• Journal of the East Asian Society of Dietary Life
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• v.16 no.4
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• pp.429-437
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• 2006

The quality of Jeung-pyun made with frozen rice batter was evaluated according to variations in the freezing temperature of the batter. The physicochemical sensory and rheological characteristics of Jeung-pyun were analyzed. The rice batter was stored at -20$^{\circ}C$, -40$^{\circ}C$, and -70$^{\circ}C$ for up to 4 weeks. Statistical data analysis was completed using the SAS program. The pH, and brix percentage of Jeung-pyun batter decreased during the fermentation. In carbon dioxide evolution during fermentation, the levels of the sample stored at -40$^{\circ}C$:, and -70$^{\circ}C$ for 3$\sim$4 weeks were significantly higher than that of the sample stored at -20$^{\circ}C$. The Jeung-pyun moisture content was not significantly affected by freezing temperature or storage times. Specific volume of Jeung-pyun made with rice batter stored at -40$^{\circ}C$, and -70$^{\circ}C$ for 4 weeks was significantly higher than that stored at -20$^{\circ}C$. In sensory evaluation of the stored sample for 4 weeks, the overall quality of Jeung-pyun was not significantly different between with the control and the -20$^{\circ}C$ sample, and between the control and the -40$^{\circ}C$ sample. Among the rheological properties measured with a rheometer on Jeung-pyun made with batter stored sample for 4 weeks at -20$^{\circ}C$, -40$^{\circ}C$ and unfrozen batter, the hardness was increased over the storage time, but the difference was not significant. In conclusion, the most suitable freezing temperature of the rice batter for the manufacture of Jeung-pyun was proposed to be -40$^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.355-359
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• 1993

The effects of alum un the physicochemical properties of non-waxy and waxy rice starches were investigated. The swelling powers of non-waxy and waxy rice starches with $0.05{\sim}1.0%(w/w)$ alum were increased remarkably in comparison with rice starches without alum, but those of rice starches with alum above 1.0%(w/w) concentration were decreased slowly with the increasing amount of alum. While solubility of the non-waxy starch with $0.05{\sim}1.0%(w/w)$ alum was elevated gradually with the increasing temperature. that of the waxy starch was decreased regardless temperature. But solubilities of both rice starches with alum concentration above 1.0%(w/w) exhibited no significant changes. The more alum in the system, the higher and the lower blue value were resulted in non-waxy rice starch and waxy rice starch, respectively. From amylograms, it was found that alum increased breakdown and initial pasting temperatures for both rice starches, but reduced setback.

• Journal of the East Asian Society of Dietary Life
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• v.27 no.3
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• pp.348-363
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• 2017

We analyzed the mixed culture characteristics of isolated brewing fungi obtained from Korean traditional nuruk for their development as fermentation starters. In a previous study, we selected appropriate fungi strains based on their large fungi bodies and strong enzyme activities. These fungi strains were mixed cultured under various combination of ratios, pHs and temperatures. As a result, total acidities of R. delemar mixed culture media were higher than those of A. oryzae cultured at $20^{\circ}C$ and $37^{\circ}C$. The pHs of A. luchuensis 34-1 and A. oryzae 37-7 as well as R. delemar 58-8 and A. oryzae 37-7 mixed culture media gradually increased with the culture period. On the contrary, total acidities of the mixed culture media gradually decreased. ${\alpha}-Amylase$ activities of R. delemar 26-4 and R. oryzae 82-7 mixed culture media were strong at $20^{\circ}C$ and pH 4, glucoamylase activities of R. delemar 58-8 and A. oryzae 37-7 were strong at $37^{\circ}C$, pH 3 and 1:2 ratio, and acidic protease activities of R. delemar 26-4 and A. oryzae 78-5 were strong at $20^{\circ}C$, pH 4 and 1:4 ratio. This study provides the optimal mixed culture conditions for fermentation starters based on changes in pH and total acidity, favorable enzyme activities, and fungi varieties.

• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.278-286
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• 2023

The present work evaluated the production of biohydrogen under mesophilic and thermophilic conditions through dark fermentation of palm oil mill effluent (POME) in batch mode using the design of experiment methodology. Response surface methodology (RSM) was applied to investigate the influence of the two significant parameters, POME concentration as substrate (5, 12.5, and 20 g/l), and volumetric substrate to inoculum ratio (1:1, 1:1.5, and 1:2, v/v.%), with inoculum concentration of 14.3 g VSS/l. All the experiments were analyzed at 37 ℃ and 55 ℃ at an incubation time of 24 h. The highest chemical oxygen demand (COD) removal, hydrogen content (H₂%), and hydrogen yield (HY) at a substrate concentration of 12.5 g COD/l and S:I ratio of 1:1.5 in mesophilic and thermophilic conditions were obtained (27.3, 24.2%), (57.92, 66.24%), and (6.43, 12.27 ml H₂/g COD_rem), respectively. The results show that thermophilic temperature in terms of COD removal was more effective for higher COD concentrations than for lower concentrations. Optimum parameters projected by RSM with S:I ratio of 1:1.6 and POME concentration of 14.3 g COD/l showed higher results in both temperatures. It is recognized how RSM and optimization processes can predict and affect the process performance under different operational conditions.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.11
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• pp.1652-1662
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• 2014

