Raman spectroscopy as a tool to identify modification of whey protein concentrate (WPC) during shelf life

Changes in the structure of lactose constitute the main physical modification of dairy powders and may lead to other changes during product storage. Raman spectroscopy was confirmed to be a viable analytical tool to aid in identifying the lactose state of whey protein concentrate (WPC) during production and storage. The dehydrated products obtained in this study had mean aw values greater than 0.200, indicating that changes in characteristics may occur rapidly during storage. The effects of different treatments and storage conditions on the crystallization of lactose were identified by spectral changes near 2900 cm−1 and between 1200 and 800 cm−1, attributed to the phase change of amorphous lactose into crystalline lactose. For samples stored at ambient temperature and humidity, changes in the Raman spectra occurred after three weeks of storage. For samples stored in desiccators, changes were not observed until one year of storage. As such, the presence of oxygen and moisture in the environment can increase the rate of modifications of WPC. The association between Raman spectroscopy and chemometrics may be considered a screening method for routine analysis or production line control. The results of this article provide an important tool for the dairy industries and for research in dairy concentrated and dried dairy products, enabling the development of sensors for dairy spray dryers to improve the control and the standardization of products and technology.