• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.765-772
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• 2004

Cooking condition of Tarakjuk (milk-rice porridge) was established based on gelatinization temperature using differential scanning calorimetry (DSC) of roasted Ilpum rice flour, which has highest enzyme-resistant starch (RS) content. Effect of cooking temperature and time on DSC characteristics, crystallity with X ray diffractogram, RS content, in vitro starch digestibility (IVSD), amino acid composition, and in vitro protein digestibility (IVPD) of Tarakjuk were determined. Tarakjuk was cooked at 50, 56.5, 64, and $69^{\circ}C$ for various durations. Rice flour ingredient used was Ilpum, previously roasted at $185^{\circ}C$ for 25 min. Tarakjuk cooked at 50 and $56.5^{\circ}C$ showed two thermal transitions between $63.7-125.2^{\circ}C$ as determined by DSC, corresponding to endotherms of starch gelatinization $(63.7-73.8^{\circ}C)$ and melting of amylose-lipid complex (AM-lipid complex, $97.7-125.2^{\circ}C$), whereas that cooked at 64 and $69^{\circ}C$ showed only AM-lipid complex melting transition between $96.9-127.6^{\circ}C$. As cooking temperature increased, RS content of Tarakjuk decreased, whereas IVSD increased. Total amino acid content was between 11,558-15,601mg/100g, depending on cooking condition used. Compared with conventionally made control, contents of essential amino acids, such as lysine and tryptophane, were higher at 50 and $56.5^{\circ}C$, and IVPD showed higher increase. Results reveal degree of gelatinization in Tarakjuk with high RS content as well as low IVSD and high IVPD, which are important from physiological and nutritional point of view, can be produced by controlling cooking condition.

• The Korean Journal of Food And Nutrition
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• v.31 no.4
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• pp.511-519
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• 2018

The baking properties of rice bread with different percentages of butter and oil in wet and dry rice flour were investigated. The moisture, damaged starch, mean diameter, pasting properties by amylogram and RVA (Rapid Visco Analyzer), as well as thermal properties by DSC (Differential Scanning Calorimetry) of wet and dry rice flour were analyzed. The specific gravity and color (L, a, b) of the dough, as well as the appearance, color (L, a, b) and texture of the rice bread with different percentages of butter and oil in wet and dry rice flour were also analyzed. As a result, the wet rice flour were composed of a noted higher content in moisture, compared to the dry rice flour (p<0.001). The wet rice flour had lower values of damaged starch, higher values of mean diameter and a higher peak viscosity than was noted in the dry rice flour (p<0.001). The wet rice flour showed a higher degree of hydration and gelatinization than was seen in the dry rice flour (p<0.001). The prevailing principle to utilize the replacement of wet rice flour with oil had a significant effect on the volume, specific volume and hardness of the rice bread (p<0.001). The hardness of the rice bread also showed a decreasing trend as the amount of the added oil was increased into the mixture. These results suggest that the replacement of wet rice flour with 5.8% oil is effective for the production of rice bread.

• Korean journal of food and cookery science
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• v.7 no.4
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• pp.71-86
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• 1991

This study was attempted to enhance nutritional value of cooked rice by adding milk in cooking water. Cooked and soaked rice with five different levels of milk in cooking water (0%, A: 30%, B: 50%, C: 70%, D: 100%, E) was tested for rheological parameters, fine structural changes, sensory evaluation. 1. Water absorbance of raw rice in cooking water with varying amountes of milk, was tested at $5^{\circ}C$ and $15^{\circ}C$ for 2 hours. Water absorption ratio was decreased as milk content was increased and soaking temperature was low. Time for maximum water absorption of sample A was 40 min at 1$15^{\circ}C$ but for sample B to D, it was not reached until 120 min. 2. Electronmicroscopic observation revealed that starch granules of rice lost their regular forms by soaking for 90 minutes, but recovered most of initial regularity after 24 hours. Increase in milk content of soaking water decreased marginal sharpness of the starch granule, presumably due to reduced swelling of the granule. 3. Degree of gelatinization of cooked rice was highest in sample A and progressively decreased as milk content was increased. It was, however, increased in all samples when the cooking water to rice ratio was raised from 160% to 180%. During 4 hour storage, rates of retrogradation were not different between A and B samples, but those of C, D and E were about 2.5 times higher than A and B under the optimal condition of 170% cooking water to rice ratio. This was in the order reverse to hardness order of AC>A, D＞E at cooking water to rice ratios of 160% and 170%, above which A sample surpassed the rest of samples. 4. Sensory evaluation conducted by fifteen university students as panelists showed that there were more significant differences among five samples in flavour, texture than appearance and a notable preference for b and C over A, D and E.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.626-631
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• 1993

The effects of mugwort on some physicochemical properties of rice flour, on the viscosity of rice flour pastes (2 and 4%), on the hardness and the freeze-thaw stability of rice flour gels (20 and 40%), and on the degree of gelatinization (DG) of pastes and gels were investigated. By addition of mugwort, water holding capacity, swelling power, and solubility of rice flour were increased. The rice flour pastes became thicker by addition of mugwort, but viscosities of both the rice flour pastes and the rice flour-mugwort pastes, without noticeable difference between them, were decreased during storage at $25^{\circ}C\;and\;4^{\circ}C$ for 7 days. The rice flour gels became firmer by addition of mugwort and hardnesses of both the rice flour gels and the rice flour-mugwort gels were increased during storage, especially at $4^{\circ}C$. DGs, measured by glucoamylase digestion, of pastes and gels were decreased slightly during storage. Freeze-thaw stability of gels was not affected by addition of mugwort.

