Exploring the feasibility of biodegradable films for antimicrobial absorbent sachets and CO2 emitters as sustainable active packaging

The use of biodegradable polymer films for packaging materials as eco-friendly alternatives to traditional plastics is limited by their water sensitivity and poor gas barrier properties. This study developed a multifunctional supplemental packaging system using poly(butylene adipate-co-terephthalate) (PBAT) and thermoplastic starch (TPS) blend film incorporated with 3% and 5% zinc oxide (ZnO) nanoparticles. The system targets the triple-active packaging displayed antimicrobial activity with water absorption and CO₂ emission properties. ZnO incorporation effectively reduced water solubility of the PBAT/TPS film (from 16% to 7%), and exhibited excellent antimicrobial activity against Gram-positive and Gram-negative bacteria (>99% reduction). Well-dispersed ZnO, verified by scanning electron microscopy, decreased water vapor and CO₂ gas permeation. A PBAT/TPS-ZnO sachet was fabricated, comprising carboxymethyl cellulose as the absorbent function and CO₂ precursors (sodium bicarbonate and citric acid). The 3% ZnO loading achieved optimal performance, balancing water absorption (2.48 g weight gain after 144 h) and CO₂ emission (35% in headspace at equilibrium). Kinetic studies suggested diffusion as the dominant mechanism for CO₂ release, driven by concentration differences between the sachet and headspace. This system showed potential as active modified atmosphere packaging to extend product shelf life.