Optimization of ultrasound-assisted extraction of bioactive compounds from blueberry (Vaccinium corymbosum) peel var. Emerald and var. Ventura

Abstract

This work aimed to optimize the ultrasound-assisted extraction conditions (time and ethanol concentration) of bioactive compounds from discarded blueberry peel of the Emerald and Ventura varieties. For this, the Rotational Central Composite Design (RCCD) and the Response Surface Methodology (RSM) were used to maximize the total phenolic compounds (CFT) and antioxidant capacity (AC), individually and combined (CFT/CA). It was observed that the Emerald variety tends to contain higher levels of CFT, while the Ventura variety tends to have higher levels of CA. From the response surfaces, it was determined that high levels of CFT and CA are obtained in the blueberry peel of both varieties when the sonication time is in the range of 20 to 40 min and the ethanol concentration is between 40-70 %. Finally, the conditions that allowed maximizing the levels of CFT, CA, CFT/CA were determined for the Ventura variety: CTT (59.5% ethanol, 34.6 min), CA (45% ethanol, 40 min) and CFT/CA (58% ethanol, 36.5 min); and for the Emerald variety: CFT (50% ethanol, 29.1 min); CA (50.8% ethanol, 28.8 min) and CFT/CA (50.8% ethanol, 28.8 min). Under the UAE optimized conditions, values of CFT (3.05x104 μg GAE /g dry matter) and CA (9.14x104 μg of Trolox/g of dry matter) corresponded to the variety Ventura, while values of CFT (3.67x104 μg GAE /g dry matter) and CA (7.24x104 μg of Trolox/g of dry matter) corresponded to the variety Emerald.