A preliminary study in milk to discriminate goat feeding regimes by FTIR and chemometrics

In free-range (extensive) dairy farming the wealth and type of consumed vegetation positively affects milk characteristics such as flavour. As free-range feeding is included as a requirement in the specifications of certain protected designation of origin cheeses, there is a need to develop methodology to identify different animal feeding regimes. This study evaluated goat milk based on two feeding regimes, namely free-range and intensive (controlled diet fed exclusively at the farm). Conventional mid-infrared spectroscopy (4000-400 cm^-1) using Fourier transformed infrared technology was assessed for the discrimination of 65 milk samples obtained during spring time from the same dairy farm and breed of animals, which could be categorized as intensive and free-range feeding regimes. Chemometric analysis, whereby a supervised method of orthogonal partial least-square-discriminant analysis was applied, was shown to be essential for interpreting the spectroscopic data. The produced model returned distinct clusters of the two milk types, intensive and free-range with 95.4% correct classification accuracy.