• 제목/요약/키워드: citric acid

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Citric acid 조성 비율에 따른 식각 특성에 관한 연구 (Studies on Wet Etching of PHEMT with Citric acid based solutions)

  • 설우석;이복형;김성찬;이성대;김삼동;신동훈;이진구
    • 대한전자공학회:학술대회논문집
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    • pp.33-36
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    • 2001
  • In this paper, we have studied the characteristics of wet etching using citric acid based wet etchant. We have used the citric acid / hydrogen peroxide solution, citric acid / hydrogen peroxide / D.I. water solution. From our experimental result, a volumetric 1:3 ratio of citric acid and hydrogen peroxide and 1 : 3 : 1 ratio of citric acid, hydrogen peroxide, and D.I. water is shown to be a better wet etchant of PHEMT's system.

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Aspergillus niger를 이용한 유청으로부터 구연산의 생산에 있어서 온도와 pH의 영향 (Effects of Temperature and pH on the Production of Citric Acid from Cheese Whey by Aspergillus niger)

  • 이정훈;윤현식
    • 한국균학회지
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    • v.27 no.6
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    • pp.383-385
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    • 1999
  • Cheese 제조시 부산물로 생성되는 whey를 배지로 사용하여 Aspergillus niger를 이용하여 citric acid를 생산하는데 영향을 미치는 여러 가지 요인 중 중요한 요인인 온도와 pH의 영향에 대하여 고찰하였다 15일간 27, 30, 33, $36^{\circ}C$와 pH 2, 3, 4, 5에서 각각 배양하면서 소비된 lactose의 양과 생산된 citric acid의 양을 측정하였다. 생산된 citric acid의 최대 농도는 33.9 g/l(구연산 생산에 쓰여진 유당을 기준으로 할 때 68.26%)이었으며, shaking speed는 citric acid 생산에 직접 영향을 주기보다는 pellet 형성시 그 형태에 영향을 미치는 것으로 나타났다. 배양 온도가 $33^{\circ}C$, pH는 3일때 가장 많은 양의 citric acid가 생산되었다.

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밀감양조주 생산용 효모의 선별, 동정 및 Citric Acid 분해 (Screening and Identification of the Yeasts for Orange Wine and Their Citric Acid Decomposition)

  • 고영환;김재하;고정삼;김창진
    • 한국식품과학회지
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    • v.29 no.3
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    • pp.588-594
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    • 1997
  • 제주산 온주밀감(Citrus unshiu)을 이용한 양조주를 제조하는데 적합한 효모를 선별하고, 밀감양조주의 품질에 직접적으로 연관된 효모의 citric acid 분해능에 대해서 기초조사를 실시하였다. 밀감양조주용으로 활용가능하다고 판단된 균주는 모두 11주이었다. 제주지역의 토양을 중심으로 5개의 효모균주를 분리, 선별하였는데, 그중 4개 주는 Saccharomyces cerevisiae, 나머지 1개 주는 S. ellipsoideus로 동정되었다. 한편 분양 균주 18주 중에서 선별된 균주는 6개 주로, S. cerevisiae 계통의 3개 주와 S. coreanus, S. uvarum, S. sake 각각 1개 주었다. 이중에서 S. cerevisiae 2개 균주의 citric acid 분해능을 조사하였다. Citric acid는 효모의 유일한 탄소원으로는 이용될 수 없었으나, citric acid가 glucose와 함께 탄소원으로 사용되었을 때, 배양액 중의 citric acid 농도는 감소하였으며, 정치배양 보다 진탕배양하였을 때 더 많이 감소하였다. 효모에 의한 citric acid의 이용은 ethanol 농도를 증가시키지 못하였으며, 오히려 citric acid는 효모의 생육을 부분적으로 저해하였다.

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Bonding Performance of Maltodextrin and Citric Acid for Particleboard Made From Nipa Fronds

