• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.325-325
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• 2022

In order to developing high-quality rice varieties and processing varieties, systematic and stable evaluation of physicochemical properties is required for breeding lines. In this study, we compared the quality characteristics evaluation results of rice breeding lines for cooked rice, special rice, and whole crop silage rice adapted to central plain region (Suwon) in order to use as basic data for future rice variety development. Brown rice length/width ratio, head rice ratio, protein content, amylose content, alkali digestion value(ADV) and Toyo value were analyzed to evaluate the quality characteristics of yield trial lines cultivated in Suwon for four years (2017-2020). Brown rice length/width ratio, head rice ratio, protein content, ADV and Toyo values showed significant differences by year, but there was no significant difference in amylose content (p<0.05), which showed little environmental variation. The head rice ratio and Toyo value showed an increasing trend, while the protein content showed a decreasing trend. However, the protein content was the highest in 2020, which is thought to be owing to little sunlight hours due to heavy rainfall in 2020. The protein content of whole crop silage rice was 8.1%, which was significantly higher than that of other lines (p<0.05). Toyo value of medium-maturing and early-maturing lines were 67.6 and 73.7%, respectively, and the Toyo value of medium-maturing lines was higher than that of the early-maturing lines (p<0.05). In correlation analysis among the quality characteristics of the rice lines for cooked rice, significant positive correlations were detected between Toyo value and head rice ratio, amylose content, ADV, and a negative correlation was observed between Toyo value and protein content (p<0.05).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.1
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• pp.1-6
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• 2012

In this study, we conducted to identify predictive parameters affecting the head rice ratio for developing high quality rice cultivar adaptable to the early-transplanting cultivation. The recombinant inbred lines (RILs) population from a cross between the parents of Pungmi and Koshihikari was used for test materials. Variations were observed in most of the measurements, eg culm length (ranging from 51.0 cm to 97.0 cm), amylose content (14.0~20.1%), protein content (5.2~7.4%), pasting properties (peak viscosity, 227.2~309.8 RVU) and head rice ratio (67.7~96.7%). Significant correlations between head rice ratio versus culm length (0.443) and head rice ratio versus protein content (-0.458) were detected in RIL population. However, culm length was negatively related to lodging tolerance. In order to develop a commercially suitable cultivar, selection for short culm and high head rice ratio of rice grains with physiochemical properties such as protein content, amylase content and taste value should be considered. This results can be used to increase the efficiency of breeding program for developing a new early-maturing rice variety adaptable to early transplanting cultivation in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.2
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• pp.79-86
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• 2017

This study was conducted to analyze seasonal and annual variations in rice quality and factors affecting the quality, for quality evaluation of the brand rice varieties produced in Jeonnam region. Coefficient of variation (CV) values for the seasonal variation in the rice quality were 3.1% in Toyo value, 2.1% in whiteness, 1.6% in protein content, 1.0% in moisture content, and 0.4% in head rice ratio. Quality characteristics of the brand rice varieties generally showed a decreasing tendency after April, as the months progressed. CV values for the annual variation in the rice quality were relatively high at 5.6% in protein content and 5.2% in Toyo value whereas those for whiteness and head rice ratio were relatively low, at 2.7% and 1.8%, respectively. Palatability and protein content showed high correlations with minimum air temperature, sunshine hours, rainfall, and daily temperature range. Head rice ratio had a negative correlation with daily temperature range whereas chalky rice ratio had a positive correlation with rainfall. Based on these results, we formulated a multiple regression equation to estimate palatability of cooked rice using protein content, whiteness, head rice ratio, and moisture content as follows: y = - 6.71a + 2.27b + 1.29c + 0.51d - 15.34 ($R^2$=0.51*) (y: palatability of cooked rice, a: protein content, b: moisture content, c: whiteness, d: head rice ratio).

• The Korean Journal of Food And Nutrition
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• v.29 no.5
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• pp.605-609
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• 2016

This study aimed to find the optimum instrumental test conditions for the Texture Profile Analysis (TPA) of cooked rice in order to predict the sensory texture attributes (hardness, adhesiveness, chewiness). Sensory evaluation was performed for three kinds of instant cooked rice with university students in their twenties and the results of the sensory evaluation were compared to instrumental TPA patterns. Using partial least squares regression, the instrumental TPA results at a cross-head speed of 1.0 mm/sec and a compression ratio of 70% proved to be an excellent predictor of the sensory attributes of hardness ($R^2=0.99$) and chewiness ($R^2=0.99$). The results at a cross-head speed of 0.5 mm/sec and compression ratio of 30% provided an excellent model for the prediction of sensory adhesiveness ($R^2=0.83$). In this experimental range, sensory hardness and chewiness showed a high correlation with instrumental TPA parameters (hardness, cohesiveness, adhesiveness, springiness, chewiness) with a high cross-head speed and compression ratio, while sensory adhesiveness showed a high correlation with the TPA parameters with a low cross-head speed and compression ratio.

• Korean journal of food and cookery science
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• v.25 no.2
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• pp.260-265
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• 2009

The influence of mixing ratio of 25 commercial rice varieties was evaluated by DNA analysis and Toyo value palatability. No relationship was evident between rice palatability and various grain quality properties, or between palatability and mixing ratio. A positive relationship was evident between palatability and texture and between palatability and chalky rice ratio. A negative relationship was evident between mixing ratio and amylose content.

