• 제목/요약/키워드: storage of rice

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Antioxidative Activity of Rice Grain using FI-CL and ESR Methods

  • Chung, Ill-Min;Kim, Kwang-Ho;Ahn, Joung-Kuk;Lee, Si-Kyung;Lee, Jin-Ohk
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.46 no.5
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    • pp.411-415
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    • 2001
  • Fifty-four Korean native and 28 foreign rice varieties harvested in 1998 and 1999 were examined for antioxidative activity that is measured to a chemiluminescence and superoxide radical intensity, by the flow injection chemiluminescence (FI-CL) system and an electron spin resonance (ESR) spectrophotometer, respectively. In the chemiluminescence measurement by FI-CL, radical scavenger activity did not differ significantly among rice varieties between origin types of rice varieties, and between storage periods. GinSun and Hongchoengdo, colored rice exhibited high electron scavenging effect by ESR. Therefore, these results indicate that the pigments of rice varieties may play important antioxidative roles and that it may be possible to breed rice varieties with higher antioxidative potentials.

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Optimum of Gamma Irradiation Dose for Rice-based Infant Foods with Improved Energy-density and Shelf-life (쌀기본 이유식의 에너지 밀도 및 저장성 증대를 위한 최적 감마선 조사 선량)

  • 이유석;오상희;이주운;김장호;김재훈;김관수;김왕근;변명우
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.33 no.5
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    • pp.894-898
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    • 2004
  • This study was carried out to determine the optimum irradiation dose for infant foods with improved energy-density and extend shelf-life using gamma irradiation. Rice and rice porridge were irradiated at 0, 2.5, 5, 7.5, 10, 15 and 20 kGy, and rheological characteristics and total plate count of porridge were evaluated for 6 weeks. Rice and rice porridge at 2.5 kGy dose reduced the viscosity with 22% and 98%, respectively. The result of total aerobic bacteria of non-irradiated rice porridge was 6 log CFU/g and that of 2.5 kGy irradiated rice porridge on 2 weeks storage was 3 log CFU/g, while that of 7.5 kGy irradiated sample was not detected even at the end of storage. Irradiation on rice-based porridge was proper to enhance the total solid in inverse proportion to considering viscosity and extend shelf-life. Gamma irradiation was effective technology in enhancing calorie value of porridge due to reduction of viscosity.

Trend and Further Research of Rice Quality Evaluation (쌀의 품질평가 현황과 금후 연구방향)

  • Son, Jong-Rok;Kim, Jae-Hyun;Lee, Jung-Il;Youn, Young-Hwan;Kim, Jae-Kyu;Hwang, Hung-Goo;Moon, Hun-Pal
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.47
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    • pp.33-54
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    • 2002
  • Rice quality is much dependent on the pre-and post harvest management. There are many parameters which influence rice or cooked rice qualitys such as cultivars, climate, soil, harvest time, drying, milling, storage, safety, nutritive value, taste, marketing, eating, cooking conditions, and each nations' food culture. Thus, vice evaluation might not be carried out by only some parameters. Physicochemical evaluation of rice deals with amy-lose content, gelatinizing property, and its relation with taste. The amylose content of good vice in Korea is defined at 17 to 20%. Other parameters considered are as follows; ratio of protein body-1 per total protein amount in relation to taste, and oleic/linoleic acid ratio in relation to storage safety. The rice higher Mg/K ratio is considered as high quality. The optimum value is over 1.5 to 1.6. It was reported that the contents of oligosaccharide, glutamic acid or its derivatives and its proportionalities have high corelation with the taste of rice. Major aromatic compounds in rice have been known as hexanal, acetone, pentanal, butanal, octanal, and heptanal. Recently, it was found that muco-polysaccharides are solubilized during cooking. Cooked rice surface is coated by the muco-polysaccharide. The muco-polysaccharide aye contributing to the consistency and collecting free amino acids and vitamins. Thus, these parameters might be regarded as important items for quality and taste evaluation of rice. Ingredients of rice related with the taste are not confined to the total rice grain. In the internal kernel, starch is main component but nitrogen and mineral compounds are localized at the external kernel. The ingredients related with taste are contained in 91 to 86% part of the outside kernel. For safety that is considered an important evaluation item of rice quality, each residual tolerance limit for agricultural chemicals must be adopted in our country. During drying, rice quality can decline by the reasons of high drying temperature, overdrying, and rapid drying. These result in cracked grain or decolored kernel. Intrinsic enzymes react partially during the rice storage. Because of these enzymes, starch, lipid, or protein can be slowly degraded, resulting in the decline of appearance quality, occurrence of aging aroma, and increased hardness of cooked rice. Milling conditions concerned with quality are paddy quality, milling method, and milling machines. To produce high quality rice, head rice must contain over three fourths of the normal rice kernels, and broken, damaged, colored, and immature kernels must be eliminated. In addition to milling equipment, color sorter and length grader must be installed for the production of such rice. Head rice was examined using the 45 brand rices circulating in Korea, Japan, America, Australia, and China. It was found that the head rice rate of brand rice in our country was approximately 57.4% and 80-86% in foreign countries. In order to develop a rice quality evaluation system, evaluation of technics must be further developed : more detailed measure of qualities, search for taste-related components, creation and grade classification of quality evaluation factors at each management stage of treatment after harvest, evaluation of rice as food material as well as for rice cooking, and method development for simple evaluation and establishment of equation for palatability. On policy concerns, the following must be conducted : development of price discrimination in conformity to rice cultivar and grade under the basis of quality evaluation method, fixation of head rice branding, and introduction of low temperature circulation.

