Fiber-based food packaging materials in view of bacterial growth and survival capacities

Paul Jakob Schmid; Stephanie Maitz; Nadine Plank; Elisabeth Knaipp; Sabine Pölzl; Clemens Kittinger

doi:10.3389/fmicb.2023.1099906

Fiber-based food packaging materials in view of bacterial growth and survival capacities

Front Microbiol. 2023 Jan 26:14:1099906. doi: 10.3389/fmicb.2023.1099906. eCollection 2023.

Authors

Paul Jakob Schmid¹, Stephanie Maitz¹, Nadine Plank¹, Elisabeth Knaipp¹, Sabine Pölzl¹, Clemens Kittinger¹

Affiliation

¹ Diagnostic and Research Institute of Hygiene, Microbiology and Environmental Medicine, Diagnostic and Research Center for Molecular Biomedicine, Medical University of Graz, Graz, Austria.

Abstract

Understanding interactions of bacteria with fiber-based packaging materials is fundamental for appropriate food packaging. We propose a laboratory model to evaluate microbial growth and survival in liquid media solely consisting of packaging materials with different fiber types. We evaluated food contaminating species (Escherichia coli, Staphylococcus aureus, Bacillus cereus), two packaging material isolates and bacterial endospores for their growth abilities. Growth capacities differed substantially between the samples as well as between bacterial strains. Growth and survival were strongest for the packaging material entirely made of recycled fibers (secondary food packaging) with up to 10.8 log₁₀ CFU/ml for the packaging isolates. Among the food contaminating species, B. cereus and E. coli could grow in the sample of entirely recycled fibers with maxima of 6.1 log₁₀ and 8.6 log₁₀ CFU/mL, respectively. Escherichia coli was the only species that was able to grow in bleached fresh fibers up to 7.0 log₁₀ CFU/mL. Staphylococcus aureus perished in all samples and was undetectable after 1-6 days after inoculation, depending on the sample. The packaging material strains were isolated from recycled fibers and could grow only in samples containing recycled fibers, indicating an adaption to this environment. Spores germinated only in the completely recycled sample. Additionally, microbial digestion of cellulose and xylan might not be a crucial factor for growth. This is the first study describing bacterial growth in food packaging materials itself and proposing functionalization strategies toward active food packaging through pH-lowering.

Keywords: bacterial growth; cellulose; endospores; food contamination; food packaging; packaging material; survival.