  • Santoso, Mahdi;Widyorini, Ragil;Prayitno, Tibertius Agus;Sulistyo, Joko
    • 목재공학
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    • v.45 no.4
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    • pp.432-443
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    • 2017
  • Maltodextrin and citric acid are two types of natural materials with the potential as an eco-friendly binder. Maltodextrin is a natural substance rich in hydroxyl groups and can form hydrogen bonds with lignoselulosic material, while citric acid is a polycarboxylic acid which can form an ester bond with a hydroxyl group at lignoselulosic material. The combination of maltodextrin and citric acid as a natural binder materials supposed to be increase the ester bonds formed within the particleboard. This research determined to investigate the bonding properties of a new adhesive composed of maltodextrin/citric acid for nipa frond particleboard. Maltodextrin and citric acid were dissolved in distillated water at the ratios of 100/0, 87.5/12.5, 75/25 and 0/100, and the concentration of the solution was adjusted to 50% for maltodextrin and 60% citric acid (wt%). This adhesive solution was sprayed onto the particles at 20% resin content based on the weight of oven dried particles. Particleboards with a size of $25{\times}25{\times}1cm$, a target density $800kg/m^3$ were prepared by hot-pressing at press temperatures of $180^{\circ}C$ or $200^{\circ}C$, a press time of 10 minute and board pressure 3.6 MPa. Physical and mechanical properties of particleboard were tested by a standard method (JIS A 5908). The results showed that added citric acid level in maltodextrin/citric acid composition and hot-pressing temperature had affected to the properties of particleboard. The optimum properties of the board were achieved at a pressing temperature of $180^{\circ}C$ and the addition of only 20% citric acid. The results also indicated that the peak intensity of C=O group increased and OH group decreased with the addition of citric acid and an increase in the pressing temperature, suggesting an interreaction between the hydroxyl groups from the lignocellulosic materials and carboxyl groups from citric acid to form the ester groups.

Optimization of Citric Acid Production by Immobilized Cells of Novel Yeast Isolates

  • Hesham, Abd El-Latif;Mostafa, Yasser S.;AlSharqi, Laila Essa Omar
    • Mycobiology
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    • v.48 no.2
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    • pp.122-132
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    • 2020
  • Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ~52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 ℃, with NH4Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 ℃ with (NH4)2 SO4 as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.

Citric Acid 처리가 모시직물의 주름 회복성과 기계적 성질에 미치는 영향 (Effect of Citric Acid Treatment on Wrinkle Recovery and Mechanical Properties of Ramie Fabrics)

  • 정유진;박종신
    • 한국섬유공학회지
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    • v.35 no.9
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    • pp.584-591
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    • 1998
  • Citric acid was used to improve the wrinkle recovery of ramie fabrics. The effect of curing conditions, citric acid concentration, and triethanolamine (TEA) amount on the wrinkle recovery of the fabrics were investigated. The wrinkle recovery increased with the curing time, curing temperature, and citric acid concentration and changed little up to 5% of TEA amount but decreased afterwards. FT-IR was used to study the degree of reaction between ramie cellulose and citric acid. Ester carbonyl band absorbance ratio and carbonyl band intensity ratio showed that the ester crosslinking increased with the curing time, curing temperature, and citric acid concentration and changed little up to 5% of TEA amount but decreased afterwards. The mechanical properties of treated fabrics such as breaking strength, tearing strength, and abrasion resistance were also investigated. The mechanical properties were deteriorated seriously with the citric acid treatment. One reason for the deterioration could be uneven distribution of crosslinking due to some structural characteristics such as nodes in ramie fibers. The deterioration of mechanical properties, however, could be prevented to a certain degree by using TEA.

Citric acid-water 혼합시스템에서 $Sr_{2+}$의 흡착특성 (Sorption Kinetics of $Sr_{2+}$in Citric Acid-Water systems)

  • 김계남;김진완;한운우;원휘준;오원진
    • 한국지하수토양환경학회:학술대회논문집
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    • pp.133-136
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    • 2000
  • Soil decontamination process was conducted to study adsorption and modeling characteristic of Sr$^{2+}$ ion using citric acid and water system with TRIGA soil. When the concentration of citric acid was increased, the BTC of Sr$^{2+}$ ion was to be closed to the BTC of $^3$$H_2O$ at experiments of soil adsorption. Beside, when the concentration of citric acid was under 0.01M Sr$^{2+}$ ion, BTLs was asymmetry. It was characteristic of nonequilibrium adsorption. R and $K_{p}$ , were decreased to be increased the concentration of citric acid. Asymmetry modeling was nearly the same to be compare with symmetry modeling in decontamination process, when the concentration of citric acid was decreased. Result of experiment was agree with asymmetry and symmetry model, when the concentration of citric acid was increased.eased.

