cooked rice for immunosuppressed patients was irradiated at 0, 5 and 10 kGy, and investigated on the irradiation effect on color, texture, and shelf-life during storage at 3$0^{\circ}C$. Yellowness was significantly increased in cooked rice with the increase of storage period and irradiation dose (p<0.05) and the ratio of adhesiveness/hardness of cooked rice was decreased by irradiation at 10 kGy. The result of total plate count of non-irradiated cooked rice was 7 log CFU/g and that of 5 kGy irradiated cooked rice on 7 day storage was 4 log CFU/g, while that of 10 kGy irradiated sample was not detected even at the end of storage. Irradiation with 5 kGy on cooked rice is proper to prolong the shelf-life considering color, texture, and it was extended to over a month. Further research is necessary to apply the high-dose irradiation for long-term preservation to inhibit color and texture change.

• Korean journal of food and cookery science
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• v.32 no.3
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• pp.253-260
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• 2016

Purpose: To develop fat-free dressing containing a resistant starch (RS) as a dietary fiber, the viscosity and stability of various type RSes prepared from wheat, maize, potato, rice, waxy rice, and amaranth starches were investigated by using Brookfield viscometer. The shape of RS granule in the dressing during storage was also observed. Methods: The viscosity of fat free dressing with different retrograded RS3 (RS3V) prepared from waxy rice starch with 0.1% lemon vinegar and ascorbate mixed solution had higher RS3 that was maintained constant during storage. Annealing and heating prior to cross-linking, and heating after cross-linking increased RS level of RS4 type starches. Results: The viscosities and stabilities of dressings with RS were different depending on starch sources and RS preparation conditions. The heated RS4 (HRS4) increased in viscosity and stability with RS4 addition. Especially the fat-free dressings with HRS4 prepared from rice and waxy rice starches maintained stability regardless of separation after one month storage with only 7% separation after 6 month storages. The shape of RS4 granule in acidic medium of dressing did not change until 6 months. Conclusion: In this study, RS4 made by the rice and waxy rice starches showed high viscosity and maintained stability of the fat-free dressings during storage.

• Food Science and Preservation
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• v.21 no.3
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• pp.308-314
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• 2014

The storage characteristics of milled rice produced using the dry-type (DT), semi-dry-type (SDT), and wet-type (WT) systems were studied. Immediately after rice was milled with these systems, storage experiments on the milled rice were conducted for 12 weeks at three temperatures (10, 20, and $30^{\circ}C$). As the storage period increased, the color (b value) and the fat acidity slowly increased, and the whiteness, moisture content, turbidity, solid matter, and number of total bacteria decreased. The effects of the storage temperature on the moisture content, total number of bacteria, and fat acidity were greater than those of the milling system type. The high storage temperature showed greater potential for increasing the moisture content and the fat acidity and decreasing the total number of bacteria. The initial moisture content of the sample produced using the WT milling system was higher than that of the other samples. Also, the initial turbidity and solid matter of the WT system sample were lower than those of the other samples, but the degree of the decrease was similar to that of the others as the storage period passed. These results showed that the system type and the storage temperature are important factors in the safe storage of wash-free rice. Specifically, the wet type milling system affected the initial quality properties, which made its safe storage period shorter than in the other types.

• Korean Journal of Food Science and Technology
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• v.8 no.2
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• pp.74-79
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• 1976

Two rice varieties in Korea, an Indica type 'Tongil' and a Japonica type 'Jinheung', were stored at $5^{\circ}C$ and $30^{\circ}C$ for six months and the changes in organoleptic quality and lipid components were investigated to obtain the following results. In storage, both varieties brought about increases of hardness, cohesiveness and gumminess, and a decrease of adhesiveness among textural parameters of cooked rice. Storage at $5^{\circ}C$ showed no change in organoleptic quality but storage at $30^{\circ}C$ caused the occurrence of off-flavor in both varieties and a marked decrease of stickiness in Jinheung. Rice samples before storage contained 5-times more free lipids than bound lipids and free lipid content of Tongil was $70{\sim}80%$ of Jinheung. In storage, bound lipids tended to increase slowly while free lipids increased in both varieties at $5^{\circ}C$ and tended to increase in Tongil and to decrease in Jinheung at $30^{\circ}C$. In free lipid fractions of rice samples before storage were found 9 components including triglycerides, free fatty acids and sterol esters and in bound lipid fractions were found 8 components including free fatty acids and sterol esters, as the major components. In storage, changes in lipid components were more remarkable in free lipids than in bound lipids and in Jinheung than in Tongil. It was, therefore, concluded that Tongil variety had a better storage stability than Jinheung variety and the deterioration of rice quality occurred mainly in free lipid fractions during storage.

