• Journal of Food Hygiene and Safety
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• v.31 no.4
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• pp.278-285
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• 2016

This study used response surface methodology (RSM) in an effort to optimize the ultrasoundassisted extraction condition of Camellia sinensis L. and Artemisia argyi mixture in order to increase extraction yield in the extract. The effects of three independent variables, $X_1$ (Mixture ratio, 60-80%), $X_2$ (Ratio of water to raw material, 20~100 mL/g), and $X_3$ (Extraction time, 25-145 min), were investigated at three levels using Box-Behnken design (BBD) to obtain the highest extraction efficiency. Y (Extraction yield) was chosen as dependent variable. Our result showed that the coefficient of determination ($R^2$) of the model was 0.9747, with significant at the level of p < 0.002. Furthermore, the predicted values of each variable were similar to the actual values. The optimum extraction conditions were as follows: mixture ratio of 85.86%, ratio of water to raw material of 92.73 mL/g, and extraction time of 56.52 min. At these conditions, predicted extraction yield was 30.03%. The analysis of variance (ANOVA) indicated a high goodness of model fit and the success of the RSM method for optimizing extraction conditions of Camellia sinensis L. and Artemisia argyi mixture.

• Food Science of Animal Resources
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• v.28 no.5
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• pp.587-595
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• 2008

In order to develop a new starter for fermented milk, 1037 bacterial strains were isolated from raw milk. The strain that showed excellent acid producing and angiotensin converting enzyme (ACE) inhibitory activity (88.6%) was selected and identified as a Lactobacillus zeae based on the result of API carbohydrate fermentation pattern and 16S rDNA sequence. Lactobacillus zeae RMK354 was investigated further to study its physiological characteristics. It showed strong ACE inhibitory activity compared with commercial LAB starters tested. The optimum growth temperature of L. zeae RMK354 was $40^{\circ}C$ and it took 10 hr to reach pH 4.3 under this condition. L. zeae RMK354 showed more sensitive to penicillin-G, bacitracin, novobiocin, in a comparison of 14 different antibiotics, and showed most resistance to polymyxin B and vancomycin. It showed higher esterase and leucine arylamidase activities compared with 16 other enzymes. It was comparatively tolerant to bile juice and able to survive at pH 2 for 3 hr. It showed inhibitory activity against Salmonella Typhimurium with the rate of 60%. Based on these and previous results, L. zeae RMK354 could be an excellent starter culture for fermented milk with high level of ACE inhibitory activity.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.285-292
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• 1999

An analytical method applicable to quality control and its optimum conditions were studied for rapid and efficient analysis of sorbic and benzoic acids used as preservatives in the commercial soybean paste. In gas chromatographic analysis of sorbic and benzoic acids, the application of HP-FFAP (acid modified polyethylene) wide bore column improved the separation ability significantly. By setting the oven temperature of GC to $200^{\circ}C$, the total elapsed time for quantitative analysis was also reduced to the level required in using packed column. By extracting sorbic and benzoic acids from soybean paste with an automatic steam distillation device, the elapsed time for analysis was reduced by 80% more compared to using conventional steam distillation method. The recoveries of sorbic and benzoic acids by the automatic steam distillation were 98.1% and 99.9%, respectively. The sorbic acid was found in 3 samples of 14 commercial soybean pastes, of which contents were $466{\sim}530ppm$, while $0.3{\sim}4.4ppm$ of benzoic acid was found in all the samples.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.329-335
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• 1999

