Gamma-Aminobutyric acid (GABA), a hypotensive compound, is formed from glutamic acid under anaerobic condition in tea shoots. Glutamic acid was exhausted in the first three hours of anaerobic incubation and the increase of GABA stopped. After that, when tea shoots were released under aerobic condition, glutamic acid reproduced rapidly. After one hour of aerobic incubation, tea shoots were given three hours of anaerobic incubation again and then accumulated glutamic acid changed to GABA. The content of GABA increased much more than usual anaerobic incubation. GABA was more in the tea stem than in the leaf.

Frequency-dependent electrical impedance spectroscopy has been used to characterize the intracellular and extracellular resistances as well as the capacitance of the cell wall and cell membranes of tea leaves in the steaming process. The intracellular resistance of the steamed leaves decreased by approximately 90% as compared to that of fresh leaves. Water in the cytoplasm was transformed into mobile water by the steaming treatment. This is the main factor that causes the decrease in the intracellular resistance. However, when the treatment duration exceeded 20 s, there was a negligible influence on the change in the resistance. Therefore, this organized behavior was considered to occur within 20 s. On the other hand, since the indissoluble pectin that constitutes the cell wall became water soluble by the steaming treatment, positive ions accumulated on the cell wall at the beginning of the treatment. Therefore, the capacitance increased temporarily due to the treatment. In addition, when the steaming treatment was prolonged, the capacitance and extracellular resistance decreased due to deterioration and shrinkage of cellular tissues. Electrochemicalimpedance analysis can be employed to investigate the organized behaviors that occur in tea leaves in the steaming treatment. Therefore, a numerical method to evaluate the steaming . treatment can be established using electrochemical impedance analysis.

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SummarySerious frost damage to tea plants was observed in Shizuoka prefecture in March 2010. In this report, we present the results of a survey conducted on a tea field in which tea plants were injured by frost on March 30, 2010.A survey was conducted at a 0.1 ha tea field located in Makinohara, Shizuoka. Two frost protective fans (1.98 kW, 0.9 m diameter triple-blade) were mounted on 7-m-high steel towers installed at the tea field. The fan installed in the southern part of the field was operated continuously, whereas the fan installed in the northern part was virtually inactive because of energy saver control. Temperatures were monitored at 15 cm and 160 cm above the canopy of the tea plants and 7m above the ground. Wind speed and direction were measured at 1.9m above the canopy of the tea plants. Two weeks after the occurrence of frost injury, the canopy shoots were visually inspected in order to evaluate the damage.The observations and results of the survey can be summarized as follows: Between 2:00 am and 6:00 am on March 30, the nighttime air temperatures at both 15 cm above the canopy of the tea plants and 7 m above the ground dropped below freezing temperature.

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