• Applied Biological Chemistry
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• 제8권
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• pp.1-9
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• 1967

Korean soy-sauces were orepared by the ordinary and impreved method and its analyses on the organic acid. The results obtained is as following: 1. In analysing general components of prepared soy-sauce, total acid, volatile acid and non-volatile acid were found more in improved soy-sauce than in ordinary soy-sauce. 2. Volatile organic acid were analysed by gas-chromatography method. As a result, the followings was attained: a) In the ordinary soy-sauce, formic acid, acetic acid, propionic acid, and butyric acid were detected. Butyric acid was in the highest amount and then propionic acid, acetic acid and formic acid are followed in the order. b) In the improved soy-sauce, formic acid, acetic acid, propionic acid and butyric acid were detected. Acetic acid was in the highest amount and then propionic acid, butyric acid and formic acid are followed in the nrder. 3. Non-volatile organic acid were analysed by paper partition chromatography method. As a result, the followings were attained: a) Lactic, glutaric, fumaric, malonic, malic, glycolic, oxalic, tartaric, and succinic acid and two unknown spots were detected in ordinary soysauce. Lactic acid was in the highest amount and then succinic, glycolic, oxalic, tartaric, glutaric, malic, fumaric and malonic acid are followed in the order. b) Lactic, glutaric, malonic, malic, glycolic, tartaric, succinic and tgalacturonic acid and two unknown spots were detected in the improved soy-sauce. Lactic acid was in the highest amount and then succinic, glycolic, malic, glutaric, tartaric, galacturonic and malonic acid are followed in the order. 4. ${\alpha}-keto$ acid were analysed by paper partition chromatography. As a result, the followings were attained: Pyruvic acid and ${\alpha}-keto$ glutaric acid and an unknown spot were detected in the ordinary and improved soy-sauce. Pyruvic acid was in the highest amount and then ${\alpha}-keto$ glutaric acid are ollowed in the order. 5. Stale flavor in the ordinary soy-sauces seems to be partly affected by butyric acid and propionic acid. 6. Substances influencing taste, such as lactic acid and succinic acid, were found more in improved soy-sauce than ordinary soy-sauce.

• 한국식품과학회지
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• 제37권6호
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• pp.922-927
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• 2005

한국산 사과의 유기산 분포를 조사하기 위하여 경기도 수원, 강원도 원주, 충남 예산, 경북대구 그리고 전북 정주에서 1997년 가을에 수확한 쓰가루, 후지, 홍옥, 신흥 품종의 완숙과일을 재료로 하여 적정산도, HPLC에 의한 유기산총량과 개별 유기산 그리고 효소법에 따라 L-malic acid를 분석, 고찰하였다. 사과의 적정산도는 172-527mg%으로, HPLC에 의한 유기산 총량 260-739mg%보다 낮았지만 두 값 사이에는 분명한 상관관계가 인정되었다. 품종별 유기산총량은 홍옥 630.80mg%, 신흥의 471.04mg%, 후지 403.80mg% 그리고 쓰가루 364.23mg%의 순으로 품종에 따라 뚜렷한 함량차이를 보였으며 같은 품종이라도 재배지역에 따른 함량차이가 있었다. 유기산 분포는 malic acid 251.01-666.56mg%, quinic acid 7.2-21.49mg%, succinic acid 0-35.37mg%, citric acid 1.81-15.73mg% 그리고 fumaric acid 0.008-0.076mg%이었고 maleic acid는 검출되지 않았다. 구성비율로 보면 malic acid가 94.768%로 가장 많았고, 다음은 quinic acid 2.256%, succinic acid 1.785%, citric acid 1.186%, fumaric acid 0.006% 순이었다. HPLC로 측정한 DL-malic acid 함량에 대한 효소법에 의한 L-malic acid 함량 비율은 평균 1.00(0.98-1.02)으로 그 차이는 무시할 정도로서 품종이나 산지에 따른 차이는 없었다.

