Optimization of ultrasound-assisted enzymatic extraction of Sohiong (Prunus nepalensis) juice

Sohiong (Prunus nepalensis) fruit is an underutilized fruit of Northeastern part of India and is known as a rich source of micronutrients, polyphenols, and anthocyanin. The synergistic effect of ultrasound and enzymatic treatment on extraction of Sohiong fruit juice was investigated for maximum juice yield. The process variables in juice extraction were modeled and optimized by Box-Behnken design. The combined impact of ultrasound and pectinase enzyme on various quality characteristics was studied. The juice recovery and the quality of juice were found to be optimum at 90% ultrasound amplitude with ultrasound treatment time of 9.95 min, enzyme concentration of 0.03% w/w, and incubation time of 57.44 min. This process was then compared with only enzymatic extraction. As a whole ultrasound pretreatment significantly increases the juice yield by 20%, total soluble solids by 24%, anthocyanin by 25%, total phenols by 8%, and DPPH radical scavenging activity by 4.4%. Moreover, combined ultrasound and pectinase enzyme treatment significantly reduces the juice extraction time by 22 min compared with enzyme treatment alone. Hence, this could be an efficient alternative emerging technique to extract juice from the fruit.