• Food Science and Preservation
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• v.30 no.3
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• pp.472-482
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• 2023

This study used gas chromatography combined with the microelectron capture detection method to determine the most effective washing and cooking methods for removing isoprothiolane from rice. The initial isoprothiolane concentrations in brown and polished rice, before washing, were 17.03 mg/kg and 1.67 mg/kg, respectively. Residual concentrations declined with more washing cycles (19.3-59.3% for brown rice; 43.1-66.5% for polished rice); and by increasing the temperature of the washing water from 5℃ to 40℃ (56.6-63.1% for brown rice; 67.1-74.9% for polished rice). Hand-washing samples using gentle stirring or harsh rubbing reduced pesticide concentrations by 63.1-71.6% for brown rice, versus 75.4-87.4% for polished rice. Reduction in isoprothiolane concentrations varied based on the rice cooker type and whether the rice was pre-soaked. Immediate cooking using an electric- or pressure-cooker showed 78.5% and 78.4% reduction in brown rice, compared with 94.0% and 94.0% for polished rice, respectively. Pre-cooking immersion for 30 min showed similar reductions of 83.4% and 83.4% in brown rice, versus 95.8% and 95.8% in polished rice. The results of this study suggest that the most effective method for removing residual isoprothiolane from both brown rice and polished rice was to wash six times (with vigorous rubbing during the 2nd and 3rd washing) in 7-fold water at 40℃, followed by immersion for 30 min before cooking. Regardless of the type of rice cooker, heating is sufficient to remove an average of 83.4% and 95.8% of isoprothiolane from brown rice and polished rice, respectively.

• Journal of Nutrition and Health
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• v.6 no.3
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• pp.9-15
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• 1973

Some effect on the protein metabolism in growing albino rats by feeding on the rice mixed with wheat or barley have been studied. The species of wheat and barley used in this experiment were either 80% polished or nonpolished wheat, barley and naked barley. The growing rats to be examined were fed on 30% wheat or barley mixed with rice diets for 8 weeks. The total nitrogen, creatinine, amino acid nitrogen and urea-nitrogen contents in the liver and the creatinine and urea-nitrogen contents in the urine have been measured. The results obtained are summarized as follows: 1. The total nitrogen contents in the liver and the serum were no remarkable difference by feeding on each mixed diet, compared with the rice diet group. 2. The creatinine contents in the liver of the unpolished wheat and barley mixed diet groups were the similar to that of the rice diet group, but these were higher by feeding on the polished wheat and barley mixed with rice diets. 3. The amino acid nitrogen contents in the liver of the polished naked barley mixed with rice diet groups were the similar to that of the rice diet group, but these were higher by feeding on the other mixed diets than the rice diet. 4. The urea-nitrogen contents in the serum of the polished wheat and naked barley mixed with rice diet groups were higher than that of the rice diet group, but these were significantly lower by feeding on the polished barley mixed with rice diets than the others. 5. The creatinine and the urea-nitrogen contents in the urine of the original wheat and barley mixed with rice diet groups were higher than that of the polished wheat and barley mixed with rice diet groups. In the view of the above results, it could be seen that the protein metabolism was remarkable change according to polish of the wheat and barley.

• Preventive Nutrition and Food Science
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• v.5 no.2
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• pp.93-99
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• 2000

A study was performed to establish the detection method of irradiated cereals. A drastic reduction of the apparent viscosity of suspensions with heat treatment was observed up to 1∼2 kGy in brown rice, Job's-tears, polished barley and polished rice. They were gently reduced to samples irradiated at 15 kGy. This trend was similar for all stirring speeds. The viscosity of unirradiated brown rice, Job's-tears, polished barley and polished rice reduced with in-creasing stirring speeds and this tendency was similar for irradiation doses. Regression expressions and coefficients of brown rice, Job's s-tears, polished barley and polished rice on different doses were 0.9399($y=3408.0e^{-0.2338x}$), 0.8855($y=3597.8e^{-0.6864x}$), 0.9343($y=7554.0e^{-0.4998x}$) and 0.9714($y=3228.2e^{-0.5312x}$), respectively, at 120 rpm. These results sug-gest that detection of irradiation for cereals could be possible by viscometric methods.

• Analytical Science and Technology
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• v.37 no.1
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• pp.12-24
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• 2024

In this study, laser-induced breakdown spectroscopy (LIBS) was used to estimate the degree of rice polishing. As-threshed rice seeds were dehusked and polished for different times, and the resulting grains were analyzed using LIBS. Various atomic, ionic, and molecular emissions were identified in the LIBS spectra. Their correlation with the amount of polished-off matter was investigated. Na I and Rb I emission line intensities showed linear sensitivity in the widest range of polished-off-matter amount. Thus, univariate models based on those lines were developed to predict the weight percent of polished-off matter and showed 3-5 % accuracy performances. Partial least squares-regression (PLS-R) was also applied to develop a multivariate model using Si I, Mg I, Ca I, Na I, K I, and Rb I emission lines. It outperformed the univariate models in prediction accuracy (2 %). Our results suggest that LIBS can be a reliable tool for authenticating the degree of rice polishing, which is closed related to nutrition, shelf life, appearance, and commercial value of rice products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.1
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• pp.152-157
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• 2004