• 한국초전도ㆍ저온공학회논문지
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• 제18권1호
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• pp.1-5
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• 2016

Field and temperature dependence of the critical current density, Jc, were measured for both un-doped and carbon doped $MgB_2/Nb/Monel$ wires manufactured by Hyper Tech Research, Inc. In particular, carbon incorporation into the $MgB_2$ structure using malic acid additive and a chemical solution method can be advantageous because of the highly uniform mixing between the carbon and boron powders. At 4.2 K and 10 T, Jc was estimated to be $25,000-25,300Acm^{-2}$ for the wire sintered at $600^{\circ}C$ for 4 hours. The irreversibility field, $B_{irr}$, of the malic acid doped wire was approximately 21.0 - 21.8 T, as obtained from a linear extrapolation of the J-B characteristic. Interestingly enough, the Jc of the malic acid doped sample exceeds $10^5Acm^{-2}$ at 6 T and 4.2 K, which is comparable to that of commercial Nb-Ti wires.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제4권2호
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• pp.95-102
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• 2000

Methane combustion over perovskite-type oxides prepared using the malic acid method was investigated. To enhance the catalytic activity, the perovskite oxides were modified by the substitution of metal into their A or B site. In addition, the reaction conditions, such as the temperature, space velocity, and partial pressure of the methane were varied to understand their effect on the catalytic performance. With the LaCoO3-type catalyst, the partial substitution of Sr or Ba into site A enhanced the catalytic activity in the methane combustion. With the LaBO3(B=Co, Fe, Mn, Cu)-type catalyst, the catalytic activities were exhibited in the order of Co>Fe Mn>Cu. Futhermore, the partial substitution of Co into site B enhanced the catalytic activity, whereas an excess amount of Co decreased the activity. The surface area and catalytic activity of the perovskite catalysts prepared using the malic acid method showed higher values than those prepared using the solid reaction method. The catalytic activity was enhanced with decreased methane concentration and with a decrease in the space velocity.

• 한국대기환경학회지
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• 제14권1호
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• pp.25-33
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• 1998

We have studied the reduction of NO by propane over perovskite-type oxides prepared by malic acid method. The catalysts were modified to enhance the activity by substitution by substitution of metal into A or B site of perovskite oxides. In addition, the reaction conditions, such as temperature, $O_2$ concentration, space velocity have been studed. In the $LaCoO_3$ type catalyst, the partial substitution of Ba, Sr into A site enhanced the catalytic activity in the reduction of NO. In the $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3(x=0 \sim 1.9)$ catalyst, the partial substitution of Fe into B site enhanced the conversion of NO, but excess amount of Fe decreased the conversion of NO. The surface area and catalytic activity of perovskite catalysts prepared by malic acid method showed higher values than those of solid reaction method. In the $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3$ catalyst, the conversion of NO increased with increasing $O_2$ concentration and contact time. The introduction of water into reactant feed decreased the catalytic activity.

• Parasites, Hosts and Diseases
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• 제48권2호
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• pp.127-132
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• 2010

Biomphalaria alexandrina snails play an indispensable role in transmission of schistosomiasis. Infection rates in field populations of snails are routinely determined by cercarial shedding neglecting prepatent snail infections, because of lack of a suitable method for diagnosis. The present study aimed at separation and quantification of oxalic, malic, acetic, pyruvic, and fumaric acids using ion-suppression reversed-phase high performance liquid chromatography (HPLC) to test the potentiality of these acids to be used as diagnostic and therapeutic biomarkers. The assay was done in both hemolymph and digestive gland-gonad complex (DGG) samples in a total of 300 B. alexandrina snails. All of the studied acids in both the hemolymph and tissue samples except for the fumaric acid in hemolymph appeared to be good diagnostic biomarkers as they provide not only a good discrimination between the infected snails from the control but also between the studied stages of infection from each other. The most sensitive discriminating acid was malic acid in hemolymph samples as it showed the highest F-ratio. Using the Z-score, malic acid was found to be a good potential therapeutic biomarker in the prepatency stage, oxalic acid and acetic acid in the stage of patency, and malic acid and acetic acid at 2 weeks after patency. Quantification of carboxylic acids, using HPLC strategy, was fast, easy, and accurate in prediction of infected and uninfected snails and possibly to detect the stage of infection. It seems also useful for detection of the most suitable acids to be used as drug targets.

