Temporal depletion of packaged tea antioxidant quality under commercial storage condition

Shelf life studies play a significant role in determination of time duration for the retention of product quality after packaging. Assessment of tea shelf life in terms of antioxidant quality, a prime health benefit trait of tea would substantiate its marketing and consumption preference to the trade and end users. In shelf life analysis of tea with respect to its antioxidant potentialities, both antioxidant activity and incidences of secondary metabolites are responsible. A temporal analysis with regular intervals since 1 year of said characteristics has been carried out in four types of processed teas. To be precise, the overall initial antioxidant concentrations and activities were almost maintained up to 90-120 days and thereafter declination appeared. Beyond 180 days, rapid declination occurs and beyond 330 days, depletion recorded up to 60-75% of the initial activity. Black tea showed maximum ferrous ion chelating activity initially and white tea commenced with slight lower value but it maintained a similar trend up to 150 days while a rapid declination occurred in such activity of black and green tea after 30 days only. It is observed that total tannins or proanthocyanidins amount highest in white tea among all other three types. The preservation of metal chelating activity of white tea was observed as comparable to its stability in tannin composition (r² = 0.869, P ≤ 0.01) during the storage period.