Influence of cultivar on the lignocellulosic fractionation of grape stalks

This study was aimed to investigate the influence of grape cultivar on the lignocellulosic fractionation of grape-stalks. A four-step process (a washing treatment followed by an acid hydrolysis, a basic hydrolysis and, finally, a basic bleaching) was applied to stalks obtained from six different red and white grape cultivars. The different stalks were compared in terms of chemical composition of raw material (moisture, ash, minerals, lipids, fiber, proteins and free sugars) and of the recovered fractions (washing, acid and basic liquors and final cellulose residues). Recovery yields for free and hemicellulosic sugars, antioxidant compounds and cellulose were calculated. The cultivar significantly influenced all the investigated parameters, without characteristic performances between red and white cultivars. This result will need to be taken into account in the development of an optimized biorefinery approach for a large-scale exploitation of grape stalks.