Fusion of near-infrared and mid-infrared spectroscopy for the analysis of typical microplastic contaminants in powdered camel milk

Microplastics (MPs) are emerging contaminants that pose potential health risks through bioaccumulation. Efficient detection of MPs in complex food matrices, such as high-value camel milk powder (CMP), is critical for food safety. This study investigated the feasibility of using Near-Infrared (NIRS) and Mid-Infrared Spectroscopy (MIRS) combined with data fusion strategy for the rapid qualitative and quantitative analysis of MPs in CMP. Samples with MP concentrations (PP, PE, PET, PS) ranging from 0.01% to 1.00% (w/w) were prepared. The PCA results demonstrated that NIRS and MIRS provide complementary information. NIRS primarily captures overtones and combination bands of fundamental molecular vibrations, whereas MIRS detects fundamental vibrational modes that offer specific structural fingerprints. For qualitative analysis, the PLS-DA model based on low-level fusion achieved the best performance with 100% classification accuracy. For quantitative analysis, mid-level fusion yielded the most robust PLS models, with R 2 CV for PE, PET, PP, and PS reaching 0.745, 0.855, 0.911, and 0.906, respectively. This study establishes a novel, non-destructive, and efficient approach for monitoring microplastic contamination in CMP.