The present study investigated the optimum blending condition of protected fat, choline and yeast culture for lowering of rumen temperature. The Box Benken experimental design, a fractional factorial arrangement, and response surface methodology were employed. The optimum blending condition was determined using the rumen simulated in vitro fermentation. An additive formulated on the optimum condition contained 50% of protected fat, 25% of yeast culture, 5% of choline, 7% of organic zinc, 6.5% of cinnamon, and 6.5% of stevioside. The feed additive was supplemented at a rate of 0.1% of diet (orchard grass:concentrate, 3:7) and compared with a control which had no additive. The treatment resulted in lower volatile fatty acid (VFA) concentration and biogas than the control. To investigate the effect of the optimized additive and feed energy levels on rumen and rectal temperatures, four rumen cannulated Hanwoo (Korean native beef breed) steers were in a $4{\times}4$ Latin square design. Energy levels were varied to low and high by altering the ratio of forage to concentrate in diet: low energy (6:4) and high energy (4:6). The additive was added at a rate of 0.1% of the diet. The following parameters were measured; feed intake, rumen and rectal temperatures, ruminal pH and VFA concentration. This study was conducted in an environmentally controlled house with temperature set at $30^{\circ}C$ and relative humidity levels of 70%. Steers were housed individually in raised crates to facilitate collection of urine and feces. The adaptation period was for 14 days, 2 days for sampling and 7 days for resting the animals. The additive significantly reduced both rumen (p<0.01) and rectal temperatures (p<0.001) without depressed feed intake. There were interactions (p<0.01) between energy level and additive on ruminal temperature. Neither additive nor energy level had an effect on total VFA concentration. The additive however, significantly increased (p<0.01) propionate and subsequently had lower acetate:propionate (A/P) ratios than non-additive supplementation. High concentrate diets had significantly lower pH. Interactions between energy and additive were observed (p<0.01) in ammonia nitrogen production. Supplementation of diets with the additive resulted in lower rumen and rectal temperatures, hence the additive showed promise in alleviating undesirable effects of heat stress in cattle.

• Food Science and Preservation
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• v.17 no.6
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• pp.881-888
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• 2010

We investigated the influence of carbonic maceration (CM) at different temperatures on the enological characteristics of Campbell Early grape must. Total acid levels decreased after 5 d, as CM temperature increased. All of pH; redness; and total anthocyanin, polyphenol, and tannin concentrations increased as CM temperature increased. Malic acid concentration fell at high CM temperatures, but lactic acid level increased under such conditions. Polyphenol levels and antioxidant activity were higher when CM was conducted at $35^{\circ}C$ than at other temperatures. The results show that the temperature of CM treatment greatly influences wine quality factors such as color, taste, and antioxidant capacity.

• Microbiology and Biotechnology Letters
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• v.41 no.2
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• pp.168-175
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• 2013

In this study we investigated the possibility of preparing brewed brown rice makgeolli, a traditional Korean rice wine, under diverse conditions. For this purpose the physicochemical characteristics of makgeolli brewed at different temperatures, utilizing a variety of nuruks, the traditional Korean fermentation agent, were studied. The alcohol content was seen to be highest when brewing occurred at $30^{\circ}C$, with the nuruk TN producing 16.2%. At $20^{\circ}C$TN produced 14.1% alcohol content. The alcohol content was therefore higher, by about 2%, for $30^{\circ}C$ fermentations than $20^{\circ}C$ fermentations. Similarly, saccharifying activity was influenced by temperature and sugar content, with a higher activity seen at $30^{\circ}C$ than at $20^{\circ}C$. As the fermentations progressed acidification petered out, with titratable acidity being 0.50-0.67% in all end samples. On the Hunter L, a, b scale; the a value decreased slightly, while the b value increased steadily during the fermentation process. Measurements of total organic acids were highest at $30^{\circ}C$, with the nuruk AK, at about 550 mg%. The content of citric acid was the highest at $30^{\circ}C$, being 230-310 mg% in all samples. However, more lactic acid was detected at $20^{\circ}C$ than at $30^{\circ}C$. Total free amino acid was highest at $30^{\circ}C$, with TN at $8,605{\mu}g/ml$, AK at $6,083{\mu}g/ml$, and RJ at $2,381{\mu}g/ml$. Total free amino acid and essential amino acid was shown to be higher at $30^{\circ}C$ than at $20^{\circ}C$. The bioactive substance ${\gamma}$-aminobutyric acid was also higher at $30^{\circ}C$, with TN at $223{\mu}g/ml$. From all of these results, we surmise that brown rice makgeolli manufacturing conditions are optimal at $30^{\circ}C$ fermentation temperatures and using the nuruk TN for brewing vinegar. In addition, the nuruk used clearly affects the quality of brown rice makgeolli and an appropriate method to determine the best nuruk for various purposes should be pursued.