• 응용화학
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• 제16권1호
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• pp.73-76
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• 2012

Due to the developments of communications equipment and electronic devices, lithium ion secondary battery usage is growing. Along with demand increasing, the amount of scrap has been steadily increasing. In this study, method of cobalt recovery using organic eco-friendly is proposed. Sulfuric acid, Malic acid, Citric acid at reflux device had good cobalt leaching efficiency. And Sulfuric acid, Malic acid at the autoclave increased cobalt leaching efficiency.

• 분석과학
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• 제29권4호
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• pp.202-208
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• 2016

A novel and simple method for detecting seven organic acids (formic acid, malic acid, lactic acid, acetic acid, citric acid, fumaric acid and propionic acid) in animal feed using high performance liquid chromatography equipped with a photo-diode array detector (HPLC/PDA) was developed. The chromatographic peaks of the seven organic acids were successfully identified by comparing their retention times and UV spectra with reference standards. Method validation was performed in terms of linearity, sensitivity, selectivity, accuracy, and precision. The limits of detection (LODs) for the instrument employed in these experiments ranged from 12 to 8,026 μg/kg, and the limits of quantification (LOQs) ranged from 43 to 26,755 μg/kg. Average recoveries of the seven organic acids ranged from 79.3 to 95.2 %. Method replication resulted in intra- day and inter-day peak area variation of <3.2 %. The developed method was specific and reliable and is therefore suitable for the routine analysis of organic acids in animal feed.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1257-1257
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• 2001

Fourier transform near infrared (FT-NIR) spectroscopy was used as a rapid method to measure the $^{o}Brix$ content and to discriminate between different must samples in terms of their fee amino nitrogen (FAN) values. FT-NIR spectroscopy was also used as a rapid method to discriminate between Chardonnay wine samples in terms of the status of the male-lactic fermentation (MLF). This was done by monitoring the conversion of malic to lactic acid and thereby determining whether MLF has started, is underway or has been completed followed by classification of the samples. Furthermore, FT-NIR spectroscopy was applied as a rapid method to discriminate between table wine samples in terms of the ethyl carbamate (EC) content. EC in wine can pose a health threat and need to be monitored by determining the EC content in relation to the regulatory limits set by the authorities. For each of the above mentioned parameters, $QUANT+^{TM}$ methods were built and calibrations derived and it was found that a very strong correlation existed in the sample set for the FT-NIR spectroscopic predictions of $^{o}Brix$ (r = 0.99, SECV = 0.306), but the correlations for the FAN (r = 0.61, SECV = 272.1), malic acid (r = 0.58, SECV = 1.06), lactic acid (r = 0.51, SECV = 1.14) and EC predictions (r = 0.47, SECV = 3.67) were not as good. Soft Independent Modeling by Class Analogy (SIMCA) diagnostics and validation was applied as a sophisticated discrimination method. The must samples could be classified in terms of their FAN values when SIMCA was applied, obtaining results with recognition rates exceeding 80%. When SIMCA diagnostics and validation were applied to determine the progress of conversion of malic to lactic acid and the EC content, again results with recognition rates exceeding 80% were obtained. The evaluation of the applicability of FT-NIR spectroscopy measurement of FAN, $^{o}Brix$ values, malic acid, lactic acid and EC content in must and wine shows considerable promise. FT-NIR spectroscopy has the potential to reduce the analytical times considerably in a range of measurements commonly used during the wine making process. Where conventional FT-NIR calibrations are not effective, SIMCA methods can be used as a discriminative method for rapid classification of samples. SIMCA can replace expensive, time-consuming, quantitative analytical methods, if not completely, at least to some extent, because in many processes it is only needed to know whether a specific cut off point has been reach or not or whether a sample belongs to a certain class or not.

