Broadband Dielectric Spectroscopy (BDS) investigation of molecular relaxations in durum wheat dough at low temperatures and their relationship with rheological properties

Abstract

Broadband Dielectric Spectroscopy (BDS) was used to study the dielectric relaxation processes of semolina doughs. The dielectric properties were analyzed as a function of water content, and, additionally, the effects of NaCl presence and semolina characteristics were investigated. The dough was prepared using three different varieties of semolina. BDS measurements were conducted using a custom-made Rheo-dielectric tool composed of a Broadband Dielectric/Impedance Spectrometer connected to a strain-controlled rheometer. The temperature range investigated was from −135 °C to 25 °C, with a step of 5 °C, while the frequency range was 10−1 – 107 Hz. Dielectric spectroscopy turned out to be a valuable technique for dough characterization. It is capable to distinguish the carbohydrates contribution and the different interactions between water and dough components. Moreover, this unique combination allows assessing correlations between rheological and dielectric properties, like the compliance of dough as a function of the relaxation processes and the influence of semolina components.