Microplastic contamination in cheese from traditional and industrial production systems

The widespread presence of microplastics in food products, including dairy products, has raised concerns about contamination in cheese. This study characterized microplastics in six Slovak cheeses produced by traditional sheep cheese producers, small-scale minidairies, and industrial dairies. All cheeses were manufactured by our team directly in the respective dairies using standard processing steps typical for each production system. This work represents the first study to directly compare microplastic contamination across these three distinct dairy production systems. Samples were processed using a protocol comprising chelation, alkaline digestion, oxidative treatment, and sequential filtration. Particles retained on gold-coated membranes were analysed directly using laser direct infrared imaging, enabling automated polymer classification and morphometric characterization. Microplastics were detected in all samples, with blank-corrected synthetic microparticle counts ranging from 249 to 1,548 particles per sample. A total of 18 particle categories were identified, comprising various synthetic microplastic polymers-with polyethylene, polyamide, and polypropylene being the most prevalent-as well as natural or non-polymeric particles representing common environmental and processing-related impurities. Across all samples, microplastics were overwhelmingly dominated by fragment-shaped particles (typically > 80%), These findings suggest that dairy processing, equipment, and packaging materials may contribute to microplastic contamination, while the detection of microplastics in traditionally produced cheeses points to additional environmental exposure pathways. The study underscores the need for systematic monitoring within dairy supply chains, the development of food-grade plastic alternatives, and improved contamination-control practices. The results also provide an initial basis for evaluating dietary exposure to microplastics from cheese products.