The impact of processing techniques on tea volatiles

Abstract

The impact of various cultural and manufacturing techniques on volatile flavour composition was studied in order to optimize the conditions for production and retention of aroma in relation to tea quality. The Flavour Index was in the order: clonal variation—Assam > > Cambod > China Shoot maturity—Bud + 1st leaf > > > 2nd leaf > > 3rd leaf; plucking interval 7 day > 14 day; processing—green leaf > withered leaf—fermented dhool < dried tea < < tea brew; withering—soft < normal < hard. VFC Group I was in general dominated by trans-2-hexenal and Group II by linalool, phenylacetaldehyde and geraniol. Fresh green leaf had a high content of hexanol, hexanal, hexenol, hexenal and methyl salicylate. Upon withering, a sharp increase in Group I was noticed, the most remarkable being in hexenol. Group II also increased, but the extent was less except for linalool. During fermentation, Group I alcohols showed a sharp reduction with concomitant increases in aldehydes, especially trans-2-hexenal. In Group II, all compounds increased except methyl salicylate and the ionones. In the firing stage, high losses of Group I and Group II were registered. All the Group I compounds showed a decline with the progress of withering, but the opposite applied to Group II compounds, except for the alcohols. Mechanical injury during handling of leaf before cutting increased the Group I content enormously. The addition of exogenous fatty acids, mainly linoleic acid, produced substantial amounts of Group I compounds, dominated by trans-2-hexenal and hexanal. The inhibition of lipoxygenase totally reduced the formation of Group I volatiles.