• Journal of the Korean Society of Food Culture
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• v.13 no.3
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• pp.191-196
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• 1998

The influence of organic acid dips on the quality properties, color, cooking quality, textural and sensory properties, and reducing microbial population of LL(Long Life) noodles was studied. The contents of organic acid used were 0.2% based on flour weight and LL noodles were treated by dipping in pH $2.5{\pm}0.1$ for $60{\sim}90sec$. The whiteness of LL noodles treated with dl-malic acid was higher than that of others. The shear extrusion force and hardness of LL noodles treated with dl-malic acid were shown much higher value than those of others except treated with dl-malic acid. acetic acid(=1:1). At cooking quality examination of LL noodles treated with organic acids, weight of cooked LL noodles treated with dl-malic acid was decrease but volume was appeared in vice versa. Extraction amounts of LL noodles treated with dl-malic acid, dl-malic acid : acetic acid(=1:1) during cooking were much smaller than those of others. Total counts of microorganism of LL noodles treated with dl-malic acid,dl-malic acid. acetic acid(=1:1) were disappeared during storage at $30^{\circ}C$ but treated with latic acid, acetic acid were increase during storage. Sensory properties of cooked LL noodles which was treated with dl-malic acid showed quite acceptable.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.922-927
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• 2005

Total and individual organic acid contents of Malus domestica Borkh, cultivars, Tsugaru, Fuji Jonathan (Hong-Ok), and New Jonagold(Sin-Heung) apples, were investigated. Average titratable acidities measured by titration method and total organic acids content determined by HPLC were 241.64-444.52 and 364.23-680.80mg%, respectively. Average total organic acid contents were Jonathan 630.80mg%, New Jonagold 471.04mg%, Fuji 403.80mg%, and Tsugaru 364.23mg%, Contents of DL-malic, citric, fumaric, and quinic acid were 351.98 (Tsugaru)-579.88mg% (Jonathan), 2.14 (Fuji)-12.95mg% (Jonathan), 0.012 (Fuji)-0.060mg% (Jonathan), and 8.91 (Tsugaru)-14.20mg% (Fuji), respectively. Succinic acid was detected only from Jonathan (27.53mg%) and New Jonagold (5.20mg%), while maleic acid was not detected from all cultivars. Ratio of L-malic acid and DL-malic acid contents were 0.98-1.02 in all apple cultivars.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.2
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• pp.181-187
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• 2000

The contents of organic acid in Korean apple juice were analyzed by HPLC using YMC-peak ODS-AQ column and enzymatic assay. Model apple juices were prepared at the laboratory and commercial apple juices were purchased from the market. Individual organic acid contents were as follows: DL-malic acid 62~402mg%, L-malic acid 48~360mg%, citric acid 1.81~15.74mg%, fumaric acid nd~0.50mg%. Together, these tests gave useful information about the quality and authenticity of a particular apple juice smaple. The presence of D-malic acid was a clear indication of adulteration because this isomer did not occur naturally. Fumaric acid and citric acid levels above trace amounts were also inconsistent with pure apple juice.

• The Korean Journal of Food And Nutrition
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• v.11 no.3
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• pp.278-282
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• 1998

An attempt was made in this study to investigate the possibility of processing fresh garlic into an fresh garlic paste. The characteristics of fresh garlic paste and processing properties were investigated and the effect of salt, maltodextrin, acid and heat on product quality during storage were studied. After the processed fresh garlic paste was stored at 3$0^{\circ}C$ and 5$^{\circ}C$ without light for 6 months. The weight and pH of colve were 93% of total and 5.95, respectively. Addition of 10% salt, 10% maltodextrin, 01.% dl-malic acid, and heat on fresh garlic paste maintain color of fresh garlic could be preserved for 6 months at 5$^{\circ}C$. Judging from thiosulfinate and pyruvate content, and sensory evaluation, quality damage of fresh garlic paste which was make of 10% salt, 10% maltodextrin, 0.1% dl-malic acid, and heat on fresh garlic paste hardly occurred at 5$^{\circ}C$ but occurred considerable level at 3$0^{\circ}C$ during storage for 6 months.

• Resources Recycling
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• v.23 no.4
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• pp.21-29
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• 2014

Nickel, cobalt and manganese-based(NCM, $Li(Ni_xCo_yMn_z)O_2$) cathode active materials of spent lithium-ion batteries contained valuable metals such as cobalt(15 ~ 20%), nickel(25 ~ 30%), manganese(10 ~ 15%) and lithium(5 ~ 10%). It was investigated the eco-friendly leaching process for the recovery of valuable metal from spent lithium-ion battery NCM cathode active materials by DL-malic acid($C_4H_5O_6$) as an organic leachant in this research. The experiments were carried out to optimize the process parameters for the recovery of cobalt, nickel and lithium by varying the concentration of lixivant, reductant concentration, solid/liquid ratio and temperature. The leaching solution was analyzed using ICP-OES(Inductively Coupled Plasma Optic Emission Spectrometer). Cathode active materials of 5 wt. % were introduced into the leaching solution which was 2 M DL-malic acid in addition of 5 vol. % $H_2O_2$ at $80^{\circ}C$ and it resulted in the recovery of 99.10% cobalt, 99.80% nickel and 99.75% lithium in 120 min. $H_2O_2$ in DL-malic acid solution acts as an effective reducing agents, which enhance the leaching of metals.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2162-2166
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• 2013