Physicochemical characteristics of rice milled by newly designed abrasive milling machine were studied. Crude protein and crude lipid contents were 7.81∼8.50% and 1.07∼0.95%, respectively, and they showed a tendency to decrease with milling times. However, they showed higher values than that of polished rice. Major fatty acids of crude lipid were palmitic acid, oleic acid, and linoleic acid. Whiteness of tested samples was higher than brown rice but lower than polished rice. The remain rate of rice germ of four pass-through and polished one time sample (FPS) was 39.33%, and it was higher than that of polished rice (4.00%). One thousand grain weight of samples over than three pass-through was significantly different from brown rice (p<0.05). FPS had smooth surface similar to polished rice and it showed some residual rice germ by scanning electron microscopy. Sensory evaluation showed that the taste of three pass-through rice, four pass-through rice, and FPS was not significantly different from polished rice, whereas their color, odor, texture, and overall acceptability had lower score than polished rice but higher than brown rice. Therefore, we estimate that rice ground over three pass-through by newly designed abrasive milling machine might be a good source having nutritive value.

• Korean Journal of Environmental Agriculture
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• v.28 no.2
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• pp.131-138
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• 2009

Heavy metal residues in soil, rice straw, unhulled rice, rice hull, polished rice, and rice barn on the rice paddy in the "Top rice production complex which is non-contaminated area were evaluated. It was observed that the average concentrations of As, Cd, Cu, Pb, and Hg in the paddy soils were 1.235, 0.094, 4.412, 4.728 and 0.0279 mg/kg, respectively. There were no cultivation areas exceeded of the threshold for soil contamination designated by "The Soil Environment Conservation Law" in Korea. For the polished rice, there were no samples exceeded of a permissible level of heavy metal residues such as 0.051 mg/kg of As, 0.040 mg/kg of Cd, 0.345 mg/kg of Cu, 0.065 mg/kg of Pb and 0.0015 mg/kg of Hg. For the uptake and translocation of heavy metals to rice plant, a main part of heavy metal accumulation was rice straw, and then rice bran. Furthermore, it shown that accumulation of heavy metals in unhulled rice, rice hulls, brown rice, and polished rice was approximately similar as low. The slopes of translocation of heavy metals from soil to polished rice were following order as Cd, 0.4321 > Cu, 0.054 ${\fallingdotseq}$ Hg, 0.052 > As, 0.021 > Pb, 0.008. It was observed that potential ability of Cd uptake in rice plant and then its translocation into polished rice was very high. Concentrations of copper and mercury absorbed in the rice plant were moderate for translocating into the polished rice, while the arsenic and lead in the plant were scarcely translocated into the polished rice. The distribution of heavy metals absorbed and translocated into aboveground parts of rice plant was appeared that there were remained at 63.3-93.4% in rice straw, 6.6-36.9% in unhulled rice, 0.6-5.7% in rice hulls, 3.2-31.3% in brown rice, 0.8-4.6% in rice bran and 1.1-26.7% in polished rice. The accumulation ratio of Cd in the aboveground parts of rice plant was remained at 26.7-31.3% in brown and polished rice.

• Korean Journal of Food Science and Technology
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• v.11 no.1
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• pp.18-25
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• 1979

In order to investigate the effect of polishing washing and cooking processes on the residue level of BHC in rice grain, brown rice samples having a 0.3 ppm total BHC content were subjected to various treatments and residue analysis. The results are summarized as follows: 1) The conventional polishing process of brown rice decreased the residue level down to 8 and 20% for 100 and 70% polished rice, respectively. 2) The washing procedure decreased the level to 34 and 31% for 100 and 70% polished rice, respectively. 3) The cooking processes with a conventional kettle and an automatic electric cooker decreased the residue level to 86 and 77% in 100% polished rice, and 69 and 41% in 70% polished rice, respectively. 4) By summation of the above results in sequence. it was concluded that the residue levels of BHC in cooked rice were 2.3 and 4.3% of original residue in the brown rice for 100 and 70% polished rice, respectively.

• Journal of Applied Biological Chemistry
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• v.61 no.4
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• pp.391-395
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• 2018

There is an increasing concern over arsenic (As) contamination of paddy soil and rice with regard to food safety. This study was conducted to investigate total and inorganic As concentration in one hundred husked and polished rice samples collected at the non-contaminated paddy soil in Korea. Arsenic species in rice samples were extracted using 1% nitric acid ($HNO_3$) with a microwave oven and were measured using high performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry. Mean concentrations of total As in husked rice and polished rice were 0.18 and $0.11mg\;kg^{-1}$, respectively. Also, average inorganic As concentrations in husked rice and polished rice were 0.11 and $0.07mg\;kg^{-1}$, respectively. These levels are lower than the standard guideline value 0.35 and $0.2mg\;kg^{-1}$ for inorganic As in husked and polished rice recommended by Codex Committee on Contaminants in Foods and Ministry of Food and Drug Safety, respectively. The mean of the inorganic As ratio for the total amount of As was 0.65 and 0.67 for husked rice and polished rice, respectively, and the range was from 0.08 to 1.0. For health risk assessment, the average value of cancer risk probability was $9.24{\times}10^{-5}$ and ranged from $2.30{\times}10^{-5}$ to $1.90{\times}10^{-5}$. Therefore, human exposure to As through dietary intake of surveyed rice samples might considered to be a low health risk.

