• Title, Summary, Keyword: rice quality

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Comparison of starch properties of rice varieties in different eating quality

  • Yoon, Mi-Ra;Kwak, Jieun;Lee, Jeong-Heui;Lee, Jeom-Sig;Kim, Mi-Jung;Jung, Tae-Wook
    • Proceedings of the Korean Society of Crop Science Conference
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    • pp.295-295
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    • 2017
  • Rice (Oryza sativa L.) is one of the most important food crops in the world. The eating quality of cooked rice is the most important trait japonica rice breeding in Korea. Rice varieties that produce kernels that are firm and fluffy after cooking are generally favored in countries such as India, Pakistan, and Indonesia. Whereas varieties with kernels that maintain its shape, glossiness, savory odor, stickiness, and tenderness when cooked are preferred in Korea. This study analyzed the major physicochemical components of rice grain associated with the eating quality of 20 japonica rice varieties. Physicochemical components such as the amylose content, protein content, amylographic characteristics of polished rice, and texture of cooked rice were tested using a Tensipresser as alternative indirect methods in determining rice eating quality. Evaluation of eating quality of cooked rice using sensory test was conducted with 20 well trained members. The 20 rice varieties in different eating quality showed amylose contents of 17~20%. The amylose content of rice varieties had negative correlation with peak viscosity, however positive correlation with setback viscosity was observed. The stickiness and adhesiveness of cooked rice showed correlation with the amylose content and amylopectin chain length distribution. Rice varieties with good eating quality showed less retrogradation of cooked rice and higher hot viscosity of rice flour in amylogram.

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Relationship between rice grain quality traits and starch pasting properties using early maturing rice cultivars in Chungnam plain area

  • Yun, Yeo-Tae;Chung, Chong-Tae;Lee, Jae-Chul;Lee, Young-Ju;Na, Han-Jung;Lee, Kwang-Won;Yoon, Young-Hwan
    • Korean Journal of Agricultural Science
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    • v.42 no.3
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    • pp.151-158
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    • 2015
  • This study was conducted to know the variation and relationship of rice grain quality and starch pasting properties by transplanting times. Two early maturing rice cultivars which accounted for the most area of early maturing rice cultivar in Chungnam province were used. The experiment was laid out in a split-plot design with 3 replications. The main plot consisted of three transplanting times viz. early (April 25), ordinary (May 25) and late (June 25) with sub-plots containing two cultivars. According to the transplanting times, most of rice grain quality and starch pasting properties showed significant difference and Joami showed higher grain quality than Unkwang in all transplanting times. Especially, rice grain quality was improved when transplanted late, showing high head rice and glossiness of cooked rice due to the lower mean temperature during grain filling stage. Glossiness of cooked rice was positively correlated with head rice ratio, amylose content and setback value, and negatively correlated with chalky rice ratio and protein content. The highest positive and negative correlation were observed between breakdown value and peak viscosity ($r=0.98^{**}$), and breakdown and setback ($r=-0.94^{**}$), respectively. These results provide some information for rice researchers and producers producing cultivars with an improved quality, suggesting that rice quality is highly influenced by temperature at grain filling stage, and transplanting times is crucial in improving rice quality. In addition, starch pasting properties are useful for determining rice quality because rice grain quality and starch pasting properties are dependent on each other.

Changes in Palatability of Cooked Rice by Blending High Quality Rice or Glutinous Rice to Low Quality Rice and by Blending Rice of Different Varieties (불량식미쌀에 대한 우량식미쌀 및 찹쌀의 혼합과 쌀의 품종간 혼합이 밥맛에 미치는 영향)

  • Yong-Woong Kwon;Je-Cheon Chae;Jeon-Woo Bang
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.36 no.4
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    • pp.351-359
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    • 1991
  • Demand for the rice of better eating quality is ever increasing in recent years. However. the rice is presently handled by the government and merchants as mixture of the rice of different varieties from the purchase of the rough rice to storing and milling. It is well known that the eating quality of rice varies significantly by variety. The present study aimed at evaluation of the effect of blending different rices on the change in palatability of low and high eating quality rices. The eating quality of a low quality japonica rice was improved significantly on sensory panel test by blending it with the Dongjin rice. one of the highest eating quality. only when the Dongjin was blended to 80 percent by weight. and also it was same for blending an ordinary quality rice of mixed varieties which has been stored by a governmental storehouse with a top class rice on free market. The eating quality of aged Tongil type rice. produce of 1987 and 1989 and a mixture of varieties, was improved significantly by blending it with a high quality glutinous rice on market to 20 per cent by weight. But Samgang rice. a high eating quality Tongil type variety. and an ordinary quality rice of Japonica varieties were not significantly improved by blending them with the glutinous rice by 20 per cent. Blending rices of the variety Nagdong. ordinary quality among varieties and low quality among Japonicas, Chucheong, a high quality rice among Japonicas. and Dongjin. one of the best eating quality rice among Japonicas, each other in different ratios did not affect significantly the sensory scores.

