Some studies on carotenoids and their degradation in black tea manufacture

Abstract

Abstract The four major carotenoids, β‐carotene, lutein, violaxanthine and neoxanthine were estimated spectroscopically in four different Tocklai Experimental Station released tea clones, namely, TV‐1 (China hybrid), TV‐2 (Assam(Betjan) variety), TV‐9 (Assam‐Cambod variety) and TV‐17 (China hybrid). The quantitative changes of these carotenoids in different stages of black‐tea manufacture were also studied in TV‐2 (less flavoury) and TV‐17 (flavoury) clones against TV‐1 as standard. Comparative study showed that TV‐2 contained the least amount of these carotenoids where as TV‐9 and TV‐17 contained greater amounts. All these carotenoids were found to decrease appreciably during black‐tea manufacture. The decrease was found to be higher in the curling, tearing, crushing method than in the conventional orthodox method of tea manufacture. The changes of two of these carotenoids viz . β‐carotene and lutein were not significant statistically during withering but were highly significant during fermentation. However, the reverse was true for violaxanthine where as the neoxanthine shows significant changes in both of these stages. The vitamin‐A value was calculated from the residual β‐carotene amount, pro‐vitamin A, in black tea.