Identification of milk fraud using laser-induced breakdown spectroscopy (LIBS)

Detection of milk adulteration is vital for fair trade and for protecting consumers from food fraud. The identification of species origin for milk was studied using laser-induced breakdown spectroscopy (LIBS) with the aid of chemometrics. Bovine, caprine and ovine milk samples were analysed with LIBS to determine their elemental composition differences. For classification of pure and adulterated milk samples, LIBS spectra were evaluated with principal component analysis (PCA), and partial least square regression (PLSR) was performed to determine adulteration ratios. For these analyses, milk samples were transformed into gels to increase the analytical performance of LIBS by eliminating splashing and low emission intensities encountered during measurement of liquids. The coefficient of determination (R2) and limit of detection (LOD) values for caprine milk adulteration with bovine milk were 0.995 and 1.39%, respectively; the corresponding values for ovine milk adulteration with bovine milk with were 0.996 and 1.29%, respectively.