Stability of anthocyanins from butterfly pea (Clitoria ternatea) flower extracted after storage at different conditions

Abstract

Flower from Butterfly pea (Clitoria ternatea) is known to contain the anthocyanins pigment in the petals. However, there was no widely research carried out to study the anthocyanins pigment in aqueous extracted from Butterfly pea flower. Therefore, this study was conducted to determine which extraction methods can produce the highest yield of anthocyanins pigment and to study the color properties through storage at different conditions (pH, temperature and light exposure). Three different solvent extraction methods were used to extract anthocyanins pigment which were ethanol acidified method, hydrochloric acid method and distilled water method. Meanwhile, for stability study the highest extracted anthocyanins pigment were stored at seven different conditions which were 4 °C and 27 °C (pH 1±0.5, dark), dark and bright conditions (pH 1±0.5, chill temperature) and pH 4, pH 7 and pH 10 (dark, chill temperature). The storage stability study of anthocyanins pigment was carried out (every week) within a month. The pH-differential method was used to determine the total anthocyanins pigment by taking the absorbance reading at 520nm for pH 1.0 and 700nm for pH 4.5. The color readings of lightness, 'a' and 'b' values measured using colorimeter and the 'a' and 'b' values were converted into chroma and hue. Findings showed that extraction using ethanol acidified method produced the highest yield of anthocyanins pigment. Therefore, this method was applied for the rest of the experimental works. Storage at different temperatures showed no differences of anthocyanins pigment and lightness with chroma value was unstable at both temperatures. However, hue was maintained towards storage as red in color. Storage at different light exposures also resulted no differences for anthocyanins pigment and lightness property showed stability in dark condition. Chroma values for both light condition was maintained but hue more predominat as red color in bright condition. Meanwhile, anthocyanins pigment showed stability as stored at pH 4 with hue in red color. While, chroma for all pH storage was maintained through storage periods. Overall, anthocyanins pigment was stable for storage in acidic condition with full dark condition.