Comparison of the Potential Abilities of Three Spectroscopy Methods: Near-Infrared, Mid-Infrared, and Molecular Fluorescence, to Predict Carotenoid, Vitamin and Fatty Acid Contents in Cow Milk

The objective of this work is to compare the ability of three spectroscopy techniques: molecular fluorescence, near-infrared (NIR), and mid-infrared with attenuated total reflectance (MIR-ATR) spectroscopy to predict the concentrations of 8 carotenoids, 6 vitamins and 22 fatty acids (FA) in cow's milk. A dataset was built through the analysis of 242 frozen milk samples from different experiments. The milk compounds were analysed using reference methods and by NIR, MIR-ATR, and fluorescence to establish different predictive models. NIR spectroscopy allowed for better prediction of cis9-beta-carotene, beta-cryptoxanthin and the sum of carotenoids than the other techniques, with a coefficient of cross-validation in calibration ((RCV)-C-2) > 0.60 and a coefficient of determination in validation ((RV)-V-2) > 0.50. Their standard errors of prediction (SEP) were equal to 0.01, except for the sum of carotenoids (SEP = 0.15). However, MIR-ATR and fluorescence seem usable for the prediction of lutein and all-trans-beta-carotene, respectively. These three spectroscopy methods did not allow us to predict ((RCV)-C-2 < 0.30) vitamin contents except, for vitamin A (the best (RCV)-C-2 = 0.65 with NIR and SEP = 0.15) and alpha-tocopherol (the best (RCV)-C-2 = 0.56 with MIR-ATR and SEP = 0.41), but all (RV)-V-2 were <0.30. NIR spectroscopy yielded the best prediction of the selected milk FA.