• KSBB Journal
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• 제16권2호
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• pp.207-211
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• 2001

Statistical experimental design methods were employed to select the cultivation factors influencing latic acid production during the fermentation of kitchen refuses. Working volume and pH swings were identified as the main factors affecting lactic acid production. Optimum pH swing was pH 7.8 and working volume was 125 mL in a 250 mL flask. Under optimum condition, lactic acid was produced at 21.8 g/L, which was 6.2 times higher than produced during uncontrolled fermentation.

• 대한의생명과학회지
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• 제11권4호
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• pp.539-543
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• 2005

Elevated level of serum cholesterol in humans is a risk factor correlated with the development of coronary heart disease. We have screened lactic acid bacteria from pig and human feces for the development of probiotics which have an anti-cholesterol effect. We have used special media to isolate only lactic acid bacteria and they were subjected to the experiments such as oxgal test, carbohydrate fermentation test. Results from the acid tolerance test and growth test in the presence of oxgal demonstrated that some strains would likely survive in thuman stomach, where acidity is high, and in small intestine, where bile fluid is present. In conclusion, we were able to screen lactic acid bacteria which were tolerant against bile acid and supposed to be prominent to lower the cholesterol level in human serum.

• Journal of Chest Surgery
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• 제12권4호
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• pp.395-402
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• 1979

Intracellular pH was determined by distribution of 5.5-dimethyl-2,4-oxazolidlnedione [DMO]in the skeletal muscle of dogs before and after lactic acidosis induced by intravenous infusion of lactic acid solution. After infusion of lactic acid solution arterial pH decreased from 7.40 to around 7.12 [P<0.001]and metabolic acidosis was induced. However, dose-pH change response was not proportional as in the case of hydrochloric acid infusion. During lactic acidosis, intracellular pH changed very little except when venous blood $pCO_2$ increased significantly. The decrease of intracellular pH in lactic acidosis might be due primarily to the increase of intracellular $pCO_2$. And during lactic acidosis, change of extracellular pH was larger than that of intracellular pH, and this was also the case of change In hydrogen Ion concentration in extracellular and intracellular fluid. The fact was estimated that exogenous lactic acid transported into the cell does not contribute to pH change by the participation in the metabolism. Change in plasma potassium Ion concentration was not eminent as metabolic acid-base disturbances by other origin, and changing pattern of Hi/He ratio was not same as Ki/Ke ratio. In spite of no changes in extracellular potassium ion concentration after exogenous lactic acidosis total amount of potassium ion in extracellular fluid increased from 12.62mEg to 18.26mEg [P< 0.05].

• 환경위생공학
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• 제21권4호
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• pp.11-18
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• 2006

This study was carried out to investigate the distribution of Vibrio parahaemolyticus in the Incheon adjacent sea, and antimicrobial effect on growth of Vibrio parahaemolyticus in lactic acid and hydrogen peroxide and combination of lactic acid and hydrogen peroxide. The detected strains were compared geographical, months and sample types. The distribution of Vibrio parahaemolyticus was high at Ganghwa county with 66.1%(336 samples), on 7-9 months with 72.4%(386 samples) and from tireland with 75.0%(90 samples), respectively. The minimun inhibitory concentration (MIC) of lactic acid in Vibrio parahaemolyticus were 1250 ppm at pH 6.5 and 7.0, 625 ppm at pH 6.0. respectively. The minimun inhibitory concentration (MIC) of hydrogen peroxide in Vibrio parahaemolyticus were 25 ppm at pH 6.5 and 7.0, 12.5 ppm at pH 6.0, respectively. MICs of combined treatment of lactic acid and hydrogen peroxide in Vibrio parahaemolyticus were 625 ppm of lactic acid with 12.5 ppm of hydrogen peroxide. The correlations between MICs of lactic acid and hydrogen peroxide in Vibrio parahaemolyticus were obtained through the coefficient of determination($R^2$). $R^2$ value were 1.0000. The antimicrobial effect of lactic acid and hydrogen peroxide in Vibrio parahaemolyticus could be confirmed from the result of this experiment.

