Electrical resistance tomography as a tool to understand the stability of dairy-based high-protein beverages

During the production of dairy-based drinks or their early storage months, there are no established chemical or physical indicators to reliably predict whether a specific beverage will remain stable throughout its intended shelf life or undergo premature destabilization. Consequently, the industry relies on observing physical changes, such as increased viscosity or particle size, to assess the shelf stability of milk protein concentrate-based low-acid beverages. This study aims to evaluate the effectiveness of the electrical resistance tomography in liner configuration in detecting destabilization in high-protein beverages (HPB). A formulation containing 8% protein (wt/wt) was prepared using 2 lots of milk protein concentrate and other ingredients to validate the method. The formulation was retort sterilized and stored at room temperature for up to 225 d. At regular intervals, the unshaken beverage bottle was carefully divided into 4 equal layers: layer 1 (top) through layer 4 (bottom). Physicochemical properties, including total protein (TP), soluble proteins, viscosity, and particle size, were analyzed in the separated layers. On d 0, the sample was homogeneous, with a mean (±SD) conductivity of 0.0998 ± 0.00 µS/cm across all layers. However, a significant increase in mean conductivity was observed across all layers from d 14 to d 88, followed by a sudden decrease on d 109. This was succeeded by another significant increase, lasting until d 225. By d 225, the TP content in layer 4 had risen from 7.86 ± 0.09 to 9.82 ± 0.69, which also contributed to the observed increase in overall conductivity. Moreover, the change in conductivity showed a positive correlation with the change in TP content across the layers. These findings suggest that electrical resistance tomography is a promising tool for detecting physicochemical changes in HPB and could effectively identify early-stage sedimentation in HPB.