• Proceedings of the Korean Environmental Health Society Conference
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• 2002.04a
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• pp.55-56
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• 2002

Aflatoxin is a secondary fungal metabolite and is a public health hazard because it is a human carcinogenic and has many deleterious effects in men and animals. Rice is one of the better substrates for the fungus which can produce aflatoxins. This study was performed to investigate aflatoxin reduction during the cooking and processing of rice. Aflatoxin was produced by Aspergillus parasiticus ATCC 15517 on well-milled rice(Japonica type) at the level of 13.2 ppb. Cooked rice, rice cakes (baek-sol-gi, plain steamed rice bread), fermented rice (sik-hye, sweet rice beverage), and popped rice were prepared from the aflatoxin-contaminated rice. Aflatoxin content in the samples was determined by high performance liquid chromatography. The total aflatoxin level was decreased to 46.9％ in the cooked rice, 85.6％ in the rice cakes, 11.4％ in the fermented rice, and 7.6％ in the popped rice, respectively (p＜0.05). This reduction brought the level of aflatoxins down to below the Standard and Specification of Korea (10 ppb), except for the rice cakes. These results indicate that washing, steaming, fermentation, and popping of rice was helpful in reducing the aflatoxin level in the rice and the most helpful factors were high temperature & high pressure. More research is needed to understand why the preparation of rice cakes did not reduce the level of aflatoxin as much as the other cooking methods.

• Journal of Biosystems Engineering
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• v.25 no.6
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• pp.503-510
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• 2000

To improve the milling condition of brown rice a continuous type conditioning equipment was developed. To validate the performance of this machine the experimental operation was done at Sa-cheon RPC(Rice Processing Complex) using short grain rough. The initial moisture contents of brown rice were 15.0∼16.5%(w.b) and the flow rate of brown rice passing through the conditioner were 4,370kg per hour. The moisture content differences of brown rice between conditioned and non-conditioned were showed within 0.5%(w.b) This results means that the water injected to brown rice were absorbed to the surface of brown rice evenly. The moisture contents of conditioned treated milled rice were showed slightly higher than that of non-conditioned ones but it was considered that the conditioning process did not affected the weight increasing of milled rice by water supply. For initial moisture contents of 15.0∼16.5%(wb) brown rice it was found that the proper water supply rate was 0.115(cc-water)/(kg·%-brown rice) and the increments of whole rice were 2.2% compared to the non-conditioned ones. it was considered that the conditioning process did not influenced the whiteness of milled rice because the whiteness differences between conditioned and non-conditioned milled rice were negligible. About 18% of electric power which drives the abrasive type rice milling machine was saved at 0.115(cc-water)/(kg·%-brown rice) of water supply rate.

• Journal of Biosystems Engineering
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• v.29 no.2
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• pp.121-130
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• 2004

This study was carried out to develop a miller to produce white embryo rice with functional nutrients by improving the conventional vertical miller. The effects of rice moisture content and the shaft revolution speed of the miller on germ(embryo) adherence rate, whiteness, broken rice rate, and cracked rice rate were investigated. Also, the effect of the mesh size of emery stones on the germ adherence rate was investigated. The vertical prototype miller was improved with the increasement of about 42% in producing white embryo rice at proper conditions(shaft revolution speed of 900 rpm, emery stones of mesh ＃50, processing capacity of 2.3t/h, zero outlet resistance, rice moisture content of 16.2%). The results were as follows: 1. The germ adherence rate of white rice was significantly influenced by the moisture content of brown rice. The germ adherence rate of white rice decreased rapidly with the increase of the moisture content of brown rice. When brown rice with moisture content of 13.2%, 14.5%, 15.2%, 15.4% was milled by the prototype with emery stones of mesh ＃35 and shaft speed of 900(1,100) rpm, rpm adherence rate of milled rice was 76.2%(70%), 69.2%(66%), 45.9(38%), 13.0(9%), respectively. 2. The whiteness of white rice milled by the prototype with emery stones of mesh ＃35 and shaft speed of 1,100(900)rpm increased from 27(23) to about 40, respectively, as the moisture content of brown rice increased from 13.2% to 17.2%. 3. The rate of broken rice of white rice milled at 900rpm decreased by 0.6∼1.0% compared with that at 1,100rpm when the moisture content of brown rice was less than 15.2%. 4. The germ adherence rate was increased by 10.3% and 11.0%, respectively when brown rice with moisture content of 16.2% and 15.5% was milled by the prototype miller with shaft speed of 900rpm and emery stones of mesh ＃50 instead of mesh ＃35. 5. Considering the germ adherence rate, broken rice rate, and whiteness of milled rice, the proper milling conditions of the prototype miller for producing embryo rice were the moisture content of about 15%, the processing capacity of 2.3t/h and minimum outlet resistance of 0Nㆍm with shaft speed of 900rpm and emery stones of mesh ＃50.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47
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• pp.15-32
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• 2002