• 생명과학회지
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• 제21권4호
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• pp.509-514
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• 2011

본 연구에서는 참다래를 이용하여 국내산 과실 특유의 강한 산미를 감소시켜 고품질 참다래 와인을 제조하기 위하여 MLF 에 의한 산도 및 malic acid 감소 효과를 연구하였다. MLF가 진행됨에 따라 모든 실험구에서 당도가 점차 감소하는 것으로 나타났으며 $25^{\circ}C$에서 발효한 참다래 와인의 당도가 5.90 $^{\circ}Brix$로 가장 낮게 나타났다. 총산함량은 발효 전 0.96%에서 발효 20일 후 0.75~0.79%로 모든 실험구에서 발효가 진행됨에 따라 총산 함량이 감소하였으나 발효 온도에 따른 유의적 차이는 없었다. 참다래 와인의 malic acid 함량은 MLF가 진행됨에 따라 감소하였으며 $25^{\circ}C$에서 발효시킬 경우 0.05 mg/ml로 가장 낮게 나타났다. 참다래 와인의 초기 pH에 따른 malic acid 함량 변화를 확인한 결과 pH 2.5 실험구에서는 큰 변화를 보이지 않았으며, pH 4.5에서는 발효 완료 시 0.55 mg/ml로 검출되어 약 85% 감소하였다. 또한 초기 pH 3.5로 조절한 실험구는 발효기간이 경과함에 따라 malic acid함량이 급격히 감소하여 발효 완료시 매우 낮게 나타났다. MLF에 의한 malic acid와 lactic acid 함량을 조사한 결과 O. oeni를 첨가하여 MLF를 실시한 실험구의 malic acid는 급격히 감소하여 14일 후에 0.08 mg/ml로 나타났으며 lactic acid의 함량은 점점 증가하여 발효 16일에 3.15 mg/ml로 나타났다. 초기 pH를 3.5로 조절하고 $25^{\circ}C$에서 15일간 발효시킨 참다래 와인의 품질특성을 조사한 결과 총산 함량은 0.78%로 대조구의 0.96%보다 다소 낮게 나타났으며 pH는 3.70로 MLF를 실시하지 않은 대조구의 3.45 보다 높게 나타났다. 또한 알코올 함량은 12.75%, 총당 38.72 mg/ml, 총폴리페놀 60.18 mg/ml로 대부분 큰 차이는 보이지 않았다. Oxalic acid는 0.69 mg/ml로 대조구와 유사하게 나타났으며 강한 신맛을 내는 malic acid는 대조구에 비해 크게 감소하여 0.06 mg/ml로 나타났다. 반면 lactic acid는 대조구보다 4.5배 많은 3.12 mg/ml로 나타났고 citric acid는 대조구와 유사한 0.26 mg/ml로 나타났다. 관능평가 결과 MLF를 실시한 와인이 대조구 와인에 비해 떫은맛을 제외한 모든 부분에서 우수한 것으로 나타났으며, 특히 신맛과 전체적 기호도에서 $3.8{\pm}0.5$와 $3.9{\pm}04$로 대조구의 $3.5{\pm}0.6$과 $3.5{\pm}0.5$보다 높게 나타났다. 결과적으로 고품질의 참다래 와인을 제조하기 위한 MLF의 최적 조건은 초기pH 3.5로 조절한 후 MLF 균주인 O. oeni ($1{\times}10^6$ CFU/ml)를 첨가하여 $25^{\circ}C$에서 발효시키는 것이 가장 적합할 것으로 생각된다.