Optimization of Antimicrobial Functionalization of Bacterial Cellulose Using Winery By-Products and Carboxymethyl Cellulose as Linker

The growing need for sustainable strategies to reduce agro-industrial waste has stimulated interest in valorizing winery by-products as sources of high-value bioactive compounds. Wine lees, rich in phenolic compounds with well-documented antimicrobial activity, remain largely underutilized in the development of functional materials. In most cases, incorporation of bioactive agents relies on physical adsorption, which often results in weak adhesion and limited durability. In this study, phenolic extracts derived from wine lees and grape seed extract were incorporated into bacterial cellulose (BC) to develop bioactive materials with antimicrobial and antioxidant functionality. Two strategies were investigated: (i) direct immersion of BC in phenolic extracts and (ii) incorporation of extracts in BC membranes pre-modified with carboxymethyl cellulose (CMC) to enhance phenolic affinity and retention. The resulting materials were characterized for total phenolic content, antioxidant activity, and antimicrobial performance against bacterial strains ( Escherichia coli , Salmonella Typhimurium, and Staphylococcus aureus ). CMC-pretreated membranes significantly enhanced phenolic incorporation and antimicrobial performance, achieving a 99.9% reduction in E. coli after 24 h, while S. Typhimurium and S. aureus counts were below the detection limit (LOD < 1.0 log 10 CFU/mL). These findings demonstrate the potential of wine lees as a sustainable source of bioactive compounds for the development of antimicrobial cellulose-based materials, supporting circular bioeconomy strategies and their potential application in food packaging.