• Culinary science and hospitality research
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• v.19 no.3
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• pp.130-141
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• 2013

In this study, the mechanical and sensory quality characteristics of bar rice cake, Gareadduk, have been measured from the reference group and the sample groups with 10%, 20% 30% and 40% of defatted rice, containing high dietary fiber. From the general properties of rice powder and defatted rice, the crude protein, crude fat and crude ash of defatted rice were higher than those of rice powder, and especially dietary fiber content of defatted rice was 24.6%, 7-8 times higher than that of rice powder. The moisture content of Gareadduk has declined with increased mixing rate of defatted rice. According to the chromatography test result, its brightness, L-value has declined with increased mixing rate of defatted rice while there was no significant difference for different storage periods. Its redness, a-value, has declined with increased mixing rate of defatted rice and longer storage periods. Its yellowness, b-value, has inclined with increased mixing rate of defatted rice and longer storage periods, which showed no significant difference. Its hardness has significantly increased with increased mixing rate of defatted rice. Also, its hardness has gradually increased with longer storage periods. From the elasticity and viscosity test result, there was no specific tendency, but the chewiness of the sample groups was higher than that of the reference group. The sensory test result showed that the colour and scent of bar rice cake, Gareadduk, were getting stronger with increased mixing rate of defatted rice. The taste of the sample groups was stronger than that of the reference group, and the overall acceptability of the sample groups showed the order of 20%> 30%> 40%> 10%.

• The Korean Journal of Food And Nutrition
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• v.22 no.2
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• pp.185-191
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• 2009

This study investigated the effects of adding hard and soft wheat flour to Korean rice cakes(Karedduk) to retard retrogradation, by examining texture properties and descriptive sensory qualities after 2 and 24 hrs of storage at $5^{\circ}C$. The hard and soft wheat flour were combined with dry rice flour at levels of 0, 5, 10, and 20%. The texture properties, as analyzed by a Texture Analyzer, revealed that the springiness, cohesiveness, and adhesiveness of the rice cakes containing wheat flour were similar to those of the control, while chewiness, gumminess, and hardness were lower compared to the control. Also, in sensory analyses, hardness was significantly different in the rice cakes containing wheat flour compared to the control after 24 hrs of storage at $5^{\circ}C$. Overall, the instrumental texture properties were highly correlated with the sensory characteristics. These results suggest that adding hard and soft wheat flour to Korean rice cakes(Karedduk) is effective at retarding retrogradation.

• The Korean Journal of Food And Nutrition
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• v.23 no.4
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• pp.600-606
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• 2010

The objective of this study was to develop functional rice coated with yacon roots extracts and to evaluate the antioxidant properties and physiological activity of rice coated with yacon extract. The washed rice was coated by spraying yacon extract at 10, 20, 30, and $40^{\circ}Brix$ and dried at room temperature. The moisture contents, color changes, antioxidant properties as total polyphenolics and DPPH radical scavenging activity and instrumental texture property and sensory evaluation change in the yacon root extracts coated rice and uncoated cooked rice were observed during 3 days of storage. Increasing the coating concentration was associated with lower color values(L value) and moisture contents. Total phenolics and DPPH radical scavenging properties generally increased in the cooked rice coated with yacon root extract more than the control (non-coated rice). However, D-20($20^{\circ}Brix$ of the yacon root concentration) resulted in better textural properties and sensory overall acceptability in cooked rice on 0 and 3 storage days. It was concluded that the optimum coating ration of rice and added functional yacon rice were $20^{\circ}Brix$ and 7% respectively, in proportion to the total weight of raw rice.