• Korean Journal of Food Science and Technology
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• v.16 no.1
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• pp.11-16
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• 1984

Rheological properties of waxy and non-waxy rice starch solutions were evaluated with a narrow gap rotational and Cannon Fenske viscometers. The gelatinized rice starch solutions containing 0.2-1.0% starch displayed pseudoplastic flow behavior. At higher starch level, degree of pseudoplasticity of waxy rice starch solutions increased, while that of non-waxy rice did not changed apparently. The consistency coefficient (K) of non-waxy rice starch solutions increased with increasing gelatinization temperature, but waxy rice starch solutions remained constant, and in alkaline aqueous solutions both of them showed increasing K values. The value of K increased exponentially with an increase in concentration. The effect of the temperature on the viscosity of the solutions followed Arrhenius' type equation, and the activation energies were in the range of 3.675-3.775 kcal/g-mol that were near to that of pure water. The changes of reduced viscosity with concentration were followed Huggin's equation and the values of intrinsic viscosity and interaction coefficient were 0.78-1.59 dl/g and 0.67-2.75, respectively.

• Korean Journal of Food Science and Technology
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• v.20 no.4
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• pp.463-469
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• 1988

The effects of moisture content and particle size of rice flour on the physical properties of the extrudate were examined by using a autogeneous single screw extruder. The moisture contents tested were in the range of 17-28% and the particle sizes were 18-60mesh and 60-120mesh. Samples were taken at different temperatures from the start-up period to the steady state operation. The expansion ratio increased and bulk density decreased as the moisture content and particle size of the flour decreased. The cutting force decreased and the air cell size became uniform as the moisture content and particle size of the flour decreased. As the moisture content increased, the yellowness of the extrudate powder decreased, while the lightness increased, the apparent viscosity increased and the water soluble index decreased. Gelatinization and partial dextrinization were apparent during the extrusion process, and the degree of dextrinization was appeared to be influenced by the levels of moisture content and particle size of rice flour.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.2
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• pp.175-180
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• 2003

Effect of the addition of maltitol to Korean rice cake (Karedduk) on its retrogradation was examined. Degree of retrogradation was also examined in terms of recrystallinity of starch and color change with a differential scanning calorimeter. As a result, retrogradation was suppressed by the increasing addition of maltitol. In particular, enthalpy showed a tendency to decrease at $25^{\circ}C$ rather than at 4$^{\circ}C$ during 4 days. In the gelatinization properties using DSC, onset temperature (To) was shown to increase slightly according to storage time. Maximum peak temperature (Tp) was shown to decrease by the addition of maltitol during 4 days. Melting enthalpy was decreased at $25^{\circ}C$ and 4$^{\circ}C$ by the addition of maltitol. The analysis X-ray diffraction also revealed that retrogradation of the Korean rice cake was suppressed by the addition of maltitol because crystalline region did not appear. The addition of maltitol into the Korean rice cake was found to result in an increase of its qualify or color stability.

• Korean Journal of Food Science and Technology
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• v.5 no.2
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• pp.95-100
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• 1973

In order to study the effect of gamma-ray on the storage stability and quality of polished wheat, the grain was irradiated at $50{\sim}1000$ krad levels and quality assessment was made for three-month storage period. The results are summarized as follows: 1) Growth of molds was apparent at equilibrium moisture content above 14.8% of the grain, but their growth was retarded at 250 krad level. 2) Irradiation at 250 krad level had no adverse effect on fat acidity, reducing sugar content and color of the grain. 3) Irradiation of the grain caused the increase of degree of gelatinization and the decrease of viscosity. 4) Irradiation at 250 krad level brought about higher digestibility of the grain but had no effect on the rate of retrogradation.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.934-938
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• 1995

Water soluble fractions (WSF) of wheat bran treated with thermal processes such as autoclaving, microwaving and extrusion were characterized to investigate the structural response of plant cell wall to thermal and mechanical energy. From the chemical analysis and gel filtration chromatography of WSF, gelatinization of starch was found to be the primary solubilizing mechanism of wheat bran, followed by the structural disintegration of fibrous non-starch cell wall materials. It was also found that extrusion process resulted in degrading relatively higher molecular weight non-starch polysaccharides from the cell wall. GC analysis of water soluble non-starch polysaccharides indicates that the arabinoxylan residues of cell wall are the most susceptible site to thermal treatments studied. In particular, the degrading degree of cell wall of wheat bran is the most significant for extrusion accompanying both high temperature and high shear.

• Korean Journal of Food Science and Technology
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• v.18 no.6
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• pp.421-426
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• 1986

The carbohydrate characteristics and storability of two Korean traditional confections Seban-kangjeong (a Korean fried waxy-rice cookie) and starch-dashik (a Korean pressed starch cookie) were studied as compared with two Western confections fried cookie and biscuit. Seban-kangjeong showed lower contents of starch and sucrose and higher content of reducing sugar whereas starch-dashik showed higher contents of starch and sucrose and lower content of reducing sugar. Moisture content was higher in Korean confections than in Western confections. The degree of gelatinization was higher in Seban-kangjeong and fried cookie which were made through a frying process. Moisture adsorption isotherms were constructed for the four products. In storage test for 6 months under different temperature and humidity conditions, the relative humidity maintaining the initial moisture content of products was 68% for Seban-kangjeong and starch-dashik and 20% for fried cookie and biscuit. The ratio of retrogradation in storage was 15% in Seban-kangjeong, 20% in starchdashik and 28% in fried cookie and biscuit, showing the lowest progress in freezer storage.