The tailored surface modification of electrode materials is crucial to realize the wanted electronic and electrochemical properties. In this regard, a dexterous carbon encapsulation technique can be one of the most essential preparation methods for the electrode materials for lithium rechargeable batteries. For this purpose, DL-malic acid ($C_4H_6O_5$) was here used as the carbon source enabling an amorphous carbon layer to be formed on the surface of Si nanoparticles at enough low temperature to maintain their own physical or chemical properties. Various structural characterizations proved that the bulk structure of Si doesn't undergo any discernible change except for the evolution of C-C bond attributed to the formed carbon layer on the surface of Si. The improved electrochemical performance of the carbon-encapsulated Si compared to Si can be attributed to the enhanced electrical conductivity by the surface carbon layer as well as its role as a buffering agent to absorb the volume expansion of Si during lithiation and delithiation.

• The Korean Journal of Food And Nutrition
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• v.11 no.2
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• pp.216-220
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• 1998

To maintain flavor and color of fresh green pepper, the fresh green pepper paste was directly prepared from fresh green pepper. The characteristic of fresh green pepper paste and processing properties were investigated, and the effect of salt, glucose, acid and heat on product quality during processing and storage were studied. After the processed fresh green pepper paste was stored at 3$0^{\circ}C$ and 5$^{\circ}C$ without light for 6 months. The weight and pH of pericarp were 86% of total and 4.5~5.0, respectively. Addition of 10% salt, 5% glucose, and 0.1 dl-malic acid to the fresh green pepper paste maintain flavor of fresh green pepper could be preserved for 6 months at 5$^{\circ}C$. Panel test showed fresh green pepper paste which was made of 10% salt, 5% glucose and 0.1% dl-malic acid to the fresh green pepper was quite acceptable.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.199.2-199
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• 2003

제주민속주인 좁쌀약주의 제조를 위하여 전국에서 수집된 35종의 누룩으로부터 분리하여 선발한 균주를 사용하여 균주와 원료배합비율에 따른 누룩을 제조한 후 양조과정에서의 발효특성을 검토하였다. 좁쌀주의 유기산 및 유리당의 분석결과 유기산은 lactic acid와 acetic acid가 대부분이었고, 이외에 citric acid, oxalic acid, tartaric acid, malic acid, fumaric acid도 일부 검출되었다. 유리당은 glucose와 arabinose, maltose가 많은 함량을 나타내었고, 이외에 xylose도 일부에서 검출되었다. 향기성분은 i-amyl alcohol, i-butyl alcohol, n-propyl alcohol 등이 주를 이루고 있었으며, 이외에 ethylacetate, acetaldehyde가 검출되었다. i-buthyl alcohol과 n-propyl alcohol은 대조구인 Dl이 다른 처리구보다 높게 나타났고, i-amyl alcohol은 K5 처리구가 높게 나타났다. 본 연구를 통하여 우수균주로 분리하여 제조한 누룩을 사용하여 좁쌀주를 양조하는 경우, 품질을 유지하면서 수율을 향상시킬 수 있었다.

• Journal of Mushroom
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• v.10 no.2
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• pp.83-92
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• 2012

To provide a basis for the variation of fruit bodies of winter mushroom (Flammulina velutipes), the organic acid composition of its fruit bodies was investigated with several varieties of winter mushroom indifferent temperature and storage period. In the fruit bodies of winter mushroom, a total of 10 organic acids including acetic acid, butyric acid, citric acid, fumaric acid, DL-isocitric acid, L(+)lactic acid, D-malic acid, propionic acid, succinic acid, and D-tartaric acid were detected. In the most of the winter mushroom, acetic acid was the main organic acid component and fumaric acid was the least included component. Acetic acid, which is a mono-carboxyl group of organic acid, is contained in different levels according to different varieties and different storage temperature. Butyric acid is extremely variable in its quantity, depending on variety and different storage temperature. In contrast, fumaric acid, which is a dicarboxyl group of organic acid, decreased in its quantity during storage with 1.5 mg/g. Especially, ASI 4149, 4166 varieties tend to differ in their quantity. Besides, malic acid is extremely variable in its quantity according to variety and storage temperature. Citric acid, a tri-carboxyl group of organic acid, increased in its quantity according to storage period, which enables us to efficiently manage storage period. Isocitric acid is also extremely variable in its quantity according to variety, storage temperature and storage period.

• Journal of agriculture & life science
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• v.44 no.5
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• pp.81-90
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• 2010

This study was conducted to evaluate quality characteristics of citron from Namhae. The physicochemical properties, organic acid, free sugar and aroma components were analyzed and compared with citron harvested in different areas of Namhae (Seolcheon, Changseon and Idong-meyon). Total weight of citron was range of 120.51~176.56 g, total and peel weight of citron cultivated from Changseon were significantly higher than the other citron. The color of peel was not significant in cultivated area. Soluble solids was higher in citron from Changseon and Idong than Seolcheon. Total phenol and flavonoids contents in citron from Idong were higher than the others. Organic acids such as citric acid and malic acid were higher in citron from Changseon. The contents of fructose and glucose in peel and sucrose in pulp were detected higher amount. Major component of aroma profiles in citron from different region of was dl-limonene. It was amount to 57.60% in citron from Idong, 71.02% and 73.04% in citron from Seolcheon and Changseon of all aromatic components. These results were suggested that physicochemical properties and aroma components of citron have some difference by cultivation habit, period, different cultivar and producing areas.