Ultrasonication Treatment Improves Butterfly Pea Flower’s (Clitoria ternatea L.) Anthocyanin Extraction as a Natural pH Indicator

Butterfly pea flower (Clitoria ternatea L.) is rich in anthocyanin, which can be utilized as a natural colorant. The color of anthocyanin changes based on pH values. Separating anthocyanin can be done by ultrasonication with ethanol solvents. This study aims to determine the effect of ultrasonication in butterfly pea flower extraction towards its yield, the value of pH extract, total anthocyanin, and color change sensitivity at different pH values. Butterfly pea extraction was performed with four different ultrasonication durations, i.e., 0 (without ultrasonication), 5, 10, and 15 minutes with five replications. The yield was evaluated using the gravimetry method. The value of pH extract was acquired using a pH meter. The total anthocyanin was determined by a differential pH method. Color change sensitivity was evaluated based on its red, green, and blue value (RGB). The study was conducted over 2 months. Analysis of variance (ANOVA) with a significance level of 5% and Duncan post-hoc analysis was used to evaluate the data. The results showed that the yield and total anthocyanin significantly increased as the ultrasonication duration increased and the color intensity became stronger. Whereas the value of pH extract slightly decreased with a longer ultrasonication duration. The best result was observed in 15 minutes of ultrasonication treatment with a yield of 71.03%, pH extract value of 6.69, and total anthocyanin of 16.99 mg/L. The extract also showed high color change sensitivity in different pH values, indicating its potential as a good pH indicator.