Abstract:

Pigment in Brassica oleracea var. acephala D.C was extracted and purified to study the effects of temperature, sunlight, pH, acid agents and sugars on its stability and its antibacterial activities against E. coli, Staphyloccocus aureus and Bacillus subtilis. The pigment had some light resistance and its red color could be maintained when exposed to sunlight, which had little change after 2 h heating at temperatures bellow 60 ℃, but became light and even disappeared when heating temperature was above 60 ℃. pH displayed a great effect on the pigment, which showed a stable red color below pH 2. Acid agents and sugars both had hyperchromic and protective effects on the pigment, and in terms of effectiveness and lasting time, the former was superior to the latter. Of three acid agents tested, lactic acid exhibited the best hyperchromic effect. The hyperchromic effect of glucose was better than that of other two sugars tested. The hyperchromic and protective effects of sugars, however, would progressively decline and even disappear with the storage time prolonging. The pigment had distinct antibacterial activities against E. coli, and Staphyloccocus aureus, especially against Bacillus subtilis. The results above benefit the development and utilization of the pigment as helpful references.

Key words: Brassica oleracea var. acephala, pigment, stability, antibacterial antivity