Recent advances in the analysis of dairy product quality using methods based on the interactions of light with matter

As demonstrated by physicists in the past centuries, light interacting with matter contains information that may reveal the concentration or/and the structure of components of the investigated matter. The use of spectroscopy (absorption in the visible, infrared, fluorescence, Raman, etc.) in food science has increased tremendously in the last couple of decades as it has been demonstrated that the detection and content of a number of food constituents, as well measurement of food properties, may be achieved by measuring the radiations that is either absorbed or emitted at different wavelengths by the product. These developments have been made possible, thanks to multivariate chemometric methods that are appropriate and useful for the evaluation of fluorescence or infrared spectra exhibiting slight differences such as the ones recorded on dairy products, allowing the development of prediction models. Recently, imaging technology such as confocal laser scanning microscopy or hyperspectral imaging coupled to image analysis techniques has successfully been used to study highly heterogeneous products such as cheese. Indeed, image analysis techniques such as mathematical morphology or image texture analysis make it possible to quantify structures in the images and to show the influence of different manufacturing processes on the protein network microstructure of cheeses. The aim of this article is to summarise those aspects of spectroscopy and imaging methods that may have value for solving problems in dairy science and technology.