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Changes in the Grain Quality of Rice with Respect to the Duration of Lodging Time

  • Hwang, Tai-Jeong;Lee, Won-Jong;Shin, Jin-Chul;Lee, Chul-Won;Kim, Suk-Shin
    • Food Science and Biotechnology
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    • v.18 no.6
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    • pp.1459-1463
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    • 2009
  • The specific objective of this study was to determine the changes in grain quality of lodged rice with respect to the duration of lodging time and compare the changes with those of unlodged one. The rice 'Janganbyeo' was cultivated and half of paddy field was totally lodged at 30 days after heading. Both lodged paddy and unlodged paddy were harvested at intervals and used for the grain quality determination. The lodged rice did not show any remarkable changes in grain quality until the $4^{th}$ day of lodging for rough rice and until the $2^{nd}$ or the $4^{th}$ day of lodging for brown rice and white rice. The overall grain quality of lodged rice could be kept for 2 to 4 days of lodging.

Survey study on the quantity cookery of steamed rice. (많은 양의 밥짓기에 대한 실태조사)

  • 이혜수
    • Journal of the Korean Home Economics Association
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    • v.8 no.1
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    • pp.93-99
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    • 1970
  • To Know the factors required to make best quality of steamed rice with large amount of rice, several organizations that serve meals were surveyed. Factor that mostly influence the amount of water to the amount of rice is a kind or rice. In the case of good quality rice, when the amount of rice is more than 10cups, the ratio of water to rice is 0.9 and that of poor quality rice is 0.7 Average ratio is 0.8 Therefore, ordinarily with the ratio of 0.8, good quality of steamed rice can be made. Washed rice should be used to measured the of rice. To make a good quality of steamed rice with large amount of rice, center part of the boiling rice should be stirred generously several times to equalize the temperature.

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Post-harvest Technology for High Quality Rice in Japan

  • Ohtsubo, Kenichi
    • Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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    • pp.26-32
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    • 2003
  • Rice is one of the most important cereals in the world. Japanese people use about 9 million tons of rice per you. We use rice for cooked rice as staple foods and for processing, such as rice wine (sake), rice crackers and miso fermentation, etc. Palatability, eating quality, of rice is evaluated by the sensory test and various kinds of physicochemical measurements. Japanese National Food Agency started the storage of 1.5 million tones of rice in 1996. We carried out the storage test using high quality rices since 1995 until 1996. As indices for the quality deteriorations of rice grains during the storage, germination ratio, enzyme activities, fat acidity, physical properties of cooked rice were clarified to be useful. We applied colorimetric method for the measurements of fat acidities in the place of titration method. Processing suitabilities of rice differ depending on the products. Low amylose rice is more suitable for soft rice crackers and high amylose rice is preferred more for rice noodle. Pre-cooked rice products, such as frozen cooked rice, retort-pouched rice and aseptic rice, are increasing recently in Japan. In addition to above-mentioned physico-chemical tests, NIR spectroscopy,“Midometer”and“Taste sensor”are novel and useful to evaluate eating quality and processing suitabolities. Recently, rice wholesalers and retailers have been obligated to display the name of cultivar, location of cultivation and the year of production of rice grains which they sell by the Japanese Agricultural Standard Law (JAS). In order to detect the dishonest labeling of rice cultivars, we developed new cultivar identification method based on DNA polymorphism.

