• Journal of the Korean Magnetic Resonance Society
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• v.21 no.4
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• pp.119-125
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• 2017

The plucking season of green tea leaves is one of the important parameters that decide their metabolic diversity, quality, and prices. The effects of plucking sghlwleasons on green tea metabolites were investigated through metabolite profiling by $^1H$ NMR spectroscopy. The orthogonal projection on latent structure-discriminant analysis (OPLS-DA) showed clear discriminations of green teas by three different grades depending on plucking seasons: Ujeon, Sejak, and Jungjak. These results suggested that the nine peak groups could be used for diagnostics for identification of high quality Ujeon grade of green tea.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2001.11b
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• pp.74-78
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• 2001

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.4
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• pp.132-138
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• 2018

The plucking season of green tea leaves is one of the important parameters that decide their metabolic quality. Here, we performed the identification and quantity analysis of the metabolites of the green tea using NMR spectroscopy. We assigned the $^1H$ resonances for sixteen metabolites. This analysis found that four metabolites, gallic acid, quinic acid, theobromine and ECG, exhibited clear discrimination of green teas by the three different grades, Ujeon, Sejak and Jungjak. Our results suggest that these four metabolites could be used for diagnostics for quality control of green tea.

• Korean Journal of Food Science and Technology
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• v.39 no.3
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• pp.246-254
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• 2007

Fresh tea leaves grown in Jeju Island and Jeonnam Province of South Korea were plucked and processed. Volatile compounds (VCs) were analyzed and identified with SPME-GC/GC-MS/GC-O. The VCs of green teas were classified into two major categories based on their aroma characteristics: the Greenish (Group I), and Floral (Group II) odorants. It was found that the VCs were decreased significantly in fresh tea leaves as they were plucked at the later stages of cultivation. The ratio of VCs responsible for Group I and Group II compounds was well-balanced in tea leaves plucked in May, but the balances were changed when the fresh leaves were processed. The major VCs of fresh tea leaves in Jeju and Jeonnam were n-hexanal, E-2-hexenal, Z-3-hexenal, myrcene, benzyl alcohol, linalool, and phenyl alcohol. Also, Jeju and Jeonnam tea leaves had different aroma composition. n-Heptanol, ${\beta}-pinene$, benzaldehyde, and ethyl salicylate were found in Jeju fresh tea leaves, and Z-3-hexenol, E-2-hexenol, and methyl n-heptanoate were detected in Jeju dry tea leaves. On the other hand, Z-linalool oxide and myrcene were found in Jeonnam dry tea leaves. The SPME-GC method showed high reproducibility (RSD, 7.4%) with no-artifact formation. In this study, optimum plucking period of tea leaves could be determined for production of high quality green tea with a well-balanced aroma and characteristic VCs in green tea according to growing areas.

• Applied Biological Chemistry
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• v.46 no.1
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• pp.23-27
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• 2003

Lipoxygenase is the enzyme responsible for the formation of $C_6$-alcohols and $C_6$-aldehydes ($C_6$-compounds), which are well blown contributors to various types of 'green odor' In green tea. Changes in lipoxygenase activity and volatile compounds of green tea leaves were monitored daily during early growing season. The enzyme activity was spectrophotometrically measured using linoleic acid as a substrate. The volatile compounds were extracted through Solid Phase Micro-Extraction, and were subjected to GC and GC-MS analyses. Results showed that lipoxygenase activity and levels of $C_6$-compounds concomitantly increased or decreased during the early growing season, probably caused by the fluctuation in the daily temperature; increase in temperature led to the increase in enzyme activities and $C_6$-compound levels, whereas leaves plucked too early had low volatile compound levels. In this study, optimum plucking time of tea leaves for the production of high quality green tea with a wellbalanced aroma was determined.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.2
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• pp.163-169
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• 1995

This study was conducted 1) to compare the nutrient content and mineral composition of the Philoppine indigenous sheep and goats diets when grazed in common pasture during rainy season, 2) to determine the influence of sampling methods on nutrient content and mineral composition of upland (UP) and lowland (LP) native pastures, and 3) to compare these two pasture types in terms of nutrient and mineral composition. Experiment 1 used sis esophageally fistulated animals, three each for sheep and goats. Weekly extrusa collection was done for a period of three months. Experiment 2 was conducted in UP and LP; these were sampled thrice by three methods, plucking, clipping and use of three esophageally fistulated sheep. Results of Experiment 1 indicated that the diets of sheep were greater in crude protein(CP; p < 0.01) and ether extract(EE; p < 0.05) but lower in crude fiber (CF) and acid detergent lignin (ADL; p < 0.05) than that of goat diets. All other nutrient fractions including mineral composition were not significantly different from each other. Significant findings of Experiment 2 were: CP content of UP was in the order fistulated > plucked > clipped (p < 0.05); CP content of LP was greater (p <0 .05) in fistulated and plucked samples; and ash content was greater (p < 0.05) in fistulated samples of both pastures. The CP of UP was different (p < 0.05) from each sampling method but the CP of LP and ADL of both pastures were greater (p < 0.05) in clipped samples. Most minerals either macro or microminerals were greater in fistulated samples of both pastures. Pooled data of the two pastures showed that LP had better nutrient characteristics and greater mineral composition. Based from this study, there were few differences between the diets of indigenous sheep and goats when grazed in common pasture. Also, sampling methods influenced the nutrient composition of indigenous sheep diets.