Development of active edible films from coffee pulp pectin, propolis, and honey with improved mechanical, functional, antioxidant, and antimicrobial properties

Abstract

This study examined the impact of propolis and honey on the physicochemical, structural, antioxidant, and antibacterial properties of coffee pulp pectin-based edible films. The films were made from pure pectin (P) and mixtures of pectin-glycerol (PG), pectin-propolis-glycerol (PPG), and pectin-honey (PH). Pectin solutions were prepared by varying the pectin-to-water ratio between 1 % and 5 % (w_pectin/v_water). Propolis, glycerol, and honey were then added to the solution, with the ratio of these ingredients to pectin ranging from 0 % to 60 %. The films were characterized for their physicochemical, structural, antioxidant, and antibacterial properties. The results showed that films made from 2 % pectin (P), 2 % pectin with 20 % propolis and 20 % glycerol (PPG), 2 % pectin with 20 % honey (PH), and 2 % pectin with 20 % glycerol (PG) exhibited higher elongation at break and better tensile strength. Higher pectin, honey, and glycol concentrations increase the film thickness. Similarly, Young's modulus increased with rising pectin concentration. The tensile strength of the films increased with glycerol concentration up to 20 %, after which it decreased. Young's modulus decreased with increasing glycerol concentration. Tensile strength and elongation at break improved with honey-to-pectin ratios up to 20 %, then declined with further increases. The water vapor permeability (WVP) values of the edible films ranged from 3.154 to 3.437 × 10⁻¹⁰ g/m·s·Pa. The films were fully degraded in soil within 9 days. The results suggest that adding honey and propolis enhanced the antioxidant and antibacterial properties of the films.