Influence of processing stages on antimutagenic and antioxidant potentialsof rooibos tea

The antimutagenic and;antioxidant potentials of rooibos (Aspalathus lineari s) tea samples, collected from each of its major processing stages, were ev aluated according to the Salmonella typhimurium mutagenicity test and the h ydrogen donating ability and superoxide anion radical scavenging assays, re spectively. Ten random samples were collected before and after fel mentatio n, as well as after sun-drying, sieving, and steam pasteurization. Results indicated that the fermented tea had a significantly (P < 0.05) lower antim utagenic and antioxidant potential than the unfermented tea. Of the differe nt processing stages, the most significant reduction in the antimutagenic: and antioxidant property of the tea was found during the "fermentation" ste p. Sun-drying, sieving, and steam pasteurization also reduced the antimutag enic potential of the tea, although not to the same extent as the first pro cessing step. The hydrogen donating ability was significantly increased aft er steam pasteurization in comparison to those of fermented and sun-dried t ea. Pasteurization did not affect superoxide anion radical scavenging in co mparison to fermented tea. Differences seem to exist in the antimutagenicit y and antioxidant potencies of the tea sampled at the various stages during processing. A possible role of tea polyphenols in the antimutagenic and an tioxdant activities of the tea is suggested as processing caused a signific ant reduction in the total polyphenolic content.