• Journal of Biosystems Engineering
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• v.13 no.4
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• pp.9-19
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• 1988

The threshing of head-feed combine may be accomplished mainly by the action of impact between threshing teeth and rice. In this study, it was attempted to assess threshing performance characteristics of head-feed threshing teeth. And the characteristics of threshing teeth will be applied to the method which could analyze the time and order of impact between teeth and the rice, which was used as a basis for predicting the threshing performance and determining the optimum design parameters. The results of the study are summarized as follows: 1. About 50% of threshed material were threshed by the beginning 7 impacts on the rice bundle. Threshing torque decreased until 25 impacts and did not change thereafter. 2. There was significant difference in the threshability according to the shape of threshing teeth. The triangular-shaped tooth was the most efficient in threshability ratio and the semicircle-shaped tooth was the lowest. There was no significant difference in specific energy requirement for the varied teeth design. Torn-head ratio being generated by the semicircle-shaped and the triangular-shaped teeth in series was less than that by a single tooth with the triangular-shaped and the double setting of the triangular-shaped. Chaff generation ratio by the triangular-shaped and the semicircle-shaped teeth was less than the others tried. 3. The triangular-shaped teeth in series, which was newly designed for this study, showed an intermediate characteristics between the double setting of the triangular-shaped and the semicircle- shaped teeth. Threshability ratio of the triangular-shaped teeth in series was higher than that of the semicircle and lower than the double setting of the triangular-shaped tooth. Torn-head generation ratio for it was about same as that of the semicircle. Chaff being generated by the triangular-shaped teeth in series was about same as the double setting of the triangular-shaped teeth. 4. About 40% of threshed grains which passed through concave were concentrated under the threshing tooth and the rest of grains displayed a skew distribution toward the inlet of threshing chamber.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.29-32
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• 2005

This experiment aimed to estimate the effect of imperfect rice on rice palatability. Rice cultivar, Ilpumbyeo, was cultivated by direct-seeding on flooded paddy surface with 11 kg/10a nitrogen application. Palatability of harvested rice was measured by NIR spectroscope. Brown rice was divided according to their appearance namely, perfect, discolored, green-kerneled, and immature opaque with a composition ratio of $75.7\%,\;11.0\%,\;8.0\%,\;and\;5.3\%$ respectively. When the perfect brown rice was milled, the grain were composed of head, cracked, and white core & belly, at $64.7\%,\;25.3\%\;and\;10.0\%$ respectively. The milled rice of discolored brown rice had similar composition with the perfect rice. The milled green-kerneled vice, on the other hand, had $36\%$ head rice and $64\%$ white core & belly rice. The immature opaque brown rice, when milled, had $25.3\%$ white core & belly and $74.7\%$ damage & opaque rice. With the respect to grain quality, the viscosity of white core at belly rice and damaged & opaque rice was lower than that of head rice. In contrast, their protein content was a little higher than that of head rice. The palatability value of pure imperfect rice was much lower than head rice. The palatability value of damaged & opaque rice was the lowest among the imperfect rices. When mixed with head rice, the damaged & opaque rice impacted on the deterioration of vice palatability. Mixing $1\%$ each of white core at belly rice and damaged h opaque rice decreased the palatability value by $5\%$ as compared with the head rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.spc
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• pp.1-8
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• 2008

We carried out this study to analyze changes of rice grain milling properties according to the transplanting time and to identify genetic resources suitable for improving milling quality of rice in paddy field of Yeongnam area. We analyzed grain filling and milling quality of 30 rice varieties. In late transplanting (June 20), heading date was delayed for 6 days, compared to normal transplanting(June 5). The grain filling ratio (GFR), perfect kernel ratio of milled rice (PKR), and head rice recovery (HRR) were improved in late transplanting. There was no significant difference in head rice yield of two transplanting time, even though the milled rice yield in late transplanting was significantly smaller than that in normal transplanting because of the reduction of spikelet numbers per panicle. The uniformity of brown rice grain measured by selection sieve norm was improve in late transplanting. There was no significant difference of milling loss ratio between normal and late transplanting but there was a trend for a increase of milling necessary time in late transplanting. Thus, our result suggest that optimum transplanting time is June 10 to 15 to improve grain filling and milling quality and produce high head rice yield in the southern paddy plain of Yeongnam region. We selected promising 9 rice varieties which are Nampyeongbyeo, Ilmibyeo, Chucheongbyeo, Dongjinbyeo, Hopyeongbyeo, Malguemi, Chilbo, Hinohikari, and Cheongmu having high percentage of ripened grain and milling quality as genetic resources to improve milling characteristics of rice varieties. Chucheongbyeo, Dongjinbyeo, and Malguemi showed the highest grain filling ratio and Nampyeongbyeo had the highest perfect kernel ratio. Nampyeongbyeo and Ilmibyeo showed the highest head rice yield with more than 500 kg/10a.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.2
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• pp.107-112
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• 2013

The aim of this study was to test hypothesis that low sink size could mitigate deterioration of grain filling characteristics under high grain filling temperature. To achieve this aim, we selected Donganbyeo as a tolerant and Ilpumbyeo as susceptible variety to high temperature during grain filling period through screening 6 rice varieties. Then their spikelets number and the ratio of superior and inferior spikelet were compared. Grain weight and head rice ratio of Ilpumbyeo decreased significantly in high temperature. Ilpumbyeo had more spikelets than Donganbyeo. However, there was no significant difference between two varieties in the ratio of superior and inferior spikelets. So we tried to investigate the varietal difference of grain filling characteristics with removing inferior spikelets. Removing inferior spikelet in both of varieties could recover grain weight but not improve head rice ratio under high temperature. These results showed that sink/source ratio affected grain weight but didn't affect head rice ratio. Therefore, new approach was required to improve head rice ratio beyond sink/source ratio under high temperature.

• 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.