Stability of Betalain Pigments from Red Beetroot (Beta vulgaris)

摘要

The crude pigments obtained from red beetroot (Beta vulgaris L.) as root juice, were evaluated for their stability at various pH values, different ascorbic acid concentrations, and in the presence of N_2 and air. The effect of pasteurisation and storage periods with exposure to light and dark at room temperature and in refrigerator in both the presence and the absence of ascorbic acid as stabilizer was also estimated. The stability of extracted pigments was measured on the basis of their UV-visible absorption spectrum.The stability was found to be strongly dependent on pH values, hence it was the best at pH values between 6.5 and 7. Ascorbic acid at 0.05% was the best concentration to protect the red colour. Both samples treated with ascorbic acid or pasteurisation had much better stability in refrigerator than at room temperature in light or dark after 35 days. The exclusion of light and the presence of N_2 improved the stability of beetroot pigments. Beetroot pigments exhibited good stability under selected conditions and these characteristics give them considerable importance to be used in the pharmaceutical and food industries.