Detection of aflatoxin M1 in milk using spectroscopy and multivariate analyses

- Pure and contaminated samples differed in ranges 1423-1123 and 3550-3499 cm−1.
- PCA showed discrete clustering of samples based on level of AFM1.
- Developed models could correctly classify more than 86% test samples.
- Developed models could detect as low as 0.02 μg/l AFM1 in milk (p ⩽ 0.05).
- ATR-FTIR spectroscopy is a rapid method for assessing AFM1 in milk.

Aflatoxin M1 (AFM1), a potentially carcinogenic compound, is found in milk obtained from animals that consume contaminated feed. Spectra of bovine milk, spiked with AFM1 (0, 0.02, 0.04, 0.06, 0.08 and 0.1 μg/l) were acquired using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometer. Spectra revealed significant differences among pure and AFM1 spiked samples in spectral regions 1800-650 cm−1 and 3689-3499 cm−1, which may be attributed to complex chemical structure of AFM1. Principal component analysis (PCA) showed clear clustering of samples (p ⩽ 0.05). The models could successfully classify (>86%) and detect even 0.02 μg/l AFM1 in milk (p ⩽ 0.05) using SIMCA. AFM1 was best predicted in wavenumber range of 1800-650 cm−1 with coefficient of determination (R2) of 0.99 and 0.98, for calibration and validation, respectively, using partial least square (PLS) regression. The study indicated feasibility of ATR-FTIR spectroscopy and chemometrics in rapid detection and quantification of AFM1 in milk.