Optimization of a method designed to extract and characterize microplastics in different packaged fish products

International audienceThe study of the presence of microplastics (MPs) in seafood products is usually carried out by analyzing the gastrointestinal tract. However, this part is mostly removed during food processing. Moreover, few studies have produced results from processed fishery products. The primary objective of this study was to optimize methods for evaluating the presence of MPs in the edible portions of several products available in supermarkets. Seven seafood products, including smoked, canned, marinated, and those stored in polystyrene trays, were selected for analysis, with saithe fillets (Pollachius virens) and canned tuna (Thunnus alalunga) among them. To achieve optimal digestion of the samples, a 10% KOH solution at 40 °C was used. For the fattiest samples, such as marinated anchovies, hydrophobic filters were employed. Additionally, bleach was utilized to lighten dark filters obtained, ensuring readability under the microscope. These parameters were defined to obtain suitable methods for each product. The average concentrations in different seafood matrices ranged from 0.05 ± 0.04 to 0.33 ± 0.08 MP/g for saithe fillets and canned tuna, respectively. After extrapolation of these values to all the particles observed on each filter, the concentrations increased from 0.06 ± 0.05 MP/g to 2.17 ± 0.33 MP/g. Particles identification across all samples, using a microscope coupled with Fournier transform infrared spectroscopy (μ-FTIR), confirmed the presence of MPs, including PET, PP, and EVA