Pre-treatment to enhance the energetic yield of winemaking by-products

On the basis, agro-food wastes can represent a potential energy resource even if the biological transformation to methane is mainly limited to hydrolytic pre-treatment for producing simple sugar to be rapidly fermented. Grape stalks for example have a high percentage of lignin and cellulose and can’t be used, whitout pretreatment, for an anaerobic digestion process. Our findings show enzymatic and thermo-mechanical pre-treatments in combined application for optimise hydrolytic mechanism on winemaking wastes which represents 0,9 milion ton/year in Italy. A screening of specifically industrial enzymatic complex for the hydrolysis lignocellulosic biomass were tested using the principal polysaccharides component of the vegetal cells. Hydrolysis test are optimized for the different feedstock, in particular grapes stalk and marc from winery industry. A combination of thermo-mechanical treatment at different temperatures as well enzymatic concentrations from 0,1% to 5% w/w showed an increasing release of simple sugars up to 25% depending to the kind of feedstock. The optimisation of the operative factors permits to justify an industrial useful of this application in which the sugar concentration has yielded a maximum of 21 gr/L and 30 gr/L with grapes stalk and marc, respectively.