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파일럿 규모의 실증실험 사례를 통한 구연산의 우라늄 식물 전이 효과 규명 (The Investigation for the Effects of Citric Acid on the Uranium Transfer into the Plants by the Pilot Scale Feasibility Test)

  • 한이경;이민희
    • 한국지하수토양환경학회지:지하수토양환경
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    • v.21 no.6
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    • pp.146-155
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    • 2016
  • The field feasibility tests for a phytoextraction process were performed to identify the effect of citric acid as a chelate on the uranium (U) transfer into the plant for the naturally U contaminated soil in Duckpyeongri, Korea. For the feasibility tests, lettuce and Chinese cabbage were cultivated for 49 days on four testing grounds ($1m{\times}1m{\times}0.5m$ in each) in 2016. The citric acid solution was added to two testing grounds (one for lettuce and the other for Chinese cabbage) increasing the U transfer in two crop plants and their results were compared to those without the citric acid solution. When without the citric acid solution, the U concentration of plant after the cultivation was low (< $45{\mu}g/kg$ for leaves and < $450{\mu}g/kg$ for roots). However, with the addition of 50 mM citric acid solution, the U concentration of lettuce leaves and roots increased by 24 times and 1.8 times, and the U concentration of Chinese cabbage leaves and roots increased by 86.7 times and 5.4 times. The absolute accumulated U amount (${\mu}g$) in lettuce and Chinese cabbage also increased by 8.7 times and 50 times, compared to those without citric acid solution. Less than 8% of the U amount of exchangeable/carbonate phases was removed by using the lettuce and Chinese cabbage when the citric acid solution was not applied. However 52% and 66% of the U amount in exchangeable/carbonate phases were removed by the lettuce and the Chinese cabbage when the citric acid solution was added. The effect of the citric acid on the U transfer capability into the plants was quantitatively investigated by the field feasibility test, suggesting that U existing as exchangeable/carbonate phase in soil can be successfully removed by the phytoextraction process using Chinese cabbage with citric acid.

다진 생강의 저장성 증진에 관한 연구 (Improvement of Quality and Prolongation in Chopped Ginger Storage)

  • 이상복;김명숙;최윤희
    • Applied Biological Chemistry
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    • v.40 no.2
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    • pp.123-127
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    • 1997
  • 다진 생강의 저장성을 향상시키고자 다진 생강에 citric acid $0.5{\sim}2.0%$처리는 초기 pH $3.1{\sim}4.6$으로 8개월 후에도 대체로 양호하였으며, citric acid 0.5% 처리의 polyphenol oxidase (PPO) 활성은 NaCl 5.0%나 ascorbic acid 0.5%처리보다 낮았고 항산화제인 ascorbic acid는 citric acid에 비하여 쉽게 변질되었다. NaCl(5.0%)+citric acid(0.5%)나 NaCl(5.0%)+citric acid(1.0%)의 혼합처리로 NaCl 5.0% 단일처리에 비하여 pH 및 PPO활성이 낮아 졌으며 12개월 경과 후에도 양호하였고, NaCl(5.0%)+ascorbic acid(0.5%)처리는 NaCl(5.0%)+citric acid(0.5%)처리와 비교하여 pH에는 큰 차이가 없었으며 4개월째 PPO활성이 급격히 증가하여 무처리보다도 높았으나 변질되지 않았다. 또한 NaCl+citric acid+ascorbic acid의 세 가지 혼합처리 중 5.0%+0.1%+0.1%, 5.0%+0.25%+0.1%, 5.0%+0.5%+0.1% 등의 처리는 8개월 저장시까지 대체로 양호하였으나 그 이후에는 변색이나 이취가 발생되어 장기보존에는 5.0%+0.5%+0.25%처리가 보다 효과적 이었다.

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Citric Acid 첨가에 의한 Hydroxyapatite 나노입자 함유 키토산 필름의 제조 (Preparation of Chitosan Films Containing Hydroxyapatite Nanoparticle by Citric Acid Addition)

  • 정용식;최충열;이근완;좌용호;박병기
    • 한국섬유공학회지
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    • v.39 no.4
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    • pp.383-389
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    • 2002
  • Nano-structured hydroxyapatite(HAp)/chitosan composites and their transparent films were prepared by the co-precipitation and solvent casting method. According to TEM observation, HAp particles with 100~150nm in length and 10~20nm in width were formed in the composites. We investigated the role of citric acid in the HAp/chitosan film formation. The HAp/chitosan films were prepared at various concentrations of citric acid. HAp particles did not aggregate in the chitosan matrix above 50% citric acid concentration for the HAp content. The inhibition effects result from the adsorption of citric acid on the surface of HAp particles by ionic exchange of phosphate ions with citrate ions at the HAp/chitosan composite solution, which is caused by a higher affinity of citrate than phosphate species for the Ca-site on the HAp surface.