Electrical, mechanical, and chemical effects of high-voltage electrical discharges on the polyphenol extraction from vine shoots

Abstract

Abstract The aim of this work was to study the mechanical, electrical and chemical effects of high-voltage electrical discharges (HVED) and their role in polyphenol extraction from vine shoots. Cutting and grinding pretreatments were conducted prior to HVED treatment. Thus, different initial specific surface areas ( a 0 = 6, 8.5, 11, 84 and 1885.19 cm − 1 ) of vine shoots were tested. When the initial specific surface areas were low ( a 0 = 6, 8.5, 11 cm − 1 ), the HVED induced damage degrees ( D ) were the highest, leading to a better enhancement of polyphenol extraction. However, no product fragmentation was found for the lowest particle size ( a 0 = 1885.19 cm − 1 ) before and after the HVED treatment, and despite it, an amelioration of polyphenol content in extract of 20 mg/L was observed. The electrical arc generated H 2 O 2 but did not lead to polyphenol degradation. Industrial relevance This study gives significant information about the action mechanisms of high voltage electrical discharge treatment presenting relevant data for the design of the process. It shows the effectiveness of electrical discharges for the intensification of the extraction of bioactive molecules (polyphenols) from a specific byproduct (vine shoots). The paper also presents an energy-saving extraction process, relevant for industrial application, since no organic solvents were used. Process duration and temperature were also reduced.