Lipid occurrence, distribution and degradation to flavour volatiles during tea processing

The contents of neutral lipid, glycolipid and phospholipid and their fatty acid composition in three cultivars (clones) and processed leaves at different stages of black tea manufacture were measured. Glycolipids account for nearly 50% of the total lipids and are rich in linolenic acid. Phospholipids were present in the least amount (15%) and had a high proportion of oleic, linoleic and palmitic acids. Neutral lipids were found in moderate amounts (35%) and had a high content of lauric, myristic, palmitic, stearic, oleic and linoleic acids. Well-marked clonal variations in fatty acid composition of the lipid fractions were registered. With the maturation of the tea shoot, the lipid content increased. Considerable losses of lipids/fatty acids were observed in the withering process and again in the firing process. The other stages of processing (rolling and fermentation) registered only a minor change in lipid/fatty acid contents. Wide variation in lipid and flavour content was observed with season and a relation was evolved between them. The reason for the superior flavour of orthodox teas over CTC teas is explained on the basis of their lipid degradation. The changes in lipid content/fatty acids were related to the volatiles produced. (C) 1999 Elsevier Science Ltd. All rights reserved.