乙醇模式溶液中李子花青素穩定度之研究

Abstract

Anthocyanin is water-soluble pigment displaying colors from red to blue and is widespread in plants. Factors such as pH, temperature, light, storage time, and the presence of complex compounds (flavonoids, phenolic acids and metal ions) influence the structure of anthocyanin, then the displaying of color. Plum contains large amount of anthocyanins, mainly cyanidin-3-glucoside (cyn-3-glc) and cyanidin-3-rutinoside (cyn-3-rut), and the quality of plum wine depends largely on these anthocyanins. The objective of the present experiment is to study the color stability of the purified cyn-3-glc and cyn-3-rut singly and in combinations in the ethanolic model solutions to find out the effect of ethanol on the color of the plum anthocyanin model solutions. Cyn-3-glc and cyn-3-rut were isolated and purified from plums, and the model solutions containing 6 %, 12 % and 20 % ethanol were simulated to the conditions of cooler drinks, fruit wines and port wines at pH 3.5. By this, we performed experiments to understand how the color stability of the two major anthocyanins is in plum liqueur during storage at 37 ºC. For the model solutions, results show that cyn-3-glc and cyn-3 rut degrade at different rates when they co-exist in the same solution. Although the combined anthocyanin model solution shows higher color intensity, the pure anthocyanin solutions show better color retention and slower degradation rates. The combined anthocyanin model solution shows similar results in anthocyanin retention compared to the liqueur samples. The cyn-3-glc is less affected by ethanol concentration but the degradation of cyn-3-rut increases with increment of the ethanol concentration. For the two purified singular anthocyanin models, the tested ethanol concentrations make no difference in anthocyanin degradation but the presence of ethanol slows down the degradation rate.