• Journal of Environmental Science International
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• v.27 no.12
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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.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.215-220
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• 1992

Several bacterial strains capable of degrading caffeine were isolated and studied for their biodegradation ability of the caffeine and some biochemical characteristics. The isolate KS-5 was identified as Pseudomonas putida and was designated as the P. putida KS-5. The optimum conditions were at $30^{\circ}C$, pH 7.0 and 1.0% caffeine. Agarose gel electrophoresis and curing experiment were found that the gene for caffeine degradation was encoded on the plasmid in P. putida KS-5 and that this strain was resistant to several antibiotics.

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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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.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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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.

• Food Science and Preservation
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• v.12 no.1
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• pp.1-7
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• 2005

The effect of packing methods on the green powder tea were investigated by examining quality changes during cold stroage. Packing was performed with aluminum packs having an antioxidant and a wateiproofing agent in vacuum Alumiunum packing with treatment or not showed little changes till 2 months but after this period remarkable quality degradation were found in total nitrogen, total amino acids, tannin, caffeine, chlorophyll and fatty acids. The color changes of gieeness were -16.43 in one month and -10.11 in five months, respectively. Alumininum packing in vacuum was showed extention of storage period above one month.

• Journal of Biosystems Engineering
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• v.41 no.4
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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.