Effect of Ethanol Extract of Propolis on Paper Packaging Material

Propolis is a natural, accessible, and valuable bee product belonging to the group of so-called bioproducts. Its composition varies significantly depending on a number of factors, resulting in a wide range of data. The aim of this work is to investigate the antimicrobial effect of propolis extract, prepared with 70% ethanol, on packaging paper. Three propolis samples from Bulgaria were used: from the Northeastern region—harvest 1993 and 2023—and from the Central region—harvest 2023. Paper samples from a cellulose blend only and a base paper with improved hydrophobicity from cellulose blends of two samples of bleached kraft woodfree pulp are used for the analysis. The antimicrobial activity of ethanol extract from propolis is tested against Gram-positive bacteria Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus cereus, Gram-negative bacteria Pseudomonas aeruginosa, a yeast, Candida albicans, and a mold, Fusarium verticillioides. The growth of microbial colonies is observed for up to 120 h. The results show over 90% effect when treating paper with ethanol extract of propolis, which is an indication that it has significant potential for inclusion in antimicrobial active packaging materials.