Enzymatic Valorisation of Hazelnut Skin and Hemp Shives By-Products

The valorisation of lignocellulosic agro-industrial residues through mild and sustainable processes represents a promising strategy for their conversion into value-added fractions. This study investigated an enzyme-assisted approach for the valorisation of hazelnut skins (HaSk) and hemp shives (HeSh), evaluating the effects of cellulase, hemicellulase, pectinase and xylanase treatments on sugar release, structural and morphological characteristics, functional properties of the residual solids, and phenolic content and antioxidant activity of the liquid fractions. Enzymatic treatments produced substrate- and enzyme-dependent effects. Hemicellulase showed the most pronounced general effects, particularly in terms of sugar release and modification of the solid matrices. Scanning electron microscopy confirmed changes in the surface morphology of treated materials. Enzymatic treatment also differently affected the functional properties of the two substrates, with HaSk showing enzyme-dependent changes in WHC, whereas HeSh maintained comparable or increased hydration properties and showed increased OHC following hemicellulase treatment. In the liquid fractions, enzymatic treatment increased total phenolic content and antioxidant activity, indicating enhanced release of phenolic compounds from the lignocellulosic matrices. Overall, the results support enzyme-assisted processing as a mild strategy for the valorisation of heterogeneous lignocellulosic residues, generating solid fractions with modified functional properties and liquid fractions enriched in phenolic compounds.