Kinetics for Quality Changes of Rice and Rice flour during Storage (쌀 및 쌀가루의 저장중 품질 변화에 대한 Kinetics)

  • Kim, Byeong-Sam;Park, Noh-Hyun;Shin, Dong-Hwa
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.17 no.3
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    • pp.220-225
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    • 1988
  • Rice and rice flour were stored at $13^{\circ}C$, $23^{\circ}C$ and $38^{\circ}C$ for 6 months and Quality indicator according to the correlation between physicochemical properties and sensory scores, was monitored. rat acidity was the most effective indicator for quality changes during storage and its increasing rate showed 1st-order reaction kinetics. The Arrhenius activation energies were 50,953 KJ/Kmol in rice and 59,750 KJ/Kmol in rice flour. On the basis of relation between the acceptable sensory score(3.0) and fat acidity, shelf-life of rice and rice flour were 378 and 358 days at $13^{\circ}C$ and 163 and 145 days at $23^{\circ}C$, respectively.

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Occurrence and Repression of Off-Odor in Cooked Rice during Storage under Low Temperature Warming Condition of Electric Rice Cooker (전기밥솥으로 저온보온한 쌀밥의 이취 발생 및 억제)

  • Park, Seok-Kyu;Ko, Yong-Duck;Cho, Young-Sook;Shon, Mi-Yae;Seo, Kwon-Il
    • Korean Journal of Food Science and Technology
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    • v.29 no.5
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    • pp.919-924
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    • 1997
  • The changes in physicochemical properties of cooked rice stored in an electric rice cooker at different temperature (63, 66, 69 and $72^{\circ}C$) were investigated. The growth of thermophilic bacteria was gradually increased in all samples with storage time up to 6 hours and increased rapidly afterward. The bacterial growth rate was higher during storage at low temperature than at high temperature, and the bacterial number generally reached the maximum at 18 hours of the storage. The number of bacteria in sample stored at $63^{\circ}C$ was increased to $10^6$ CFU/g after storage for 6 hours. The heat treatment at 6 hours of storage decreased the bacterial number to $10^5 $ CFU/g at 8 hours of storage. Bacterial number was gradually increased with storage time after the first heat treatment. When the sample was reheated after 8 hours of storage, the bacterial number was reduced to the level at which off-odor was not detected after storage for 24 hours. During the storage, moisture content of heat-treated sample was lower than that of sample stored at $63^{\circ}C$ but higher than that of sample stored at $72^{\circ}C$. The L value of heat-treated sample was higher than that of the sample stored at $72^{\circ}C$, but lower than that of the sample stored at $63^{\circ}C$. The b value showed an opposite trend to the L value with regard to the storage temperature. Changes in texture were not remarkable during the storage for the sample heat-treated and stored at low temperature. The occurrence of off-odor and browning was depressed in the heat-treated sample, and the texture and overall eating quality were more acceptable than the samples stored at low temperature.