• KSBB Journal
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• 제27권3호
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• pp.151-156
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• 2012

Lactic acid is an important product arising from the anaerobic fermentation by lactic acid bacteria (LAB). It is used in the pharmaceutical, cosmetic, chemical, and food industries as well as for biodegradable polymer and green solvent production. The poly lactic acid (PLA) is an important material for bio-plastic manufacturing process. For PLA production by new LAB, we screened LAB isolates from shellfish. A total of 28 LAB were isolated from various shellfishes. They were all Gram positive, oxidase and catalase negative. Based on API 50CHL kit, 7 strains among the 28 isolates were identified as Lactobacillus plantarum, 6 strains as Lactobacillus delbrueckii, 5 strains as Leuconostoc mesenteroides, 3 strains as Lactobacillus brevis, 2 strains as Lactococcus lactis, 1 strain as Lactobacillus salivarius, 1 strain as Lactobacillus paracasei, 1 strain as Lactobacillus pentosus, 1 strain as Lactobacillus fermentum and 1 strain as Pediococcus pentosaceu. Also, we examined the amount of total lactic acid produced by these new strains by HPLC analysis with Chiralpak MA column. One strain E-3 from Mytilus edulis was indentified as Lactobacillus plantarum and found to produce 20.0 g/L of D-form lactic acid from 20 g/L of dextrose. Further studies are underway to increase the D-lactic acid production by E-3.

• 한국축산식품학회지
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• 제34권2호
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• pp.221-229
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• 2014

Chicken breast meat was injected with calcium chloride alone and in combination with lactic acid (0.01% and 0.002%, respectively). The inhibitory effects of the treatments on microbial growth were determined in the injected chicken breast meat stored at $4^{\circ}C$ under aerobic packaging condition for 0, 3, and 7 d. Calcium chloride combined with 0.002% and 0.01% lactic acid reduced microbial counts by 0.14 and 1.08 Log CFU/g, respectively, however, calcium chloride alone was unable to inhibit microbial growth. Calcium chloride combined with 0.01% lactic acid was the most effective antimicrobial treatment and resulted in the highest initial redness value. Calcium chloride alone and combined with lactic acid suppressed changes in pH and the Hunter color values during storage. However, injection of calcium chloride and lactic acid had adverse effects on lipid oxidation and sensory characteristics. The higher TBARS values were observed in samples treated with calcium chloride and lactic acid when compared to control over the storage period. Addition of calcium chloride and lactic acid resulted in lower sensory scores for parameters tested, except odor and color, compared to control samples. Therefore, the formulation should be improved in order to overcome such defects prior to industrial application.

• 멤브레인
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• 제16권2호
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• pp.85-105
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• 2006

Poly(lactic acid) (PLA)는 옥수수나 설탕수와 같은 재생자원에서 추출된 환경친화적 재료로서 이에 대한 관심이 증대되고 있다. PLA는 선형 지방족 열가소성 polyester로써, lactide와 lactic acid 모노머의 고리 개환 중합법에 의해 제조된다. PLA는 높은 기계적 능력과 열가소성, 직물능력과 생체적합성을 가지고 있어서, 다양한 end-use application에 유망한 고분자이다. 그러나 열점도, 충격인자, 열변형온도(HDT), gas barrier 특성 등과 같은 다른 몇몇 특성들은 충분히 만족시키지 못한다. 최근에, clay의 실리케이트 층에 용액이나 용융법을 이용한 고분자의 삽입은 순수 고분자나 전형적인 복합체에 비해 기계적, 열적, 광학적, 그리고 물리화학적 특성에서 훌륭한 증진을 꾀할 수 있는 나노복합재료를 제조하기 위한 가장 좋은 기술이다. 층상실리케이트는 자연적으로 풍부하고, 경제적이며, 환경친화적 물질이다. 본 논문에서는 생분해성 고분자를 기초로 한 재생자원 poly(lactic acid)의 여러 합성과 특징, 그리고 그것의 층상실리케이트 나노복합체 분리막으로의 응용과 특징을 알아보고자 하였다.

