Flow properties of sweetened sesame paste (halawa tehineh)

Sweetened sesame paste, known as halawa tehineh, is a food product that consists of heat-treated sugar, citric acid and tehineh. Some natural flavor may be added, for instance vanilla and nuts. The steady and time-dependent flow properties of halawa tehineh were investigated in the temperature range between 25-45 degreesC. The flow behavior of halawa tehineh was observed to be pseudoplastic and thixotropic at all temperatures measured, and the apparent viscosity-shear rate data can be described by a power law model. Increasing the temperature increases the flow behavior index and significantly reduces the consistency coefficient. The temperature dependency of the consistency coefficient is given by an Arrhenius-type relationship. A second order structural kinetic model describes the thixotropic behavior of halawa tehineh well. An empirical equation was developed for predicting the rate of thixotropic structural breakdown as a function of shear rate and temperature.