Nitrogen fertilization of tea: Effect of tea leaf plucking criteria on chlorophyll and quality parameters

Abstract

The purpose of this investigation was to establish the possible effect of plucking criteria on the quality of black tea produced with different levels of nitrogen fertilization. Increases in leaf age (norms) resulted in increased total chlorophyll in fresh green tea leaves. Increases in levels of ammonium sulphate fertilization also increased chlorophyll. Chlorophyll responses were similar for processed black tea. Black tea had a much lower total chlorophyll content than fresh green leaves when expressed on the same fresh mass basis. The manufacturing process therefore caused some chlorophyll breakdown. An organoleptic evaluation showed that the infusion of the black tea was constantly ‘bright’ at all nitrogen (N) levels for bud + 1 and second leaf. The older leaves were mostly ‘dull’. These results follow the same pattern as those with increased chlorophyll content. The ‘grassy’ taste of the liquor was positively related to increases in chlorophyll content as well as to increases in leaf age (norm). Total chlorophyll content was higher in machine-plucked than in hand-plucked tea leaves.