• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.12
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• pp.2035-2041
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• 2013

The effects of Aspergillus oryzae rice koji (AO) and Asp. kawachii rice koji (AK) as enzyme preparations, on the quality characteristics of rice mash were invested in this study. The amount of AORM (Asp. oryzae rice mash) and AKRM (Asp. kawachii rice mash) were 50, 100, 200% (w/w) based on 100 g of rice. Firstly, in the titer measurement result on the ${\alpha}$-amylase and glucoamylase activities of AO and AK. On the other hand, the acid protease activity has values of 31.56 unit for AO and 849.17 unit for AK. The sugar solid of the AORM and AKRM groups significantly increased as the rice koji ratio on rice was higher, which were shown with values as high as 17.63~20.53 and 17.51~19.28, respectively. Glucose and maltose were detected for free sugar of AORM. Only glucose was found in AKRM. Citric acid, malic acid, and lactic acid were detected as the organic acid of KORM; oxalic acid, citric acid, and succinic acid were detected for AKRM, and the content increased as the rice koji ratio on rice increased (P<0.05). From the above result, rice koji with useful mold is expected to be used broadly in foods by looking at the fact that it has starch degradation ability and organic acid producibility.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.6
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• pp.823-828
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• 2012

Texture and descriptive sensory characteristics of a Korean rice cake (Karedduk) with added mixtures of fructooligosaccharide (95%) and emulsifier, Sodium Stearoyl Lactylate-90 (SSL-90), were investigated after 2 and 24 hr of storage at $5^{\circ}C$. A central composite design was used for the arrangement of treatment. Different levels of fructooligosaccharide (95%), 0, 3, 6, 9, and 12%, were added to dry rice flour. Also, different levels of emulsifier, 0, 0.3, 0.6, 0.9, and 1.2%, were added to the same dry rice flour. The texture properties analysis using a Texture Analyzer revealed that the chewiness, gumminess, and hardness were significantly different. The effect of retarding retrogradation of Korean rice cakes (Karedduk) with added mixtures of fructooligosaccharide (95%) and SSL-90 showed an increasing trend as the amount of fructooligosaccharide (95%) increased. Overall, the instrumental texture properties were highly correlated with the sensory characteristics. The results suggested that Korean rice cakes (Karedduk) with the addition of a mixture of fructooligosaccharide (95%) and SSL-90 can be made from the mixture of 9% fructooligosaccharide (95%) and 0.9% SSL-90 in order to retard starch retrogradation.

• Korean Journal of Food Science and Technology
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• v.26 no.5
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• pp.579-584
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• 1994

Near infrared reflectance(NIR) spectroscopy was used to determine the degree of retrogradation of cooked rice. Cooked rice samples were stored at $4^{\circ}C$ for 120 hours, and the degree of retrogradation was measured at every 6 hour during the storage time. Stored cooked rices were freeze-dried, milled and passed through a 100 mesh sieve. Enzymatic method using glucoamylase was used as reference method for the determination of the degree of retrogradation. Spectral differences due to retrogradation of cooked rice were observed at 1434, 1700, 1928, 2100, 2284 and 2320 nm. 32 samples of which moisture content were below 5% were used for calibration set, and 16 samples were used for validation set. High correlations were achieved between degree of retrogradation determined by conventional enzymatic method and by NIR with multiple correlation coefficient of 0.9753, and a standard error of calibration(SEC) of 3.64%. Comparable results were obtained with 3.91% of standard error of prediction(SEP), when the calibration equation was applied to independent group of samples of which moisture contents were in the range of calibration set. But when the calibration equation was applied to samples of which moisture contents were outer range of calibration set, SEP and bias were increased and correlation coefficient was decreased. The determination of degree of retrogradation was affected by sample moisture content. To determine degree of retrogradation of cooked rice by NIR using this calibration equation, it was suggested that sample moisture content should be controlled to below 5%.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.258-261
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• 1991

