Antimicrobial packaging based on linear low-density polyethylene compounded with potassium sorbate

- A new approach for compounding of LLDPE with potassium sorbate (KS) was introduced.
- KS presence in the polymer matrix significantly improves the thermal stability of the blends.
- KS release from the produced films follows Fickian diffusion rule.
- Glycerol monooleate, used as a dispersant, when mixed with KS, does not lead to significant viscosity reduction of the films.

In recent years much attention has been devoted to active packaging technologies that offer new opportunities for the food industry and food preservation. In the present study, antimicrobial films were developed by compounding of a neat linear low density polyethylene (LLDPE) or its blend with ethylene vinyl acetate (EVA), with potassium sorbate (KS). A new approach for preservative incorporation into a polyolefin matrix was used to obtain uniform dispersions of the preservative in the films. This approach includes using glycerol monooleate (GMO) as a dispersant and preparation of GMO/KS concentrate by strong mechanical mixing. The antimicrobial activity of the films was studied using the yeast strain Saccharomyces cerevisiae S288C. All compositions of LLDPE or LLDPE/EVA containing GMO and KS demonstrated antimicrobial activity. Release tests showed that KS migrates from compression molded 300 μm films to an acidic food simulant and its diffusion is controlled by the Fickian diffusion rule. Thermal stability, rheological behavior, morphology and KS dispersion in the polymer matrices of the prepared blends and films were investigated. The results indicate that the presence of KS in the polymer matrix significantly improves the thermal stability of the blends compared with the neat matrices without a significant viscosity reduction.