• Restorative Dentistry and Endodontics
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• 제16권1호
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• pp.87-105
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• 1991

The purpose of this experiment was to measure the leaking and solubility of commonly used dental restorative materials - Silux plus (CS), Hi-pol (CH), Clearfil F-II, Fissureseal (FS), Glass-Ionomer cement Fuji Type II (GI), Amalgam Cavex 68 (AM), Zinc Phosphate Cement (ZP) and gutta-percha (GP) and investigate the relation between the solubility and marginal leakage. Disc-shape specimens were fabricated with each material and dipped into deionized water, 0.01M lactic acid and 0.005M KOH solution, thus the total ionic concentrations in each solution was measured with ion chromatograph after 1, 3, and 7 days, respectively. For the solubility test, each specimen was immersed in 0.001M and 0.01M lactic acid for 24 hours, respectively and total weight loss was calculated. Also, Zn leaking through the margin of restorations was measured. The obtained results were as follows: 1. The amounts of eluted ion from the eight materials were most in 0.01M lactic acid and least in deionized water. 2. Of the eight materials, the fluoride release was greatest for glass ionomer cement (GI) in 0.01 M lactic acid after 7 days. 3. In analysis of the divalent cation, Mg was eluted most for zinc phosphate cement (ZP) and Ca for Clearfil F-II (CF) in 0.01M lactic acid after 7 days. 4. In analysis of transition metals, Cu and Zn were detected only. 5. The solubility rate of eight materials was greater in 0.01M lactic acid than in 0.001M for 24 hours, for zinc phosphate cement (ZP) the rate was greatest (5.4%) in 0.001M lactic acid, and amalgam least (0.01%). 6. The Zn concentration of restorative material with Z.P.C base was greater in 0.01M lactic acid than in 0.001M lactic acid.

• 한국조리학회지
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• 제4권
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• pp.413-436
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• 1998

In order to guarantee the safety of Korean Naeng Myon Broth in summer, pH and micrological quality of iced noodle gravy which is cooked and sold in public restaurant were investigated. And the variations of pH, taste and microorganism were studied with organic acid treatment during storage period. The micrological status of iced noodle gravy showed that average number of total aerobic bacteria was 2.7${\times}$105CFU/$m\ell$ and fecal coliform was 8.3${\times}$103CFU/$m\ell$ respectly. Food poison microorganisms not detected and average of pH was 4.8. pH changed slightly during storage period and deceased with increasement of organic acid added. Sour taste of organic acid increased acetic acid, citric acid, lactic acid order and there was no organic acid having with more sour taste than iced noodle gravy which is cooked and sold in public restaurant. Salmonella was destroyed when treated with 1% of acetic acid and lactic acid and Escherichia coli became extinct at treatment with 0.8% acetic acid and 1% lactic acid. in case of same concentration, inhibition effects to Escherichia coli multiplication show citric acid, lactic acid, acetic acid order. In conclusion, treatment with more than 0.8% acetic acid and above 1.0% lactic acid or more than 1.0% citric acid in case of production and consumption a day can prevent from Escherichia coli pollution in Korean Naeng Myon Broth.

• 한국미생물·생명공학회지
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• 제30권3호
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• pp.241-246
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• 2002

한국 토종닭의 작은창자로부터 살모넬라와 포도상구균치 성장 저해력이 우수한 7주의 유산균을 분리하였다. 분리된 7주의 배양액을 단백질 분해효소로 처리한 결과 저해활성의 변화가 없었다. Lactic acid 1.8 %에 의하여서는 Salmonella gallinarum의 성장저해환이 9 mm 나타났는데 , 대부분의 분리 유산균 배양액은 산도가 1.08∼l.8 %인데도 불구하고 성장 저해환이 10∼ll mm로 나타난 것으로 보아 유산균 배양액내에는 lactic acid이외의 다른 물질이 있는 것으로 사료된다. GC-MSD를 이용하여 항균성이 우수한 L. pentosus K34 배양 액내의 생성된 유기산 metabolic profile을 조사한 결과 28종의 유기산이 검출되었으며, 그 중 천연항균물질인 phenyllactic acid가 lactic acid, acetic acid와 더불어 높은 농도로. 생산되었다. Phenyllactic acid는 acetic acid, formic acid, lactic acid와 저해활성을 비교하였을 때 우수한 항균활성을 보였으며 acetic acid, formic acid, lactic acid가 pH 5.0에서는 저해활성이 크게 감소함에 비하여 phenyllactic acid는 pH 5.0에서도 저해활성이 그대로 유지되었다. Phenyllactic acid는 살모넬라, 포도상 구균에 대한 항균능력이 특이적으로 강력하게 나타났으며 효모, 곰팡이에 대한 항균활성은 매우 낮았다.