Effect of pH and added sugar on stability of color, anthocyanin content and phenolic content of Clitoria ternatea, Ipomoea tricolor and Brassica oleracea extracts

บทคัดย่อ

The effect was determined of different types of sugar (sucrose, glucose, maltose) at different concentrations (10%, 20%, 30%) on the stability of three sources of anthocyanin extract (Clitoria ternatea flowers, Ipomoea tricolor flowers, Brassica oleracea leaves) during storage at pH 5 and pH 6. The anthocyanin of plant samples was extracted using deionized water for 30 min at 60oC with continuous shaking. The stability parameters in the study were color intensity, total anthocyanin content and total phenolic content. The highest stability was recorded for C. ternatea, followed by I. tricolor and B. oleracea, respectively. The half-life vales of color intensity of C. ternatea at pH 5 and pH 6 with various sugar concentrations added were in the range 77.88–231.05 d, while the half-life values of Ipomoea tricolor and Brassica oleracea were 37.27–87.74 d and 23.03–48.81 d, respectively. Increasing the amount of added sugar increased the stability of all the extracts. Compared to the extracts without sugar, the addition of 30% sugar increased the half-lives of color intensity, total anthocyanin content and total phenolic content for all extracts by 1.54–2.01 times, 1.90–2.26 times and 1.76–2.11 times, respectively. However, the type of sugar had no significant effect on any of the stability parameters of the extracts.