Optimization of ultrasound assisted extraction of anthocyanin from grape skin through response surface methodology

Anthocyanins are the compounds responsible for imparting dark colour to fruits and vegetables. The extraction of anthocyanin from Grapes (Vitis vinifera) skin by ultrasonic-assisted process was studied. Optimization of operating conditions, such as the ratio of amplitude, extraction temperature and extraction time, on the extraction yield of anthocyanins was carried out through response surface methodology (RSM). The developed experimental design with a factorial 3³, where the factors were amplitude, temperature, time at the levels 20%, 40%, 60%, at times 5 min, 10 min, 25 min, and at temperatures 20°C, 30°C, and 50°C for each factor respectively. Using response surface methodology, the optimal set of extraction variables were obtained for maximizing the concentration of anthocyanins from the grape peel extracts. Ultrasonic- assisted extraction is found to be more efficient and rapid for extraction. Having higher amplitude at 60% achieved maximum extraction levels (300.4 – 304.5 mg). Reduction in extraction volume was comparable at such amplitude and extraction time for temperatures 20 to 40 °C. Allowing 60 min extraction time at 60% amplitude achieved maximum extraction levels at 50 °C which is comparable to theresultspredicted by the statistical tool as 60%, 44°C for 20 min.