Functional Properties Optimization of Carboxymethylcellulose-Based Films Enriched with Bioactive Compounds from Olive Leaf Co-products

Composite carboxymethyl cellulose (CMC)-based films containing olive leaf extract (OLE) and the polysaccharide fraction from olive leaves (PFOL) were produced by a solvent casting method. The effects of OLE and PFOL contents on physical and functional properties of CMC composite films were assessed using a two-factor, five-level central composite design. Overall, water barrier properties of CMC-based films were significantly improved upon OLE and PFOL incorporation as confirmed by the observed reduction in their water absorption and water vapor permeability (WVP). Likewise, increasing PFOL content from 0 to 60 wt% significantly enhanced the flexibility of CMC/PFOL composite films, most likely due the increased mobility of CMC chains due to the formation of new hydrogen bonds between the CMC chains and the phenolic compounds in PFOL. Furthermore, the incorporation of OLE and PFOL endowed the CMC composite films with higher antioxidant capacity and excellent light barrier properties. Using the desirability function approach, an OLE contents of 0.51 wt% and 59.85 wt% PFOL were identified as the optimum factor levels providing maximum %E (23.28%), higher antioxidant activity (1.1 µmol TE/mg extract), and minimum WVP (17.62 g mm m⁻² j⁻¹ kPa⁻¹), with an overall desirability of 0.984.

Graphical Abstract