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A study on the Development of Standardized Recipe and the Microbiological Assessment and Sensory Evaluation of Korean Traditional Starch Foods for Steam Convection Oven and Cook/Chill System for Kindergarten Foodservice Operations (유치원 급식에 적용하기 위한 한국의 전통적인 전분류 음식의 Steam Convection Oven 및 Cook/Chill System용 레시피 개발 및 미생물적, 관능적 품질 평가에 대한 연구)

  • 강현주;김경자;김은희
    • Korean journal of food and cookery science
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    • v.14 no.4
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    • pp.348-357
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    • 1998
  • To meet the demand for high quality of foods with the expanded implementation of foodservice into kindergarten, and to make the efficient use of resources, the necessity of introducing central production unit with cook/chill system into kindergarten foodservice is getting increased. The purpose of this study were to develop standardized recipe applicable to cook/chill system for kindergarten foodservice and to evaluate the microbial and sensory quality. For quantitty production of cook/chill system in kindergarten foodservice, Korean traditional starch foods were selected as menu items. The followings are summary of the results: 1. Standard recipes to produce Various Boiled Rice (Boriebap and Yackbap) and Rice Cake (Chapsal-pat-sirutuk) for cook/chill system have been developed. 2. The microbial quality of Boribap, Yackbap and Chapsal-pat-sirutuk during 10 days chilled storage was very excellent. And in this experiment, the stability of storage of standard recipes of Boribap, Yackbap and Chapsal-pat-sirutuk at cook/chill system was proved for 10 days. 3. In the result of sensory evaluation, apperance of Boribap was decreased significantly on the third day of storage (p<0.005). The rest of the item of sensory evaluation of Boribap has no significance between the first day and the third day of storage. The tenderness (p<0.05) and gelatinousness (p<0.005) of Yackbap had been rated high significantly in the third day of storage than the first day of storage. The rest of the item of sensory evaluation of Boribap has no significance between the first day and the third day of storage. The color and chewiness of Chapsal-pat-sirutuk was decreased significantly on the third day of storage (p<0.05). The rest of the item of sensory evaluation of Chapsal-pat-sirutuk has no significance between the first day and the third day of storage.

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Quality Characteristics of Backsulgi with Dextrinized Rice (호정화에 의한 백설기의 품질특성)

  • Doo, Hwa-Jin;Lee, Eun-Suk;Kim, Yong-Ro;Shim, Jae-Yong
    • Food Engineering Progress
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    • v.13 no.4
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    • pp.289-296
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    • 2009
  • The purpose of this study was to investigate the effect of dextrinization methods (dry oven and roaster) and the ratio of dextrinized rice on the quality of Backsulgi during storage. The moisture content significantly increased with increasing the amount of dextrinized rice regardless of dextrinization methods. As the ratio of dextrinized rice increased, the L value of the Backsulgi decreased, but the a and b values increased. The a and b values of dry oven method were higher than those of roaster method due to their thermal denaturalization. However, there were no significant pattern's change in sample's colors during storage. In the texture profiles, the hardness, cohesiveness, gumminess and chewiness significantly decreased with increasing the amount of dextrinized rice depending on the dextrinization methods and the ratios. The time constant (1/k) of the Backsulgi with dextrinized rice comparatively higher than that of control and appeared to be the highest in the Backsulgi formulated by 100% of dextrinized rice. In the sensory evaluation, Backsulgi with dextrinized rice over 30% after 1day storage showed higher value in overall quality and lower value in hardness than control. The addition of 30% dextrinized rice made by roaster showed the most effective on the quality and retrogradation of Backsulgi.

