Rheological characterisation of thickened milk components (protein, lactose and minerals)

Thickened fluids are commonly used in the medical management of individuals who suffer swallowing difficulties (known as dysphagia). However, it is not always easy to obtain the correct consistency of thickened fluids. Variabilities can be due to thickening agents, solids content, and differences in dispersing medium. Thickened milk is a fluid that is commonly served for patients, but is one of the most complex fluids. This study examined the rheological characterisation of individual thickened milk components (protein, lactose and minerals) thickened with a commercial xanthan gum based thickener and investigated the effect of these components on the rheological behaviour of complete thickened milk. It was found that protein increased the final viscosity of the fluid but did not affect the dynamics of the thickening process. Conversely, mineral content significantly slowed down the thickening process, but only slightly increased the viscosity of the fluid. Lactose had no effect on either the dynamics of the thickening or on the final viscosity. This study confirms and explores the interactions between thickener and milk components in milk used for the medical and nutritional management of swallowing difficulties.