Experimental Design to optimize protocols for the extraction and analytical detection of microplastics in lipid-rich food matrices

Microplastics (MPs) in food raises concerns about human exposure through ingestion. Reliable identification of MPs in lipid-rich matrices remains challenging due to inefficient digestion and spectral interference during Fourier-Transform Infrared (FTIR) spectroscopic analysis [1]. A Design of Experiments (DoE) approach was applied to optimize MP extraction protocols in fish at different lipid content, namely salmon, tuna, and cod. Recovery percentage and carbonyl index (CI) were used as proxies for extraction efficiency and residual lipid interference in absorbance spectra [2]. Screening Design and Response Surface Methodology allowed evaluation of digestion time, temperature, and solvent type effects. Specific optimal conditions (“sweet spot”) were identified as: Lipase at 60°C for 30 h for salmon, 10% KOH at 45°C for 40 h for tuna, and 10% KOH at 55°C for 36 h for cod, achieving high recoveries and low CI values together with reliable chemical characterization. Analysis of real fish samples confirmed MPs contamination with abundances ranging 0.7-2.9 items/g of dry weight. This DoE-based approach provides a reliable and sustainable strategy for MP analysis in food, contributing to improved standardization and risk assessment. The effectiveness of DoE for optimizing MPs extraction in complex food matrices was demonstrated, and highlighting the need for matrix-specific analytical protocols to support harmonized food safety assessments.