COLOR AND STABILITY OF PURE ANTHOCYANINS INFLUENCED BY PH INCLUDING THE ALKALINE REGION

This study on anthocyanin colour variation (intensity, lambda(max), ep silon) over the pH range 1-9 during 60 days of storage, was conducted on petunidin beta-D-glucopyranoside]-5-O-beta-D-glucopyranoside (petan in) and cyanidin 3-O-beta-D-glucopyranoside (cy3glc) at 10 and 23 degr ees C. Compared to cy3glc, petanin afforded higher colour intensity an d higher or similar stability throughout the whole pH range. At pH 4.0 , 84% of petanin was intact after 60 days storage at 10 degrees C, whi le the corresponding solution of cy3glc was totally degraded. At pH 8. 1 the colour intensity of petanin was even higher than at the lowest p H values. The visible lambda(max) absorption of petanin after 5 days a t pH 8.1 at 10 degrees C was similar or higher than the corresponding absorptions of the fresh solutions of cy3glc at any pH. The use of ant hocyanins like petanin as food colorants in slightly alkaline products (bakery, milk, egg, etc.) should therefore be considered-at least in products with limited storage time kept in a refrigerator. (C) 1998 El sevier Science Ltd. All rights reserved.