Effect of blister blight disease on the biochemical and quality constituents of green leaf and CTC tea.
The effect of blister blight disease caused by Exobasidium vexans on some biochemical and quality parameters of black tea grown in Tamil Nadu, India was studied in 1996. The disease caused a reduction in the contents of polyphenols, catechins and enzymes present in green leaf which are known to be important precursors determining the quality of black tea. A corresponding decrease in the quality constituents like theaflavine and quality parameters such as total liquid colour and water-soluble solids were also observed in brewed tea. The disease caused an increase in palmitic acid content and a decrease in unsaturated long-chain fatty acids. The flavour index value showed a decline upon infection. The analytical data obtained were further confirmed with tasters' evaluation. The disease caused difficulty in withering and fermentation during tea processing.