Authentication of cow diet by visible and infrared spectroscopy on dairy products

The authentication of farming practices by rapid analytical methods of milk and/or cheese has been a concern of dairy sectors since decades. Infrared spectroscopy (IR) techniques have been proposed as a strategic authentication tool due to their rapidity and low cost, which allow routine application. The objective of this review is therefore to give an overview of the researches on the authentication of the feeding practices of dairy cows using the spectroscopy (visible, near (NIR) and mid IR (MIR)) on milk and cheese. The IR techniques have been shown to be able to discriminate between milk or cheese from contrasting diets with a precision frequently higher than 90 %. The NIR alone has slightly lower accuracies than MIR, but VIS + NIR give performance similar to MIR. All the IR techniques significantly reduce their accuracy when trying to discriminate milk from less contrasted diets. To overcome this limit, recent advances that propose the use of MIR spectroscopy on milk to predict indicators of the proportion of different feeds in the diet of cows, have shown promising results, especially for the prediction of pasture feeding. An example of application at the scale of a territory of IR models giving indicators of dairy herd diet compositing is provided. Its strengths and limits for routine application are also analyzed.