Polyphenols, reducing sugars and soluble lignin extraction from vine shoots by High Voltage Electrical Discharges, enzymatic and alkaline hydrolyses

Abstract

In this study, the efficiency of enzymatic (Viscozyme® L) and alkaline (1 M NaOH) hydrolyses in terms of polyphenol, reducing sugars’ and lignin extraction from Vitis vinifera vine shoots var. Grenache Blanc was showed. The combination of High Voltage Electrical Discharges (HVED) with enzymatic hydrolysis was also conducted prior to alkaline hydrolysis. Enzymatic hydrolysis (24 FBGU/g) extracted 2 mg/g of polyphenols, 80 mg/g of reducing sugars and 0.7 % of soluble lignin, whereas alkaline hydrolysis (1 M NaOH) extracted 10 mg/g of polyphenols, 5 mg/g of reducing sugars and 8 % of soluble lignin. The application of HVED (101.6 kJ/kg) prior to enzymatic hydrolysis ameliorated by 1.8; 1.4 and 2.14 times the extraction of polyphenols, reducing sugars and soluble lignin, respectively. The combination of physical and biochemical methods led to the highest resveratrol, p-coumaric and ferulic acids’ yields as shown by HPLC.