Invited review: Use of infrared technologies for the assessment of dairy products—Applications and perspectives

Abstract

Dairy products are important sources of nutrients for human health and in recent years their consumption has increased worldwide. Therefore, the food industry is interested in applying analytical technologies that are more rapid and cost-effective than traditional laboratory analyses. Infrared spectroscopy accomplishes both criteria, making real-time determination feasible. However, it is crucial to ensure that prediction models are accurate before their implementation in the dairy industry. In the last 5 yr, several papers have investigated the feasibility of mid-and near-infrared spectroscopy to determine chemical composition and authenticity of dairy products. Most studies have dealt with cheese, and few with yogurt, butter, and milk powder. Also, the use of near-infrared (in reflectance or transmittance mode) has been more prevalent than mid-infrared spectroscopy. This review summarizes recent studies on infrared spectroscopy in dairy products focusing on difficult to determine chemical components such as fatty acids, minerals, and volatile compounds, as well as sensory attributes and ripening time. Promising equations have been developed despite the low concentration or the absence of specific absorption bands (or both) for these compounds.

Novel applications of infrared technologies in dairy industry

“…So far, the prediction models developed were usually cheese-specific, i.e. explicitly intended for a cheese type or a category of cheeses [10]. Due to the lower amount of water compared to milk, cheese prediction models are usually built using wavelengths in the NIRS region, so that the sample does not need to be grinded or liquated [10].…”

“…explicitly intended for a cheese type or a category of cheeses [10]. Due to the lower amount of water compared to milk, cheese prediction models are usually built using wavelengths in the NIRS region, so that the sample does not need to be grinded or liquated [10]. Unfortunately, information on the practical applications and performances of NIRS in dairy factories is generally scarce, due to industrial secrecy policies.…”

“…not related to specific absorptions bands. Among these traits, minerals, fatty acids, cholesterol, volatile compounds and sensory properties stand out [10]. For example, some authors evaluated the potential of NIRS to predict the total antioxidant capacity of different cheeses, ending up with positive conclusions and perspectives [36].…”

“…It is possible to obtain an indirect determination of inorganic constituents if they are able to produce alterations of the water spectrum; e.g. Ca, Mg, and P are part of organic complexes in casein micelles and are thus predictable in both milk and cheese [10,11]. However, the accuracy of prediction is lower for traits that are not directly linked to an absorption infrared region or to organic molecules, and whose reference values are obtained through a subjective evaluation, such as sensory traits in cheese [10].…”

“…Ca, Mg, and P are part of organic complexes in casein micelles and are thus predictable in both milk and cheese [10,11]. However, the accuracy of prediction is lower for traits that are not directly linked to an absorption infrared region or to organic molecules, and whose reference values are obtained through a subjective evaluation, such as sensory traits in cheese [10]. In terms of accuracy, it is important to consider that the prediction model for the same trait can provide different results according to sample preparation, instrument used to collect spectra and wavelength range considered [12,13].…”