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Quality evaluation of local brand rice in rice exporting countries

  • Kwak, Kang Su;Yoon, Mi Ra;Cho, Young Chan;Lee, Choon Ki;Choi, In Duck;Kim, Mi Jung;Kim, Sun Lim;Kim, Wook Han
    • Proceedings of the Korean Society of Crop Science Conference
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    • pp.254-254
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    • 2017
  • This study evaluated the grain quality of local brand rice from 6 major rice exporting countries which are anticipated to export their rice to Korea. Recently, with the end of the postponement of rice import tariffs in 2014, Korea is in a very easy environment to import foreign rice. Therefore, the quality evaluation of local brand rice in those countries is needed to secure the quality competitiveness of Korean rice, also to protect the rice industry in Korea. We provided total 38 local brand rice from USA(7), China(16), Australia(4), Thailand(3), Vietnam(5) and India(3), and 2 imported brand rice through MMA from USA and China to find out the status of the grain quality for each country. For the quality evaluation, we analyzed the physicochemical properties, milling and palatability-related characteristics. The amylose content on country average ranged from 24.4(India)~16.2%(Thailand). The protein content was 6.66% by overall average, and was higher in order of India(7.86), Australia(6.80), Vietnam(6.61), Thailand(6.59), China(6.28), USA(5.82). In Toyo glossiness value, it ranged from 75.7~45.2, and the figures in USA and China were the highest level. The head rice ratio ranged from 95.2~72.4%, and the figures in Thailand, USA and China were distinctly high. When we analyze the palatability of boiled brand rice with Chucheongbyeo as check variety by expert panelists, several rice brands from USA and China showed equal or better scores in shape, smell, taste, stickiness, texture and overall score, although most rice brands showed a tendency to decrease significantly in the taste characteristics compared with Chucheongbyeo. From the above results, it can be seen that the grain quality of USA and China rice is very competitive when imported into Korea. The results will provide basic information for the quality control of foreign rice which will be imported into Korea in the near future, also for the quality information which could be applied on the development of high-quality Korean rice varieties. Continuous monitoring about the foreign brand rice is advisable to improve the quality competitiveness of Korean rice.

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Physicochemical Characteristics and Varietal Improvement Related to Palatability of Cooked Rice or Suitability to Food Processing in Rice (쌀 식미 및 가공적성에 관련된 이화학적 특성)

  • 최해춘
    • Proceedings of the Korean Journal of Food and Nutrition Conference
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    • pp.39-74
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    • 2001
  • The endeavors enhancing the grain quality of high-yielding japonica rice were steadily continued during 1980s∼1990s along with the self-sufficiency of rice production and the increasing demands of high-quality rices. During this time, considerably great, progress and success was obtained in development of high-quality japonica cultivars and qualify evaluation techniques including the elucidation of interrelationship between the physicochemical properties of rice grain and the physical or palatability components of cooked rice. In 1990s, some high-quality japonica rice caltivars and special rices adaptable for food processing such as large kernel, chalky endosperm aromatic and colored rices were developed and its objective preference and utility was also examined by a palatability meter, rapid-visco analyzer and texture analyzer. The water uptake rate and the maximum water absorption ratio showed significantly negative correlations with the K/Mg ratio and alkali digestion value(ADV) of milled rice. The rice materials showing the higher amount of hot water absorption exhibited the larger volume expansion of cooked rice. The harder rices with lower moisture content revealed the higher rate of water uptake at twenty minutes after soaking and the higher ratio of maximum water uptake under the room temperature condition. These water uptake characteristics were not associated with the protein and amylose contents of milled rice and the palatability of cooked rice. The water/rice ratio (in w/w basis) for optimum cooking was averaged to 1.52 in dry milled rices (12% wet basis) with varietal range from 1.45 to 1.61 and the expansion ratio of milled rice after proper boiling was average to 2.63(in v/v basis). The major physicochemical components of rice grain associated with the palatability of cooked rice were examined using japonica rice materials showing narrow varietal variation in grain size and shape, alkali digestibility, gel consistency, amylose and protein contents, but considerable difference in appearance and torture of cooked rice. The glossiness or gross palatability score of cooked rice were closely associated with the peak. hot paste and consistency viscosities of viscogram with year difference. The high-quality rice variety “Ilpumbyeo” showed less portion of amylose on the outer layer of milled rice grain and less and slower change in iodine blue value of extracted paste during twenty minutes of boiling. This highly palatable rice also exhibited very fine net structure in outer layer and fine-spongy and well-swollen shape of gelatinized starch granules in inner layer and core of cooked rice kernel compared with the poor palatable rice through image of scanning electronic mcroscope. Gross sensory score of cooked rice could be estimated by multiple linear regression formula, deduced from relationship between rice quality components mentioned above and eating quality of cooked rice, with high Probability of determination. The ${\alpha}$ -amylose-iodine method was adopted for checking the varietal difference in retrogradation of cooked rice. The rice cultivars revealing the relatively slow retrogradation in aged cooked rice were Ilpumbyeo, Chucheongbyeo, Sasanishiki, Jinbubyeo and Koshihikari. A Tongil-type rice, Taebaegbyeo, and a japonica cultivar, Seomjinbyeo, shelved the relatively fast deterioration of cooked rice. Generally, the better rice cultivars in eating quality of cooked rice showed less retrogiadation and much sponginess in cooled cooked rice. Also, the rice varieties exhibiting less retrogradation in cooled cooked rice revealed higher hot viscosity and lower cool viscosity of rice flour in amylogram. The sponginess of cooled cooked rice was closely associated with magnesium content and volume expansion of cooked rice. The hardness-changed ratio of cooked rice by cooling was negatively correlated with solids amount extracted during boiling and volume expansion of cooked rice. The major physicochemical properties of rice grain closely related to the palatability of cooked rice may be directly or indirectly associated with the retrogradation characteristics of cooked rice. The softer gel consistency and lower amylose content in milled rice revealed the higher ratio of popped rice and larger bulk density of popping. The stronger hardness of rice grain showed relatively higher ratio of popping and the more chalky or less translucent rice exhibited the lower ratio of intact popped brown rice. The potassium and magnesium contents of milled rice were negatively associated with gross score of noodle making mixed with wheat flour in half and the better rice for noodle making revealed relatively less amount of solid extraction during boiling. The more volume expansion of batters for making brown rice bread resulted the better loaf formation and more springiness in rice bread. The higher protein rices produced relatively the more moist white rice bread. The springiness of rice bread was also significantly correlated with high amylose content and hard gel consistency. The completely chalky and large gram rices showed better suitability for fermentation and brewing. Our breeding efforts on rice quality improvement for the future should focus on enhancement of palatability of cooked rice and marketing qualify as well as the diversification in morphological and physicochemical characteristics of rice grain for various value-added rice food processings.

