• KSBB Journal
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• v.9 no.4
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• pp.406-411
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• 1994

An extractive fermentation process was developed to produce citric acid from g1ucose. Citric acid is a strong inhibitor to this fermentation. A mixture of tertiary amine and oleyl alcohol was used to selectively extract citric acid from the fermentation broth, hence enhancing the productivity by over 200%. Although the toxicity of the solvent was significant in the range of higher than 30% of amine, immobilization in polyurethane foam was useful to protect the cells from the toxicity of the solvent.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.874-878
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• 2012

In the submerged fermentation of fungi, it was known pH had significant effect on the citric acid production. Various growth conditions were applied with different buffer on citric acid production by Aspergillus niger NRRL 567 grown on peat moss to find the optimum pH and most effective buffer solution. The initial pHs of different buffer solutions significantly influenced on the citric acid production and A. niger NRRL 567 produced citric acid more efficiently at high pHs. A phosphate buffer and a carbonate buffer with pH 8.6 and pH 10.0 were identified as suitable buffer solutions for citric acid production. The maximal citric acid production of 564.3 g/kg solid substrate was achieved employing carbonate buffer at pH 10.0.

• Journal of Periodontal and Implant Science
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• v.24 no.1
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• pp.26-38
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• 1994

The purpose of this study was to evaluate the effects of citric acid and fibrin on the regeneration of periodontal tissues using 4 normal canines of five dogs. Mucoperiosteal flap was raised and experimental defects were made at the buccal root surfaces about $4{\times}6mm$ in length. The denuded root surfaces were covered using coronally repositioning technique after root planing alone at left lower canine, root planing plus fibrin at rigth lower canine, root planing plus citric acid at left upper canine or root planning plus citric acid and fibrin at right upper canine. All of the specimens were tangentially cut(about $3-5{\mu}m$)and available for histologic analysis 1, 3, 7, 14 and 21 days after operations. The results were as follows : At one' day after operations, the amounts of fibrin were similarly higher in the group I, II and III than control group and at 3 days after operations, the apical migrations of the long junctional epithelium were prominent in the control group and group I. At 7 days after operations, the fibrin meshworks of each group were partly changed to the collagen fibers and characteristics of the fibers were almost collagenous rather than fibrinous at 14 days after operations and at 21 days after operations, the orientation of collagen fibers were partly normal in group II and group III, but not in control group and group I. Root resorptions were visible in group II and group III at 14 days after operations and more significant in group II than group III at 21 days.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1975.12a
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• pp.182.2-182
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• 1975

자연계에서 분리한 유기산 생성균 8주 가운데 구연산 생성능력이 강한 1주를 선정하여 이것이 Aspergillus niger임을 확인하였다. 이 균주를 Sakaguchi's medium 으로 14일 동안 진 탕배양함으로써 17g/l의 구연산이 생산되어, 같은 조건에서 12g/l를 생성하는 기존 균주 A. usamii보다 구연산 생성율이 높았으므로 이 A. niger 사용 균주로 결정하였다.(중략)

• Korean journal of food and cookery science
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• v.19 no.6
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• pp.777-782
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• 2003

This study was carried out to investigate the characteristics of mulberry fruit seolgidduk. Four percent additions of mulberry were evaluated as the most suitable concentration for seolgidduk, in order to improve the color of gum metal gray and sour smell. Therefore, in order to improve the preference, citric acid was added. The acidity of mulberry fruit seolgidduk increased and its pH decreased significantly by increasing the amount of citric acid. The moisture content of mulberry fruit seolgidduk showed no significant difference between the groups with added citric acid and the control group. The L value decreased as the citric acid concentration increased. Color a and b (Ed-define 'a' and 'b') values increased significantly by increasing the mont of citric acid. The hardness, cohesiveness, springiness, gumminess and brittleness decreased as the citric acid was added. From the sensory evaluation, mulberry fruit seolgidduk with 0.01％ citric acid added was the most preferred in taste, chewiness and overall acceptability. These results indicated that mulberry fruit stolgidduk with 0.01％ citric acid added showed the best quality.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.879-884
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• 2012

