Stress–dielectric relationships in Nutella

• A novel approach – dielectrostriction measurement was proposed for food rheological study.
• The relationship between dielectric and rheological responses of Nutella was studied during shear flow.
• Above a critical stress, the change in dielectric constant increased linearly with stress for Nutella.
• The first stress–dielectric coefficient can be obtained by using two differently oriented planar capacitive sensors.

Dielectrostriction is a rheodielectric phenomenon that describes the variation of dielectric properties of a material with deformation and is a fundamental property of any dielectric material. During the study of the dielectrostriction phenomenon in polymers, it was found that under small deformations a linear relationship exists between the change in dielectric constant and the stress. Like polymers, most foods are dielectric materials; hence, a change in their dielectric properties with deformation can be expected as well. In this study, the dielectrostriction effect was investigated in food for the first time. Nutella was chosen for this study. It has been found that a linear stress–dielectric relationship exists in Nutella during shear flow. The potential applications of the stress–dielectric relationship in food rheology and processing control are discussed.