• 한국환경과학회지
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• 제27권12호
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• pp.1205-1214
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• 2018

During the past few decades, significant increase in the consumption of coffee has led to rapid increase in the production of coffee waste in South Korea. Spent coffee waste is often treated as a general waste and is directly disposed without the necessary treatment. Spent Coffee Grounds (SCGs) can release several organic contaminants, including caffeine. In this study, leaching tests were conducted for SCGs and oxidative degradation of caffeine were also conducted. The tested SCGs contained approximately 4.4 mg caffeine per gram of coffee waste. Results from the leaching tests show that approximately 90% of the caffeine can be extracted at each step during sequential extraction. Advanced oxidation methods for the degradation of caffeine, such as $UV/H_2O_2$, photo-Fenton reaction, and $UV/O_3$, were tested. UV radiation has a limited effect on the degradation of caffeine. In particular, UV-A and UV-B radiations present in sunlight cause marginal degradation, thereby indicating that natural degradation of caffeine is minimal. However, $O_3$ can cause rapid degradation of caffeine, and the values of pseudo-first order rate constants were found to be ranging from $0.817min^{-1}$ to $1.506min^{-1}$ when the ozone generation rate was $37.1g/m^3$. Additionally, the degradation rate of caffeine is dependent on the wavelength of irradiation.

• 한국식품과학회지
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• 제24권3호
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• pp.215-220
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• 1992

Caffeine을 기질로 이용할 수 있는 균을 토양과 폐수에서 7종을 분리하고 그중 카페인 분해능이 가장 좋은 KS-5를 동정하여 Pseudomonas putida KS-5라고 명명하였다. P. putida KS-5의 생장 최적조건은 온도 $30^{\circ}C$, pH 7.0이었고 카페인 농도는 1.0%였다. P. putida KS-5는 plasmid DNA가 존재하였으며, 카페인 분해유전자가 plasmid에 존재할 수 있음을 알 수 있었다. 한편 이들 분해유전자의 유전적 특징을 규명하기 위한 curing test와 transformation에 필요한 marker를 찾아본 결과 각종 항생물질에 대하여 내성이 있었다.

• Journal of Microbiology and Biotechnology
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• 제28권7호
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• pp.1147-1155
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• 2018

The degradation efficiency and catabolism pathways of the different methylxanthines (MXs) in isolated caffeine-tolerant strain Pseudomonas putida CT25 were comprehensively studied. The results showed that the degradation efficiency of various MXs varied with the number and position of the methyl groups on the molecule (i.e., xanthine > 7-methylxanthine ${\approx}$ theobromine > caffeine > theophylline > 1-methylxanthine). Multiple MX catabolism pathways coexisted in strain CT25, and a different pathway would be triggered by various MXs. Demethylation dominated in the degradation of N-7-methylated MXs (such as 7-methylxanthine, theobromine, and caffeine), where C-8 oxidation was the major pathway in the catabolism of 1-methylxanthine, whereas demethylation and C-8 oxidation are likely both involved in the degradation of theophylline. Enzymes responsible for MX degradation were located inside the cell. Both cell culture and cell-free enzyme assays revealed that N-1 demethylation might be a rate-limiting step for the catabolism of the MXs. Surprisingly, accumulation of uric acid was observed in a cell-free reaction system, which might be attributed to the lack of activity of uricase, a cytochrome c-coupled membrane integral enzyme.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2018년도 춘계학술발표회
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• pp.88-88
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• 2018

Coffee is one of the most popular drinks in the world. Roasting process of coffee bean is one of major steps to make coffee, however, there are few studies which analyzed chemical compounds in intermediate state of roasting coffee beans due to technical limitations to get coffee beans with the same roasting condition. We utilized Stronghold S7 pro roasting machine which guarantees the saming roasting conditions repletively with the aid of precise computer to control heat sources to get 20 steps (every 30 seconds) of roasted coffee beans during roasting process (10 min in total). Along with roasting process, phenolic compounds were decreased, which can be explained that roasting process cause phenolic compounds degradation. Caffeine is almost constant during roasting, reflecting that caffeine is not affected in roasting process. These samples presents that organic acids significantly increase along with the roasting process by HPLC analysis. With additional analysis of coffee beans, such as moisture contents, pH, as well as coffee tastes, our analysis will show detailed process of chemical compounds of coffee beans during roasting process.

• 한국식품저장유통학회지
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• 제12권1호
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• pp.1-7
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• 2005

저온$(5^{\circ}C)$에서 가루차를 일반포장, 일반포장+항산화제, 일반포장+방습제처리시 4개월 이후 품질관련 성분인 총질소, 총아미노산, 탄닌, 카페인, 엽록소, 지방산 함량이 상당히 저하되었으며, 일반포장 + 진공처리는 일반포장 저장에 비해 1개월 정도 저장기간의 연장이 가능하였다. 제품의 표면색상은 저온$(5^{\circ}C)$보관시 일반포장에서는 저장 1개월에 a값(녹색)이 -16.43에서 저장 5개월에는 $42\%$정도 감소된 -10.11로 크게 감소되었다. 외관과 내질에 따른 관능평가시 저온$(5^{\circ}C)$저장의 경우 일반포장 내에서 1개월 경과시 89점이었으나 3개월 보관시 78점으로 가루차의 외관과 내질이 크게 열악해졌으며, 일반포장 + 진공의 경우 4개월 보관시 79점으로 일반포장보다 1개월 정도 더 연장보관이 가능하였다. 본 연구에서는 진공포장한 가루차를 $5^{\circ}C$에서 저장한 것이 처리구 중 가장 우수한 결과를 나타내었다.

• Journal of Biosystems Engineering
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• 제41권4호
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• pp.365-372
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• 2016

Purpose: Tea is the most frequently consumed drink worldwide, next to water. About 75% of the total world tea production includes black tea, and withering is one of the major processing steps critical for the quality of black tea. There are two types of tea withering methods: physical and chemical withering. Withering can be achieved by using tat, tunnel, drum, and trough withering systems. Of these, the trough withering system is the most commonly used. This study focuses on the different types of withering, their effect on the various quality attributes of tea, and other aspects of withering methods that affect superior quality tea. Results: During physical withering, tea shoots loose moisture content that drops from approximately 70-80% to 60-70% (wet basis). This leads to increased sap concentration in tea leaf cells, and turgid leaves become flaccid. It also prevents tea shoots from damage during maceration or rolling. During chemical withering, complex chemical compounds break down into simpler ones volatile flavor compounds, amino acids, and simple sugars are formed. Withering increases enzymatic activities as well as the concentration of caffeine. Research indicates that about 15% of chlorophyll degradation occurs during withering. It is also reported that during withering lipids break down into simpler compounds and catechin levels decrease. Improper withering can cause adverse effects on subsequent manufacturing operations, such as maceration, rolling, fermentation, drying, and tea storage. Conclusion: Freshly harvested leaves are conditioned physically and chemically for subsequent processing. There is no specified withering duration, but 14-18 h is generally considered the optimum period. Proper and even withering of tea shoots greatly depends on the standards of plucking, handling, transportation, environmental conditions, time, and temperature. Thus, to ensure consumption of high quality tea, the withering step must be monitored carefully.