The Effects of the Addition of Cheese in the Manufacture of Rice Cakes Colored with 5 Vegetable-Derived Natural Coloring Materials (오색(五色) 채소 유래 천연 색소를 이용한 건강 맞춤형 컬러 치즈 떡 개발에 관한 연구)

  • Choi, Heeyoung;Lee, Seunggu;Choi, Haneul;Park, Jonghyuk;Heo, Changki;Oh, Jeonhui;Oh, Hyunhee;Jung, Hookil
    • Journal of Dairy Science and Biotechnology
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    • v.31 no.1
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    • pp.85-91
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    • 2013
  • In this study, the effects of adding cheese in the manufacture of rice cakes having 5 different vegetable-derived natural coloring materials were investigated with respect to quality characteristics during storage. Rice cake samples were prepared without (control) or with the addition of 2.0%, 3.0%, or 4.0% cheese. Changes in pH, external appearance, total solid content, and scanning electron microscopy (SEM), texture and sensory characteristics were monitored during storage. The sensory and texture characteristics of the rice cakes with cheese were investigated with respect to color, flavor, and overall acceptability. The total solid content and pH of the cheese-treated rice cakes were higher than that of the control during storage. Rice cakes added with cheese had higher liquid flavor than control. Results revealed that rice cakes added with cheese at less than 4% addition had the best taste, appearance, and sensory properties. Moreover, the addition of cheese to five-colored rice cakes provides additional nutrients while maintaining flavor and quality.

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Effects of Low-Temperature Storage of Brown Rice on Rice and Cooked Rice Quality (현미 저온저장이 쌀과 밥의 품질에 미치는 영향)

  • Choi, Yoon-Hee;Kim, Sun-Lim;Jeong, Eung-Gi;Song, Jin;Kim, Jung-Tae;Kim, Jae-Hyun;Lee, Choon-Gi
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.53 no.2
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    • pp.179-186
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    • 2008
  • This study was carried out to investigate the changes of brown rice, and cooking properties after milling of brown rice according to storage temperature and varieties. Brown rices were stored at $15^{\circ}C$ and $35^{\circ}C$ for 10 weeks. Tz values of brown rice stored at $35^{\circ}C$ were higher in Hwaseongbyeo, Koshihikari, Hitomebore, than the other varieties. The increasing rate of hardness of cooked rice in Odaebyeo, Junghwabyeo, Sangmibyeo stored at $35^{\circ}C$ were lower than those of other varieties. In stored brown rice at $15^{\circ}C$ and $35^{\circ}C$, correlations between pH of brown rice and fat acidity, hardness, b value of cooked milled rice and head rice rate of milled rice were significant $0.743^{**}$, $0.539^*$, $-0.693^{**}$, 0.250, respectively. At $15^{\circ}C$ and $35^{\circ}C$, correlations between L value and b value of cooked milled rice, head rice rate of milled rice were significant $-0.772^{**}$, $0.638^*$, and those between fat acidity of brown rice and consistency of milled rice were $0.604^*$. In brown rice stored at $15^{\circ}C$, It was higher quality of milled rice and cooked rice than those at $35^{\circ}C$ that increased head rice rates of milled rice and glossy value of cooked milled rice but lower color b value and hardness of cooked rice.

Effect of Aging on Physicochemical and Pasting Properties of Nonwaxy Rice Flour and its Starch (쌀의 저장기간에 따른 쌀가루와 생전분의 특성)

  • Kim, Wan-Soo
    • Korean Journal of Human Ecology
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    • v.14 no.6
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    • pp.1037-1046
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    • 2005
  • Using three consecutive years' harvested rices and their starches isolated from rice flours by alkaline method, it was found that no significant aging effect on rice flour and starch was observed based on following results. Proximate data of flours or starches showed in similarity, except high level of crude fat in rice flour and rice starch harvested in 2002. In SEM, the surface of aged rice flour had slightly layered shape due to possible abrasion during storage, and that of aged starch showed more smooth and less rigid polygonal shape. X-ray diffraction patterns of flours and starches were all A type, and crystallinity of rice starch harvested in 2000 had the smallest. From tristimulus colorimetry (Hunterlab Color), total color difference ($\Delta$E) calculated from L, a, and b gave less color difference with the darkest in 2002 harvested one among flours and the lightest in 2001 one among starches. WBCs of both 2002 rice flour and starch were the lowest among samples studied. At 80$^{\circ}C$, swelling power and solubility of rice starches harvested in 2000, 2001 and 2002 were 14.35, 9.75; 14.04, 9.6; and 12.49, 8.82, respectively. The highest peak viscosities measured by RVA were shown both in 2001 rice flour and in its starch. Starch and milled rice flour harvested in 2000 had higher hydrolytic $\alpha$-amylase, compared to other flour and starch samples.

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