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 quality 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 cultivars 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, Recently, new special rices such as extremely low-amylose dull or opaque non-glutinous endosperm mutants were developed. Also, a high-lysine rice variety was developed for higher nutritional utility. 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 texture of cooked rice. The glossiness or gross palatability score of cooked rice were closely associated with the peak, hot paste and consistency viscosities of viscosities with year difference. The high-quality rice variety "IIpumbyeo" 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 microscope. 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 IIpumbyeo, Chucheongyeo, Sasanishiki, Jinbubyeo and Koshihikari. A Tonsil-type rice, Taebaegbyeo, and a japonica cultivar, Seomjinbyeo, showed the relatively fast deterioration of cooked rice. Generally, the better rice cultivars in eating quality of cooked rice showed less retrogradation 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 breed. 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 grain rices showed better suitability far fermentation and brewing. The glutinous rice were classified into nine different varietal groups based on various physicochemical and structural characteristics of endosperm. There was some close associations among these grain properties and large varietal difference in suitability to various traditional food processing. Our breeding efforts on improvement of rice quality for high palatability and processing utility or value-adding products in the future should focus on not only continuous enhancement of marketing and eating qualities but also the diversification in morphological, physicochemical and nutritional characteristics of rice grain suitable for processing various value-added rice foods.ice foods.

• Journal of Forest and Environmental Science
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• v.31 no.2
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• pp.119-125
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• 2015

This study examined the effects of rice straw steaming time and mixing ratio between rice straw and wood particle on the properties of mixed particle board from Acacia mangium Willd wood and rice straw. Rice straw and Acacia mangium Willd wood were collected in Hanoi, Vietnam. The particle board was three-layer particle board with the structural ratio of 1:3:1. The thickness, density and board size of the particle board were 18 mm, $0.7g/cm^3$, and $800{\times}800{\times}18$ (mm, including trimming), respectively. A resin mixture between commercial Urea-formaldehyde (U-F) adhesive and methylene diphenyl isocyanate (MDI) adhesive was used with a dosage of 12% for the core layer and 14% for the surface layer. In this experimental design, the steaming time for rice straw was 15, 30, 45, 60, and 75 minutes at $100^{\circ}C$. The rice straw-wood mixing ratio was 10, 20, 30, 40, and 50%. The results showed that both mixing ratio and steaming time affect the properties of the particleboard, but the mixing ratio has a stronger impact. A higher mixing ratio and a longer steaming time resulted in a better quality of particleboard. The optimal steaming time for rice straw was 46.12 minutes with the straw-wood mixing ratio of 29.85% with the following characteristics of the particle board: the modulus of rupture (MOR) of 14.64 MPa, internal bond strength (IB) of 0.382 MPa, thickness swelling (TS) of 8.83%, and board density of $0.7-0.7g/cm^3$.

• Korean journal of food and cookery science
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• v.28 no.5
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• pp.541-547
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• 2012

This study was performed to compare the processing aptitudes of the rice muffins produced from the seven rice varieties, including Goami, Goami 2, Deuraechan, Baegjinju, Seolgaeng, Haiami and Hanareum, along with the use of hydroxypropyl methylcelluloses (HPMCs) as a replacement for the egg white. The water binding capacity of rice flours was significantly higher than that of wheat flour, but its fat binding capacity was lower than that of wheat flour (p<0.05). In the viscosity of the batter, Goami and Baegjinju were lower than that of the wheat flour. There was no significant difference in the specific gravity of Seolgaeng and the batter of wheat flour. The pH of all varieties except Goami 2 was higher than batter of wheat flour(p<0.05). Haiami flour produced higher muffin volume and specific volume compared with the wheat flour muffin. The textural characteristics, the muffins produced by Haiami and Hanareum flours had significantly lower hardness than the wheat flour muffin after 30 hours. All rice varieties except Gaomi 2 showed no significant difference compared to the wheat flour muffin in color, taste and texture (p<0.05). Furthermore, flavor of muffins produced from the Seolgaeng, Haiami and Hanareum flours tested higher than the wheat flour muffin. It was concluded that the rice varieties of Seolgaeng, Goami, Haiami and Hanareum were considered to be the most suitable rice cultivars for the rice muffins.

