Antibacterial activity of compounded papers using wasted green tealeaves produced by paper-making method

Various studies were conducted to improve antibacterial properties of compounded papers using wasted green tealeaves prepared by a paper-making technique. The research included the elucidation of a cause of low antibacterial activity. Different binders and different degrees of grinding wasted tealeaves were tested with no effect on antibacterial properties of compounded papers using wasted green tealeaves. However, when a suspension of pulp and wasted tealeaves was air-dried and used to prepare a compounded paper, the compounded paper was found to have excellent antibacterial properties. The result indicated a cause for the low antibacterial activity of compounded papers using wasted green tealeaves prepared by the paper-making technique. That is, catechins abundant in wasted green tealeaves dissolved in water when ground and ran off with waste water during the paper-making process without settling in compounded papers. To confirm that, liquid from a mass-colloider used for wet-grinding wasted tealeaves was sampled and filtered. The filtrate was dropped onto a 100 wt% pulp paper. No viable bacterial cell was found in the pulp paper to which more than 1.0 ml/g of the filtrate was applied; the result showed that the liquid possessed good antibacterial properties. In other words, the liquid was confirmed to possess a high antibacterial activity. In paper making by the paper-making technique, aluminum sulfate was added to a suspension of pulp and ground, wasted tealeaves in order to readily settle catechins contained in liquid resulting from grinding wasted tealeaves in compounded papers using wasted tealeaves. The result revealed that a 2.70 wt% addition of aluminum sulfate to compounded papers using wasted green tealeaves improved antibacterial properties of the papers.