Development of qualitative and quantitative analysis for the assessment of microplastics in food products

The presence of microplastics in the environment has increasingly attracted the attention of the scientific community due to their widespread distribution, persistence, and potential adverse effects on human health. Although numerous studies have investigated microplastics in water and seafood, information on animal-based foods remains limited, despite their crucial role in human diet. With this background, the objectives of the present Ph.D. thesis were: i) to investigate the occurrence, characteristics, and potential sources of microplastic contamination in milk and dairy products; ii) to assess microplastic contamination in skim-milk powders; and iii) to characterize microplastics in beef hamburgers. The Chapter 1 addressed microplastic contamination in milk, fresh cheese, and ripened cheese, with the dual aim of qualitatively and quantitatively characterizing the microplastics present and comparing contamination levels across these different dairy matrices. The Chapter 2 extended the investigation to skim-milk powders used for cheesemaking across European countries, applying a specific analytical protocol to identify plastic particles and evaluate the extent of contamination in this widely used food ingredient. Finally, the Chapter 3 expanded the investigation to beef hamburgers, aiming to provide insights into the occurrence and heterogeneity of microplastics in processed animal-based foods. The results of this doctoral thesis confirm, as expected for most food products, that microplastics are also widespread in foods of animal origin, including processed dairy and meat products. Considering the variability in their presence, morphology, and polymer types, the findings highlight the need for further research aimed at validating the outcomes of this study, investigating the main sources of contamination, and identifying effective strategies to reduce the occurrence of microplastics arising from the processing of raw materials into marketed products.