High voltage electrical discharges combined with enzymatic hydrolysis for extraction of polyphenols and fermentable sugars from orange peels

Abstract

Orange peels are a biomass rich in carbohydrates and polyphenols and characterized by their low lignin content. This work focuses on finding the best combination between physical and biological treatments to enhance the extraction of fermentable sugars and polyphenols. High voltage electrical discharges (HVED) (0 to 900 kJ/kg) or enzymatic hydrolysis with Viscozyme® L (12 FBGU/g) were applied on fresh or defatted orange peels for the extraction of polyphenols and fermentable sugars. An HVED energy input of 222 kJ/kg was optimal for the extraction of reducing sugars (19 g/100 g DM) and polyphenols (0.7 g/100 g DM). However, enzymatic hydrolysis allowed a higher extraction of reducing sugars (50 g/100 g DM). HVED were then applied prior or simultaneously to enzymatic hydrolysis to maximize the extraction of biomolecules from orange peels. Thus, the results clearly showed that the HVED pretreatment of orange peels is efficient to enhance the accessibility of cellulosic biomass to enzymes. HVED (222 kJ/kg) prior to enzymatic hydrolysis (12 FBGU/g), was the most effective combination of these two processes to get an intensive extraction of biomolecules from orange peels.

Keywords: Enzymatic hydrolysis; Extraction; Fermentable sugars; High voltage electrical discharges; Orange peels; Polyphenols.