In this present study, Aspergillus niger NRRL 567 was cultivated on an inert support material and the effects of various fermentation parameters including temperature, nutrient solution pH, inoculation level, and moisture content were observed and optimized by one-factor-at-a-time (OFAT) and response surface methodology (RSM), sequentially. It was found that the incubation temperature of $30^{\circ}C$ with 75% moisture content, nutrient solution pH of 7.1 and inoculation level of $4.0{\times}10^6$ spores/ml were the most favorable. Again, fermentation parameters were optimized using RSM. The determined optimum condition is $26.5^{\circ}C$, pH 9.9, 75.1%, and $6.0{\times}10^6$ spores/ml. Under this optimized condition, A. niger NRRL 567 produced 118.8 g citric acid/kg dry peat moss at 72 hr. Maximum citric acid production of optimized condition by RSM represented a 1.6-fold increase compared to that obtained from control experiment.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.104.1-104.1
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• 2013

스테인레스강 진공용기의 기체방출률을 낮추기 위해 구연산을 사용하여 화학세척한 후 진공 중 산화처리(VTO)하였다. 1E-11 mbar 이하의 극고진공에 도달하기 위해서는 진공펌프의 성능 뿐 아니라 진공 용기 자체로부터 지속적으로 방출되는 수소의 양을 줄이는 것이 중요하다. 스테인레스 강의 경우 잘 형성된 표면의 크롬산화막이 수소 방출을 억제하는데 효과가 있다고 알려져 있다. 구연산은 스테인레스 강의 표면 철 성분을 감소시키므로 상대적으로 크롬 비율을 증가한다. 이렇게 표면의 크롬 비율이 증가한 상태로 VTO 처리하면 보다 순수하고 균일한 크롬산화막이 형성될 것으로 기대할 수 있다. 본 발표에서는 구연산 +VTO 처리한 스테인레스 강(SST304) 진공 용기의 기체방출률 측정결과에 대해 논의하고자 한다.

• Journal of Life Science
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• v.6 no.1
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• pp.6-13
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• 1996

The possible use of milk-wastewater as a fermentation media for the production of citric acid by Aspergillus niger has been investigated. The addition of Mn$^{2+}$ , Fe$^{2+}$ and Cu$^{2+}$ to the medium promoted citric acid production while only Mg$^{2+}$ decreased citric acid production. The concentrations of citric acid produced were marked up to 7.2g/l and 16.5g/l in a batch bioreactor by Aspergillus niger ATCC 9142 with 50g/l and 100g/l of reducing sugar concentration in milk-wastewater, respectively. A mathematical model was developed and simulating the predictability of cell growth, citric acid production and substrate consumption rate, and gave good agreement results with experimental data.

• KSBB Journal
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• v.25 no.5
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• pp.443-448
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• 2010

Coated citric acid as an acidulant was prepared to be used as a stable food additive. Sensory evaluation of chocolate products with the coated acidulant additive was performed to improve sensory preference tendency in chocolate product. When the ratio of coated acidulant was varied on the preparation of dark (0, 1, 2 wt%), milk (0, 1, 2 wt%) and white (0, 2, 4, 6 wt%) chocolate, 1 wt% (dark and milk) or 2 wt% (white) addition showed better preference than that of 0% sample in overall acceptability. Under the condition of the same coated acidulant content (1% or 2%), the white chocolate showed best sensory evaluation result in sweet, sour taste and overall acceptability.

• Microbiology and Biotechnology Letters
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• v.13 no.3
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• pp.245-250
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• 1985

In order to increase citric acid productivity. several attempts were made; isolation and characterization of the mutant strain produced citric acid in a high yield, citric acid fermentation in a medium containing relatively higher amount of glucose and citric acid production by the use of semicontinuous ceil recycle system. By the treatment of Candide lipolytica S-109 with NTG, a mutant J-24 was selected as the highest producer of citric acid among the strains formed larger CaCO$_3$ lytic zone. it produced 72g/1 citric acid in 10％ glucose medium. Because mutant J-24 produced 85g/l citric acid and showed 53％ yield in 16％ glucose medium, several factors were adjusted to increase the yield in 16％ glucose medium. 0.8-1.0$\times$10$^{-3}$ P/C ratio, 0.15％ urea, 0.25％ yeast extract were suitable at citric acid production in 16％ glucose medium. Under this condition, J-24 strain produced 93g/l citric acid and showed 58％ yield. Semicontinuous cell recycle system was used to protons the effective production phase, to minimize the product inhibition and to shorten the lag phase. The productivity of semicontinuous cell recycle system was 0.79g/l h while that of batch system was 0.53g/l.h