Abstract:
Sri Lankan teas are accepted as the finest tea produced in the world. Quality of tea is determined by
it‟s physical, chemical and microbiological properties. But very few research studies shown the
variation of quality parameters during black tea manufacturing against the manufacturing method and
selling catalogues. Therefore, this case study was conducted to investigate the variation of selected
quality parameters of Orthodox black tea from Uva high region during its manufacturing process. In
Chemical analysis, Total polyphenol content (TPC) (ISO 14502-1;2005) and radical scavenging
activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) (AOAC International standards) were determined
with some modifications to the standard analytical methods. Samples were taken (n=3) from six
stages of manufacturing process. The IC50 values of DPPH radical scavenging activity changed from
7.96±0.08 ppm (withering) to 69.79±3.73 ppm (winnowing), indicating that withering stage has
highest antioxidant content. The TPC ranged from 1.46 ±0.03 to 6.08 ±0.11 mg GAE g-1 dry leaves
but no linear relationship exists between TPC and antioxidant activity (p>0.05) (R2 = 0.4803). In
microbial analysis, Total plate and Yeast and mold counts were determined (Sri Lanka Tea Board -
SLS 516: part 1 and SLS 516:2;1991) and highest microbial counts were identified in winnowing
stage as 6.22x106 CFU g-1 (Total plate count) and 2.82 x106 CFU g-1 (yeast and mold count)
respectively. However, the tea collected from packing, had not exceeded the acceptable levels of
minimum requirement for exportation (ISO 3720:2011). Research findings exhibit that the tea
manufactured in respective factory, is satisfied the minimum requirements for exportation but hand
hygiene practices, and cleanliness of contacting surfaces may be the cause of highest microbial
counts of tea samples in winnowing. This study recommends further studying of microbial
parameters to investigate the contaminations of tea in tea factories.
Keywords: Orthodox black tea; Uva high region; Selling Catalogue; Antioxidant activity
