Commercial milk discrimination by fat content and animal origin using optical absorption and fluorescence spectroscopy

Distinguishing milk products by fat content and animal origin is important as it can address problems in quality control in the dairy industry and in adulteration testing for regulatory bodies. Optical spectroscopy, combined with statistical analysis methods, can be useful in such analyses, being fast, non-destructive and cheaper compared with conventional analytical methods. In this study we discriminate commercial (supermarket) cow, goat and sheep milk based on their fat content and animal origin, by applying three spectroscopic techniques: ultraviolet absorption, Fourier-transform infrared reflectance (FTIR) and fluorescence. Orthogonal partial least-squares discriminant analysis (OPLS-DA) of the data grouped the samples by animal origin and fat content. All techniques exhibit at least 70% success rates in grouping the samples. UV absorption works best in fat-based discrimination (96% success), while fluorescence and UV are the most successful in animal-based discrimination (both 91% success).