The yield of oleoresin content and functionality of fresh garlic were compared according to varying extraction conditions by microwave-assisted extraction (MAE) and conventional extraction (CE) methods. When different extracting conditions were applied, there was no significant difference of extraction methods in the oleoresin content. However, in the case of the CE, the optimum extraction time was two hours, while the other was about five minutes which meant that the extraction time was shortened drastically. The electron donating abilities showed a similar level which was 64% by both methods, using water. And, in the case of ethanol extraction, it resulted 63% and 51% by CE and MAE, respectively. The nitrite scavenging effect diminished while pH was increasing and especially, in the case of pH 1.2, it showed a high elimination effect of more than 90%. There was no difference of extraction methods. The tyrosinase inhibitory effect was 47% and 60% by CE and MAE, respectively in the case of the water extract. The ethanol extract showed similar or a slight lower inhibition of 45% and 39%. The angiotensin I-converting enzyme inhibitory effect showed more powerful activity in the case of MAE extract than CE extract, but there was not an increase relating to reaction time of enzyme. Also, pyruvic acid content was $44.8\;and\;36.0{\mu}moles$ per one gram of a garlic by CE and MAE, respectively when water was used, and was $28.6\;and\;32.0{\mu}moles$ by CE and MAE when ethanol was used. Again, there was no big difference between CE and MAE methods.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.7-14
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• 2003

Physico-chemical and sensory characteristics of six dongchimi cultivars were evaluated. Moisture and sugar contents were 94.2% and $4.30^{\circ}Brix$ for three spring radish cultivars, while 92.9% and $7.30^{\circ}Brix$ for three autumn ones. pH $(5.7{\sim}6.1)$ and acidity $(0.09{\sim}0.12%)$ did not show significant differences among cultivars. pH decreased steadily up to 21 days to reach optimum pH of 4.0. The maximum number of total lactic acid bacteria, $10^8{\sim}10^9\;CFU/mL$, was reached at pH 4.0. The final acidity of spring radishes was lower than that of autumn ones, and was proportional to the sugar content of the radishes. The firmness of spring radish decreased rapidly compared to the autumn ones. Cheongbok was found suitable for dongchimi, because its firmness level was maintained around $165.0{\times}10^3\;N/m^2$ at 35 days. Sensory evaluation revealed 96371 among spring radishes and cheongbok among autumn radishes scored high in firmness, chewiness, flavor, and overall acceptance. These results suggest that autumn radishes are suitable for dongchimi fermentation with cheongbok being the best among the cultivars.

• Korean Journal of Food Science and Technology
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• v.15 no.3
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• pp.231-237
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• 1983

In order to develop the commercial storage method of chestnut by irradiation combined with natural low temperature, a chestnut variety Ok-gwang was stored in a natural low temperature storage room ($450{\times}650{\times}250$ cmH; year-round temperature change, $2-17^{\circ}C$; R.H., 80-85%) on batch scale followed by irradiation with optimum dose level. Sprouting rate of chestnut was 100% after seven month storage in control whereas that of 20-25 Krad irradiated group was only 5-15%. In comparison of rotting rate, weight loss and texture, 25 Krad irradiated group was better than that of control. Moisture and reducing sugar were increased in contrast with the decrease of total sugar during nine month storage and these changes were more remarkable in control. Ascorbic acid content was slightly decreased both in control and irradiated group; more decrement was noticed in control.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.4
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• pp.229-236
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• 1991

A study on the estimation of the stock density and biomass of Perinereis aibuhitensis in the tidal zone in Sosan, Chungchongnam-do, Korea was carried out from June to July 1988. A preliminary survey was conducted to determine the distribution pattern of the species and the optimum sample size for setting up the sampling design. The stock densities of the species by stratum and by subarea were estimated using the stratified random sampling method, based upon the results of preliminary survey. The differences in density between strata as well as among subareas were tested to decide whether they can be combined together for estimating the overall stock biomass or not. The results of the survey showed that p. aibuhitensis were randomly distributed(Poisson distribution) and the number of quadrats which satisfies a reasonable level of precision was determined to be five by stratum. The densities between strata were not significantly different, while densities among subareas were different. Subarea C showed the highest density with the mean of $53.9g/m^2$ and followed by subarea B. The density of subarea A was the lowest with the mean of $18.2g/m^2$. The overall mean density from the study area was $32.4g/m^2$ with the coefficient of variance(CV) of $6.8\%$ The overall stock biomass was estimated to be 147.5mt in this area.

