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We used various kinds of wasted tea leaves to develop composite sheets with antibacterial properties. Antibacterial tests showed that the number of viable bacterial cells for the sheet containing wasted green tea leaves was around 10:-10 CFU/ml after 18 h culture compared to 108 CFU/ml for a tea-free sheet. This indicates that cell growth was signifi cantly inhibited. For sheets containing other types of tea leaves (oolong, black, hojicha, and pu-erh), living cells were not found, indicating that these sheets had superior antibacterial effects. Living cells were also not found in sheets containing wasted black tea leaves or roasted tea leaves at a concentration of 60% by weight after 6 h cultivation. Therefore, roasting treatment of wasted green tea leaves was examined to improve the antibacterial activity of the sheet. In particular, the focus was on structural conversion of catechins by heating. [ABSTRACT FROM AUTHOR]

The endurance of the antibacterial properties of compounded papers containing wasted green tea leaves needs to be examined before considering these papers for long-term use. Hence, compounded papers containing 60 wt% wasted green tea leaves were irradiated for 1–200 h using a xenon lamp to examine the effect of irradiation on antibacterial properties of the paper. Irradiation for 20 h (cumulative ultraviolet dose at 365 nm, 6.67 × 10 J/m) or longer was found to greatly increase the antibacterial activity of the paper to a level at which no bacterial cell was confirmed to be viable. The paper was also covered with various glass filters and irradiated for 1 h. Irradiation exclusively with visible rays did not significantly affect the antibacterial activity of the paper, whereas irradiation exclusively with ultraviolet rays, even for a short time, greatly increased the antibacterial activity. [ABSTRACT FROM AUTHOR]