• Journal of the Korean Society of Food Culture
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• v.35 no.4
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• pp.342-350
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• 2020

This study examined the methods used in household doenjang (Korean soybean paste) production. Nine hundred forty-three responses were obtained using a nationwide, questionnaire-based survey (2018-2019) with non-probabilistic snowballing sampling. Consistent with previous studies, the respondents were primarily over the age of 50 years (97.1%) and female (97.9%). In addition to soybeans, the most used ingredients were red pepper (85.8%) and charcoal (85.5%), which most respondents obtained through direct farming (50.4-59.9%). Seasonal production occurred later in the higher latitude regions (Gyeonggi-do, Gangwon-do, Chungcheong-do) (p < 0.01), which have lower average temperatures, and the fermentation period was shorter in the lower latitude regions (Jeolla-do, Gyeongsang-do, Jeju-do) (p < 0.01), which have higher average temperatures. There were no significant regional differences in the season when doenjang was made, with most production occurring during January and February (81.1%). Most respondents (71.3%) made doenjang using homemade meju (soybean block used as a starter) in a traditional way to allow the microorganisms to be naturally inoculated. These results could be used as a basis for future research on topics such as starter development, standardized production, and safety of household doenjang.

• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.21-25
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• 1997

Application of the color indicators to kimchi packages was investigated in order to monitor the ripeness of commercial kimchi products during storage and distribution. Kimchi was packed in polypropylene (PP) tray and nylon/cast polypropylene (Ny/CPP) lid where the indicating sachet consisting of $CO_2$ absorbent and chemical dye (bromocresol purple and methyl red) was attached. The ripeness of kimchi during storage at $0{\sim}20^{\circ}C$ was measured in terms of pH and titratable acidity (TA), which were compared with Hunter color values of the indicators. The color of bromocresol purple dye turned from light blue to purple, while that of methyl red turned from light yellow to red. Regardless of the storage temperatures, Hunter b values of bromocresol purple type and Hunter a values of methyl red type appeared to be proportional to both the pH and TA values of kimchi. These results suggest that the color indicators be employed as one of the effective techniques for sensing the ripeness of packaged kimchi products without destructing the package.

• Journal of the Korean Society of Food Culture
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• v.24 no.3
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• pp.295-307
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• 2009

The principal objective of this study was to develop and standardize a preparation method for low-sodium tomato jangachi (traditional Korean pickle) via short-term fermentation with immature green cherry tomatoes. In order to determine the preferred concentrations of soy sauce and soaking temperatures of immature cherry tomato pickles in different stages of storage, we conducted an analysis of physico-chemical characteristics and microbiological properties, and also performed a preference test on samples of immature green cherry tomato pickles. Immature cherry tomatoes were prepared in three different soy sauce concentrations --20, 40, and 60%-- and three different soaking temperatures --60, 80, and 100$^{\circ}C$-- and then stored for 28 days at 5$^{\circ}C$. As a result, the pH increased significantly with increases in the amount of soy in the dipping solution (p<0.05). The saltiness was maintained at levels of approximately $0.17{\sim}0.28%$ (20% group), $0.32{\sim}0.67%$% (40%group), $0.48{\sim}1.00%$ (60% group) during storage periods. These results show that the saltiness of immature cherry tomato pickles was substantially lower than that of commercial pickles. The contents of reducing sugar and lightness decreased significantly with increasing concentrations of soy dipping solution. The redness and yellowness values of the tomatoes decreased significantly with increasing concentrations of soy sauce. Additionally, the lower the concentration of soy sauce used, the more rapidly the hardness of the immature cherry tomato pickles was reduced at 100$^{\circ}C$. PME activity moved within a narrow range, and then stabilized during the storage period. With regard to the results of the consumer preference test, 20%-100$^{\circ}C$ was the most preferred condition overall, 40%-80$^{\circ}C$ was the condition in which the texture was most preferred, and 40%-80$^{\circ}C$ was the condition that yielded the highest color scores.