• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.730-736
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• 1997

Pasteurization of low salt dongchimi juice was studied for the effect of heating temperature and time on total viable counts and some physicochemical and sensory properties. The juice was prepared by fermentation of the radish at $20^{\circ}C$ in 0.5% NaCl solution. Heating the juice (pH 3.8) at $60{\sim}100^{\circ}C\;for\;5{\sim}30$ min caused little changes in pH and total acidity while the lightness (L value) was decreased and the turbidity, a and b values of color were increased as the heating temperature and time increased. The total viable counts of microorganisms was significantly decreased to 18 at $60^{\circ}C$ and 6 at $70^{\circ}C$ after 30 min heating and was not detected after heating at 90 and $100^{\circ}C$ for 10 min. The sensory test showed that heating up to $70^{\circ}C$ for 20 min caused a little cooked off-flavor. After storage of the pasteurized juices at $30^{\circ}C$ for 10 days, the pH, total acidity and color were changed little while the unheated juice changed significantly. The total viable counts of microorganisms was also remained initial level after pasteurization. Therefore pasteurization at $60^{\circ}C$ for 30 min or $70^{\circ}C$ for 20 min was recommendable in the aspects of storage stability and quality characteristics.

• Korean Journal of Food Science and Technology
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• v.27 no.3
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• pp.336-341
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• 1995

Effect on alginate, pectin and Ca salts on textural properties of whole soybean gel(soygel) was investigated. The soygel was prepared by addition of sodium alginate, pectin and Ca salts into whole soy flour(300 mesh, WSF) suspension followed by through mixing. Addition of sodium alginate or pectin into WSF suspension significantly increased the hardness, adhesiveness and cohesiveness of the gel. The most uniform gel was obtained by $12{\sim}15%$ addition of sodium alginate or pectin, while their mixture rather decreased the textural properties. Sensory evaluation by ranking test for the gels showed that 12% sodium alginate and 0.125g $CaSO_4/g$ WSF produced the most desirable gel in terms of elasticity, uniformity, smoothness and total acceptability, followed by 12% sodium alginate and 0.12g Ca $gluconate-CaSO_4$(50 : 50). From the results, the optimal preparative conditions for soygel were suspension of WSF in 10 times of water(v/w), addition of 12% sodium alginate(w/w of WSF) and 12.5% $CaSO_4$ or Ca $gluconate-CaSO_4$(50 : 50) into WSF suspension followed by gel formation at $4^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.27 no.3
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• pp.329-335
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• 1995

Rheological properties of whole soybean gel(soygel) were investigated as affected by the water addition ratio, stirring time and Ca salts. The soygel was prepared by suspension of whole soy flour(WSF, 300 mesh) in boiling water, addition of sodium alginate and Ca salts followed by thorough mixing and gel formation at $4^{\circ}C$. The texture properties of hardness, adhesiveness and cohesiveness of the gel were increased as the stirring time prolonged from 5 to 30 minutes. From the results of the rheological and sensory properties, 20 minutes of stirring time was selected for whole soybean gel preparation. Eventhough increase in water addition ratio from 8 to 12 times(water/WSF, v/w) resulted a decrease in hardness and adhesiveness, 10 times ratio was chosen as proper the water addition based on textural uniformity. Among the Ca salts, $CaSO_4$ produced the highest hardness followed by Ca $gluconate-CaSO_4$ mixture(413g) and Ca gluconate at the water addition level of 10 times. In order to determine the amounts of Ca salts, and 0.125g of Ca gluconate or $CaSO_4$ per g WSF were found to be optimum in terms of textural and sensory properties. The proper mixing ratio of Ca gluconate and $CaSO_4$ was found to be 50 : 50, 25 : 75 and 0 : 100.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.889-892
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• 2005

Standardized method based on extraction, filtration, and gas chromatography (GC) was developed far propylene glycol analysis to set hygienic norm of safety measure for foods under governmental control. Various columns were tested fur propylene glycol analysis by GC with flame ionization detector. Known amount of propylene glycol was spiked into wheat flour dough and analyzed by developed method. Results showed 101.60% recovery rate for propylene glycol with HP-5 column. Reproducibility test of standards recorded 0.30 for standard variation and 0,42% for relative variation. Using analytical method established, contents of propylene glycol in more than hundred different foods were monitored. Propylene glycol was detected in most foods, indicating propylene glycol is not only commonly added during food preparation, but also is contained naturally in food.

• Korean Journal of Food Science and Technology
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• v.24 no.5
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• pp.504-510
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• 1992

Several single or mixed water-miscible organic solvent systems were investigated to develop the most effective solvent system for enzymatic synthesis of N-benzoylaspartame(BzAPM). The BzAPM was prepared by immobilized thermolysin with using N-benzoyl-L-aspartic acid(Bz-Asp) and L-phenylalanine methyl ester(PheOMe). The solubilities of BzAPM and L-phenylalanine were highest in 4.5% methanol(1.89 and 1.79%, respectively) among the solvents system investigated while a mixed solvent system of 25% dimethyl sulfoxide(DMSO) and 20% polyethylene glycol(PEG) 200 showed relatively high values. The synthetic activity of BzAPM as well as initial reaction rate were found to be high in 45% methanol, 45% DMSO and a mixed solvent of 25% DMSO and 20% PEM 200. The imobilized thermolysin was most stable in 25% DMSO and 20% PEG 200 during storage at $40^{\circ}C$ for 42 days. PheOMe in the same solvent system was also found fairly stable against non-enzymatic decomposition at $40^{\circ}C$. Based on the synthetic efficiency and stability, the solvent system containing 25% DMSO and 20% PEG 200 was selected to be appropriate for the enzymatic synthesis of BzAPM.

• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.720-727
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• 2001

This study was carried to investigate the changes in physical and chemical properties of Yukwa during preparation with addition of antioxidants and to develop its storage condition. Antioxidants (tocopherol and Oxyfos) were used in syrup coating and the packaging materials used were PET/EVOH $(16\;{\mu}m)/PL$ : P1 and PET/EVOH $(24\;{\mu}m)/PL$ : P2 (YOP1: P1 with Oxyfos, YOP2 : P2 with Oxyfos, YTP1 : P1 with tocopherol, YTP2 : P2 with tocopherol). Color values measured for Yukwa showed that L values of YOP1, YOP2, YTP1 and YTP2 were changed little during storage while a and b values of YOP1, YOP2, YTP1 and YTP2 were slightly decreased. Hardness and chewiness in textural properties were also decreased during storage. Yukwa packed in YOPl and YOP2 maintained less than 40 in peroxide value during for 12 weeks of storage period. The major fatty acid composition of frying oil were linoleic acid (54.2%), oleic acid (23.4%), palmitic acid (11.3%), linolenic acid (6.5%) and stearic acid (4.6%). There was no difference in composition of fatty acid during storage. Sensory evaluation (Yukwa odor and rancid odor) showed very similar results with determined by electronic nose. YTP1 and YTP2 had maintained sensory characteristics of Yukwa during 10 weeks storage.

• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.728-736
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• 2001

Effects of packaging material and oxygen absorbant on physical and chemical properties of Yukwu were studied during storage to develop packaging conditions. The packaging materials used were PET/EVOH $(16\;{\mu}m)/PL$ : P1 and PET/EVOH $(24\;{\mu}m)/PL$ : P2 with or without oxygen absorbent (E1A : P1 and E2A : P2 for w/ $O_2$, absorbent, E1EA : P1 and E2EA : P2 for w/o $O_2$, absorbent). Color values for Yukwu indicated that L values of E1A, E1EA, E2A and E2EA were decreased during storage while those b values were increased. Hardness and chewiness of Yukwa were generally decreased, however those of E1A and E1EA were rather increased after 6 weeks of storage. Acid value of E2A had maintained less than 2.0 during 12 weeks of storage. E1A, E2A had the below of 20 in peroxide during 12 weeks. Aroma data by using electronic nose showed that there was no difference after 6 week storage time in different packaging materials. Sensory evaluation (Yukwa odor and rancid odor) showed very similar results with electronic nose one. E2A had the highest value of overall acceptability for sensory evaluation. Hardness and cheweness in physical measurement results had the highest correlation with hardness, crispness, overall-acceptability in sensory evaluation results.

• Applied Biological Chemistry
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• v.28 no.2
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• pp.51-55
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• 1985

Dried black soybeans were soaked in water at the temperature range of $4^{\circ}C{\sim}100^{\circ}C$ and in salt or sugar solution at $100^{\circ}C$ in order to investigate their effects on the cooking ratio and diffusion property of color pigments. As the temperature increased, the equilibrated absorbance at 490nm of soaking water after 120min was linearly increased. The activation energy for diffusion of color pigments were found to be 4.23 Kcal/mole at the range of $60^{\circ}C{\sim}100^{\circ}C$ and 8.31 kca1/mo1e at $4^{\circ}C{\sim}60^{\circ}C$. The cooking ratio, % cooked beans after heating, of black soybeans were more affected by the salt concentration that of sugar. Both concentrations reduced the cooking ratio as they increased. The sorption isotherm of Kongjaban showed a quite different curves between the storage at $4^{\circ}C$ and $25^{\circ}C$. The sorption and desorption rates during storage could be represented by the equation of $log({\frac{dw}{dt}}{\times}10^3))=alogt+logb$ with a very high correlation.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.225-230
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• 1991

In this study, several combined effect of KCl addition into bring solution, microwave heating of Chinese radish for 3 minutes and addition of two salt mixtures into half fermented Kakdugi were investigated to compare their improving effects of storage stability of Kakdugi, Kakdugi was prepared by salting in 15% NaCl solution for 2 hours and fermented at $25^{\circ}C$ and determined for the changed in pH, total acidity and reducing sugars. It was found from the result that the combined method of salts addition and heating treatment improved the storage stability by 6.4 folds based on pH change where salts mixture of phosphated, Ca EDTA, and Sod. citrate contributed the most effect. Changed in reducing sugar were greatly reduced by salt mixture addition while microwave heating and KCl addition affected little. Storage of Kakdugi at $4^{\circ}C$ after preparation with combined method could extend the storage life more than 8 folds of those Kakdugi stored at $25^{\circ}C$. However total acidity showed higher values for those prepared by combined method and stored at $4^{\circ}C\;or\;25^{\circ}C$.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.213-218
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• 1991

Addition of salts or their mixtures and microwave heating were studies for their effects on Kakdugi fermentation. The Kakdugi, a Korean fermented Chinese radish, were prepared by salting in 15% NaCl solution and fermented at $25^{\circ}C$. From the results, a first order reaction relationship was found between salt permeated into the radish and time during brining in $5{\sim}10%$ NaCl solution. Addition of 0.05M KCl into 15% NaCl brining solution or microwave heating of salted radish for 3 minutes showed a little decreasing effect on Kakdugi fermentation rate while beating for 1 or 2 minuted resulted a rather increase. When three different salt mixtures in the concentration range of $0.001{\sim}0.01\;M$ were added into half fermented Kakdugi(appr. pH 4.4), the fermentation was greatly controlled based on pH change. Among the salt mixtures, mixture III$(Na_2HPO_4,\;Na_2PO_4,\;NaNO_2,\;Ca\;EDTA,\;Sod.\;citrate)$ showed a most significant effect where the time required to reach pH 4.0 after addition was extended by more than 6 folds when it was compared to the control method.