• The Plant Pathology Journal
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• v.34 no.5
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• pp.356-366
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• 2018

The red flour beetle, Tribolium castaneum, is one of the most common and economically important pests of stored cereal products worldwide. Furthermore, these beetles can act as vectors for several fungal post-harvest diseases. In this study, we collected T. castaneum from 49 rice processing complexes (RPCs) nationwide during 2016-2017 and identified contaminating fungal species on the surface of the beetles. Five beetles from each region were placed on potato dextrose agar media or Fusarium selection media after wet processing with 100% relative humidity at $27^{\circ}C$ for one week. A total of 142 fungal isolates were thus collected. By sequence analysis of the internal transcribed spacer region, 23 fungal genera including one unidentified taxon were found to be associated with T. castaneum. The genus Aspergillus spp. (28.9%) was the most frequently present, followed by Cladosporium spp. (12.0%), Hyphopichia burtonii (9.2%), Penicillium spp. (8.5%), Mucor spp. (6.3%), Rhizopus spp. (5.6%), Cephaliophora spp. (3.5%), Alternaria alternata (2.8%) and Monascus sp. (2.8%). Less commonly identified were genera Fusarium, Nigrospora, Beauveria, Chaetomium, Coprinellus, Irpex, Lichtheimia, Trichoderma, Byssochlamys, Cochliobolus, Cunninghamella, Mortierella, Polyporales, Rhizomucor and Talaromyces. Among the isolates, two known mycotoxin-producing fungi, Aspergillus flavus and Fusarium spp. were also identified. This result is consistent with previous studies that surveyed fungal and mycotoxin contamination in rice from RPCs. Our study indicates that the storage pest, T. castaneum, would play an important role in spreading fungal contaminants and consequently increasing mycotoxin contamination in stored rice.

• Journal of Life Science
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• v.32 no.9
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• pp.698-705
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• 2022

Rice consumption in Korea is continuously decreasing; therefore, methods for reducing rice stocks are now being proposed. Increasing the consumption of rice and reduce these stocks will require that the rice processing industry be developed beyond simply using cooked rice as food. The Korean people's eating habits have also diversified recently, and the consumption of bread is increasing. Therefore, breeding a cultivar for rice flour is now necessary. Here, a line suitable for processing into rice flour was cultivated by deriving a mutant line by tissue culture of Ilpum. Mutant populations were investigated for major agricultural traits in the field, and grain characteristics and endosperm characteristics were investigated after harvest. Among the lines, line 29111 had similar agricultural characteristics to the background Ilpum, and excellent grain quality, and was selected for further analysis. The physicochemical properties that determine taste were similar or improved. However, unlike Ilpum, 29111 had a non-uniform starch structure and a characteristic powdery endosperm because large and male starch grains are evenly distributed. Therefore, 29111 was viewed as a breeding line suitable for processing and for excellent agricultural characteristics and taste. The added value can be increased by diversifying the uses of rice. The taste was improved and a method for breeding cultivars with grain characteristics for glutinous rice that would satisfy both producers and consumers was presented.

• Journal of the East Asian Society of Dietary Life
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• v.15 no.4
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• pp.413-418
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• 2005

This study was performed to develop new processing methods and products from steamed ginseng with rice wine. The brownnes, turbidity and the total ginsenoside in ginseng were examined All the values of examined premonitory materials, intermediate products, coloring matters and turbidity were increased as the steaming continued The quantity of total ginsenoside was increased when the steaming with rice wine continued in A1 - A9($1^{st}$ traditional rice wine steamed red ginseng: $A1{\~}9^{th}$ traditional rice wine steamed-red ginseng:A9). The quantity of ginsenoside-Rc, ginsenoside-Rd, ginsenoside-Re in Al were increased as the steaming continued. The quantity of ginsenoside-$Rg_2$ and ginsenoside-$Rg_3$ was increased when the number of steaming increased.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1999.12a
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• pp.371-377
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• 1999