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Trend and Prospect of Rice Quality Evaluation (쌀의 품질평가 현황과 전망)

  • Kim Jae-Hyun;Lee Jung-Il;Youn Young-Hwan;Kim Je-Kyu;Hwang Hung-Goo;Moon Hun-Pal;Son Jong-Rok
    • Proceedings of the Korean Society of Crop Science Conference
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    • pp.53-57
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    • 2002
  • Quality evaluation must be more developed in order to offer the sufficient information for producer, distribution centers buyer, consumer. There are many parameters which influence the rice quality and cooked rice. It is difficult to evaluate the quality of rice and cooked rice by only some parameters. In the case of rice quality evaluation in Korea, physicochemical inspection is performed by examining the minimum and maximum limits of brown rice recovery, moisture content, damaged kernel, and colored kernel as inspection standard. Marketing standard of rice defines the limits of perfect, white core and belly, colored, damaged kernels, and broken rice, classifying into special, excellent, and normal grades. As a research direction for the development of rice quality evaluation, establishment as parts of technical field, must be further developed as follows : more detailed measure of characters, search of unknown taste-related components, creation and grade classification of quality evaluation factors at each management stages of treatment after harvesting, evaluation as food material as well as cooking rice, method development for simple evaluation and establishment of equation for palatability. In the side of policy, the following concerns must be conducted: price discrimination in conformity to rice cultivar and grade under the basis of qualify evaluation method developed, fixation of head rice branding, and introduction of low temperature circulation.

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Effect of Thawing Methods and Storage Periods on the Quality of Frozen Cooked Rice

  • Oh, Myung-Suk
    • Preventive Nutrition and Food Science
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    • v.3 no.3
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    • pp.234-240
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    • 1998
  • This study attempted to determine the effect of various thawing methods and storage periods on the quality of froen cooked rice. Frozen cooked rice was thawed at four different methods, such as pressure cooking, conventional cooking, microwave heating and thawing at room temperature after 10 days, 30days and 90 days frozen storage. We conducted a physico-chemical analysis (moisture content, dehydration rates, degree of gelatinization, color value and texture) and sensory evalution on the frozen-thawed cooked rice. The study showed that there were no significant differences on the quality characteristics of frozen-thawed cooked rice during the storage period of 90 days. However, the thawing method of pressure cooking caused high moisture content, rapid dehydration rates, and a high degree of gelatinization on the cooked rice. Thus, the desirabililty for the rice diminished becaused of the excess moisture content and the change of appearance and testure in the rice due to the high temperature. There were similiar quality characteristics to the cooked rice after forzen-thawing whether by conventional cooking or by microwave heating and just after cooking. Thawing at room temperature also caused a significant decrease in quality characteristics.

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