• Journal of Food Hygiene and Safety
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• v.23 no.1
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• pp.6-14
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• 2008

Objective of this study was to investigate the residual levels of mercury (Hg) in soil for "Top-rice" area and its uptake into rice plant for making sure food safety as compared to "Top-rice" & common rice produced from 2005 to 2006. Hg was analyzed with the direct mercury analyzer (DMA 80, Milestone, Italy), which implements the US/EPA method 7473. The average concentration of Hg in paddy soil was 0.031 mg/kg, which was below at 1/25-1/65 fold of the threshold levels (concern level 4 mg/kg, action level 10 mg/kg) for soil contamination designated by "The Soil Environment Conservation Law" in Korea. The maximum residue level (MRLs) for Hg residue in the polished rice is not designated in Korea. Therefore, Hg contents in the polished rice of "Top-rice" brand and common rice were compared to other country's criteria. Hg contents in the polished rice of "Top-rice" brand was 0.0018 mg/kg, which was lower at 1/10-1/30 fold than the MRLs, 0.02 mg/kg of China criteria and 0.05 mg/kg of Taiwan criteria, respectively. Hg were 0.02788, 0.00896, 0.00182, 0.00189, 0.00166, 0.00452 and 0.00145 mg/kg in soil, rice straw, unhulled rice, rice hulls, brown rice, rice bran, and polished rice produced in 2006 "Top-rice" area, respectively. For the ratio of Hg as compared to Hg contents in soil, there were 0.321 of rice straw ${\gg}$ 0.162 of rice bran ${\gg}$ 0.068 of rice hulls > 0.065 of unhulled rice > 0.060 of brown rice> 0.052 of polished rice. And, the slope of Hg uptakes was steeped as following order; rice straw ${\gg}$ rice bran ${\gg}$ rice hulls > unhulled rice > brown rice > polished rice. It means that the more slope steeped was the more uptakes. For the distribution of Hg uptaken, there was 83.8% into rice straw, and 16.2% into unhulled rice, 2.8% into rice hulls, 12.4% into brown rice, 3.5% into rice bran and 9.7% into polished rice. Consequently, it was appeared that the Hg contamination in the polished rice should not be worried in Korea.

• Korean Journal of Environmental Agriculture
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• v.38 no.2
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• pp.96-103
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• 2019

BACKGROUND: This study was conducted to develop selenium (Se)- and germanium (Ge)-enriched rice by foliar spray application of organic or inorganic Se and Ge. METHODS AND RESULTS: The time and frequency of organic or inorganic Se and Ge treatment were performed at the five main growth stages as followings: effective tillering stage (E), maximum tillering stage (M), booting stage (B), heading stage (H), grain filling stage (G). The main treatment plots were consisted of (1) 'once' treatment (at each E, M, B, H, G stage, Se/Ge single apply), (2) 'twice I' (at H + G stages, organic or inorganic Se/Ge apply), (3) 'twice II' (at H + G stages, mixture apply of Se + Ge + pesticide). The organic or inorganic Se treatment concentration was 20 and 40 ppm, and the Ge was 50 and 100 ppm. The Se and Ge contents in rice grain (brown rice and polished rice) were analyzed by inductively coupled plasma (ICP). The highest Se content was noted in brown rice 'twice I' with Se 40 ppm (1394.06) at H + G stages, but the lowest was in 'once' with Se 40 ppm ($367.79{\mu}g{\cdot}kg^{-1}$) at B stage. The highest of Se content in polished rice was found in 'twice I' of Se 40 ppm (1090.25) at H + G stages, but the lowest was in 'once' with Se 40 ppm ($403.53{\mu}g{\cdot}kg^{-1}$) at E stage. On the other hand, The highest of Ge content in brown rice was found in 'twice I' with Ge 100 ppm (398.66) at H + G stages, but the lowest was in 'once' with Ge 100 ppm ($139.64{\mu}g{\cdot}kg^{-1}$) at B stage. The highest of Ge content in polished rice was found in 'twice I' of Ge 100 ppm (300.29) at H + G stages, but the lowest was in 'once' with Ge 100 ppm ($142.24{\mu}g{\cdot}kg^{-1}$) at B stage. CONCLUSION: Se and Ge contents both in brown rice and polished rice treated with organic Se and Ge forms were higher than those of inorganic Se and Ge. Overall results concluded that the supplementation of organic Se and Ge contents in brown and polished rice contents were comparatively higher than the inorganic Se and Ge. This is results also proved that the foliar spray application of organic Se and Ge has positive nutritive effect on the rice for regular consumption.