Analysis of Selected Biochemical Constituents in Black Tea (Camellia sinensis) for Predicting the Quality of Tea Germplasm in Sri Lanka

Twenty two accessions from tea (Camellia sinensis) germplasm representing high, moderate and low quality of made tea were used for black tea production in wet and dry seasons. Total polyphenol content, total free amino acid content, total liquor colour and brightness were analysed by spectrophotometric methods and correlated with organoleptic parameters viz infused leaf colour, colour of liquor, strength and quality. Strong positive correlations were identified between infused leaf colour and total liquor colour with total quality score. It was also found that the polyphenol content had a positive correlation with brightness which was responsible for liquor quality. The resultant dendrogram of cluster analysis enabled separation of these accessions into high, moderate and low quality categories. Principal Component analysis (PCA) revealed that, of the 16 parameters studied, infused leaf colour has the highest contribution towards clustering of accessions. Group III represented 5 well established high quality accessions (DT1, DUN7, NAY3, TRI 777 and PK2) and group I represented moderate quality accessions including two accessions (N2 and TRI 4079) which were previously categorized in the high quality group. Therefore, polyphenol content, total liquor colour, brightness and infused leaf colour could be used as reliable quality parameters, whereas total amino acid and crude fibre contents cannot be considered as useful quality parameters. Furthermore, fermentation rate was determined for the 22 accessions and four groups were identified based on the fermentation rate. Results revealed that the fermentation rate could be used as an early selection criterion for determination of fermentation properties of tea accessions at progeny level.

Tropical Agricultural Research Vol. 23 (1): 30-41 (2011)