Grape stalk: a first attempt to disentangle its fibres via electrostatic separation

The aim of the study was to assess the effectiveness of the electrostatic separation on fractionation and deconstruction of the grape stalks lignocellulosic biomass. After the measurements of their physical properties, the eight fractions obtained were extracted with hot water and then with hot 2% sulphuric acid. In aqueous extracts, the concentrations of glucose and fructose of samples collected in the jars under the positive electrode were as high as 13.5 and 11.6 g/100 g d.w., respectively. As for acid hydrolysis, the concentration of furfural and HMF were 1996–2600 and 144–291 mg/kg d.w., respectively. The results showed the opportunity of using grape stalks as a source of fermentable sugars, as well as a potential source of furanic compounds. This technique can represent a new and affordable method of lignocellulosic biomass pre-treatment which can easily be integrated into a biorefinery to favour partial fractionation and better exposure of the fractions to a subsequent enzymatic or chemical attack.