Stability of the crude extracts of Ranunculus asiaticus anthocyanins and their use as food colourants

Crude extracts of Ranunculus asiaticus anthocyanin pigment were obtained using several solvents, and their stability to light and heat with varying pH and water activity (aw) levels was studied. Yield of the crude pigments was approximately 48 mg g(-1) petals as cyanidin-3-glucoside equivalents in HCl: methanol (1:99, v:v). The pigment was moderately stable to heating at 50 degrees C and 80 degrees C, with its degradation curve showing two linear stages with heating time. The heat stability of the pigment extract in a buffer system was reduced by increasing the pH and water activity of the heating medium, and by inclusion of sugar. Light had a highly significant (P <= 0.01) negative effect on the pigment stability during storage especially in the presence of sugar. The pigment used in the colouring of a carbonated beverage was more stable during long time storage at 4 degrees C than at room temperature. The ethanolic pigment extract could be used successfully in the colouring of gelatine desserts and carbonated beverages, as well as yogurt.