• KSBB Journal
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• v.24 no.3
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• pp.303-311
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• 2009

A scaling up study for the exopolysaccharide (EPS) production by submerged culture of Ganoderma lucidum was carried out in jar fermenter systems (2.6, 20 and 75 L) under bi-staged pH process. Profiles of dissolved oxygen (DO) and volumetric coefficient of oxygen transfer ($k_La$) as a function of operating variables (agitation speed and aeration rate) was investigated, and a correlation between $k_La$ and operating variables was analysed statistically. Under bi-staged pH process, no limitation of DO was observed at agitation speeds tested in the range of 200 and 600 rpm, and the highest EPS production was obtained at the level of DO of $40{\sim}80%$. From the regression analysis, the relation between $k_La$, gas velocity (Vs), stirrer speed (N) and impeller diameter (Di) could be expressed as : $$k_La=0.555{\times}Vs^{0.42}{\times}(N^3{\times}Di^2)^{0.33}\;(R^2=0.925,\;p<0.05)$$ It was found that under 2.6 L jar fermenter, the optimum agitation speed and aeration rate was 400 rpm and 1 vvm, respectively, obtaining the EPS production of 15.43 g/L. Under the submerged cultivation of G. lucidum in jar fermenters of $2.6{\sim}75\;L$, the similar EPS yields at each fermenter were achieved during scaling up based on $k_La$, and $k_La$ value for maximum EPS production was $85.4{\pm}26.70\;h^{-1}$.

• Journal of Aquaculture
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• v.19 no.3
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• pp.166-172
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• 2006

Induced androgenesis, a form of artificial parthenogenesis is an important tool for the generation and use of genetically isogenic or clonal fish strain. An optimized protocol for the genetic inactivation of mud loach (Misgurnus mizolepis) oocytes (i.e. production of androgenetic haploid) was developed using UV-irradiation. Various dose levels of UV significantly affected the fertilizing capacity of the eggs, hatchability of embryos and incidence of haploidy. Based on the extensive examinations of treatment conditions on embryo viability and haploid incidence, the optimum dose level of UV irradiation was turned out to be $10,800ergs/mm^2$ with 56.9% of hatching success and 94.6% of haploidy. The overall yield of putative androgen under optimized treatment condition was more than 50% out of total eggs inseminated. The success of androgenetic reproduction of haploid genome was verified by flow cytometry and PCR amplification of transgene that is exclusive to either one of parental sexes. However, a small portion $(8\sim11%)$ of presumed androgenetic haploid larvae was proven to contain residual DNA fragment(s) from maternal parent.

• Applied Biological Chemistry
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• v.20 no.1
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• pp.33-42
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• 1977

Asparagine biosynthesis by soybean sprouts grown under the dark conditions has been demonstrated. The amount of free asparagine synthesized in ten day-old soybean sprouts increases to 22.7% on the dry weight base. The effects of nitrogen compounds such as $NH_4Cl,\;(NH_4)_2SO_4$ and urea on asparagine synthesis during the sprouting were examined and the results showed that urea was more effective than other two compounds. Glutamine-dependent asparagine synthetase was partially purified (8.6 folds) through ammonium sulfate fractionation, followed by Sephadex G-150 gel filtration. The enzyme was very labile and required protection by thiol groups or high level of glycerol. The mixture of ATP and $Mg^{++}$ ion also stabilized the enzyme activity. The enzyme utilized glutamine more effectively than ${NH_4}^+$ as an amide donor for the formation of asparagine. The enzyme required L-aspartate (Km=3.1 mM), L-glutamine, ATP and $Mg^{++}$. It showed pH optimum of 7.5 and catalyzed the formation of ${\beta}-aspartyl$ hydroxamate in the presence of L-aspartate, ATP, $Mg^{++}$ and $NH_2OH$ in the reaction mixture.