In order to establish the optimum drying temperature of the heated air blast-grain circulation dryer, a 2 ton scale of paddy was used in this experiment. The temperatures of heated air used were 45, 50, 55, 60, 65 and $70^{\circ}C$. Moisture content of the paddy was reduced to 15% from 24% by drying. The higher air temperature, the shorter drying time and the less fuel consumed. The portion of cracked kernels was found to be low as $3{\sim}10%\;at\;40{\sim}55^{\circ}C$, but was very high to $28{\sim}30%\;at\;60{\sim}70^{\circ}C$. The germination percent was very high as 98 and 93% at 40 and $45^{\circ}C$, but it was decreased to 86 and 30% at 50 and $70^{\circ}C$, respectively. The recovery yield of milled rice from paddy was decreased by 1.76, 2.63 and 7.52% at 60, 65 and $70^{\circ}C$, respectively, compared with 75.86% as drying at $40^{\circ}C$. The higher heated air temperature, the less head rice of milled rice was recovered, and the decreased ratio was increased $60^{\circ}C$. The higher heated air temperature, the less alkali disintergation value and gel consistency of milled rice and the more water up take, expanded vlume, total solid in residual liquid and intensity of starch iodine blue value of residual liquid, and those tendency was found clear from $60^{\circ}C$ temperature of heated air.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.262-264
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• 1991

In order to establish the optimum storage period of rice, storability of rice for 1, 2. 3 and 4 years was investigated. Fat acidity of stored rice for 1, 2, 3 and 4 years was measured to 12.4, 23.6, 30.8 and 41.1 KOHmg/100g, respectively. Reducing sugar of those was analized to 0.31, 0.41, 0.57 and 0.68%. Germination of the stored rice for 1, 2 and 3 years was 97, 93 and 85%, respectively, but that of stored for four years was very low 32%. The longer storage period the higher, the lower water uptake ratio and expanded volume and much the lower total solid in residual liquid and intensity of starch iodine blue value of residual liquid, and the worse panel scores in color, stickness, taste and smell.

• Korean Journal of Microbiology
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• v.10 no.4
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• pp.191-194
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• 1972

There were observed the host-parasite relationship between rice grains and contaminating fungi indicated by the fungal penetration degree in the tested rices. The results were as follows ; 1. The fungal penetration could be observed in the outer layer of the rices but couldn't be seen in the starch portin of the tested rices. 2. The Gram staining method was better than the PAS staining method for the observation of fungi penetration into the rices.

• The Microorganisms and Industry
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• v.25 no.1
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• pp.10-24
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• 1999

There were observed the host-parasite relationship between rice grains and contaminating fungi indicated by the fungal penetration degree in the tested rices. The results were as follows ; 1. The fungal penetration could be observed in the outer layer of the rices but couldn't be seen in the starch portin of the tested rices. 2. The Gram staining method was better than the PAS staining method for the observation of fungi penetration into the rices.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.221.2-222
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• 2003

The relative retrogradation of Jeungpyun investigated with different millimg methods of rice flour. The relative retrogradation of Jeungpyun was reduced in order that of W-C, W-P, D-M, D-J in DSC(Differential Scanning Calorimetry) method while W-C, D-M, D-J, W-P in Diastase method. In wet milling method, the relative retrogradation of Jeungpyun by Pin mill(W-P) was lower than Jeungpyun by colloid mill(W-C). In dry milling method, the relative retrogration of Jeungpyun by jet mill(D-J) was lower than Jeungpyun by micro mill(D-M). The relative retrogradation of Jeungpyun by DSC method was similar to the Diastase method. The relative retrogradation of Jeungpyun was decreased with decreasing particle size and setback value for amylogram and increasing damaged starch.

• 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.

• Food Science and Preservation
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• v.22 no.2
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• pp.174-181
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• 2015

This study investigated the physicochemical properties of three different types of rice flour prepared via dry and wet milling. The powder, soft, and hard-types of rice flour were Suwon No. 542, Suwon No. 541, and Unbong No. 30, respectively. The analysis of the proximate compositions of the different types of rice flour showed that their moisture content was 7.03~7.99%, their crude protein was 7.94~8.35%, their crude lipid was 0.71~1.49% and their crude ash was 0.25~0.82%. For the Hunter's color values, the L value was highest in the wet-milled rice flour, the a value was highest in the dry-milled rice flour, and the b value was highest in the dry-milled rice flour. All the samples showed distinctive rice starch particles in the particle analysis using scanning electron microscope. The dry-milled rice flour showed the greatest amount of irregular particles and the coarsest texture. The water absorption and water solubility indices were higher in the wet-milled soft- and hard-type rice flour. The crystallinities of the samples by X-ray diffractography were all A-type, but the crystallinity of the dry-milled hard-type rice flour was higher in diffraction degree. For the amylogram properties, the wet-milled soft-type rice flour showed the highest maximum viscosity, breakdown and setback. In the meanwhile, the dry-milled soft-type rice flour showed the highest initial pasting temperature, onset, peak, and end temperatures despite of the reverse enthalpy.