Ultrasonic-assisted betalain extraction from red dragon fruit pulp (Hylocereus polyrhizus) using response surface...

Ultrasonic-assisted extraction (UAE) was employed for the maximum recovery of betalain pigment from red dragon fruit pulp using response surface variables as temperature (25-65 °C), extraction time (5-25 min), number of extractions (1-5), and solid/mass ratio (1:5-1:15 v/v). UAE at 25 kHz increased the betacyanin yield by 32 % i.e. 15.18-20.03 mg/100 ml and betaxanthin by 30 % i.e. 6.39-8.31 mg/100 ml in fresh dragon fruit pulp respectively. The central composite rotatable design was found to be best fitted with data having a higher R² (91 and 97 %), lower value of standard error and scattered plot. Maximum recovery of betalain pigment from pulp was obtained at 55 °C, 20 min, four extractions and 1:12.5 v/v because at higher temperature breakdown of compact tissues of fruit lead to the release of pigments and further increase in temperature (55 °C) can cause degradation of pigment. This study provides sustainable data for process design and industrial scale-up operations.