Rheological characterization of low fat sesame paste blended with date syrup

Abstract

In this paper, the time-dependent flow behavior of reduced fat sesame paste with date syrup were assessed using Brookfield rotational viscometer as a function of fat substitutes (guar gum, xanthan, and starch) at three levels and shearing time. Two models were used to predict the time-dependent behavior, known as, first-order stress decay with a zero equilibrium stress and Weltman models. It was found that time-dependent behavior of samples was adequately fitted with these models. All blends exhibited the thixotropic behavior and thixotropy of samples increased with increasing shear rate. For Weltman model, the A and B constants appeared in the range of 189.2-730.6 Pa and 0.090-1.571 Pa, respectively. While for first-order stress decay model, the initial shear stress (0) was in the range of 197-794 Pa, and the breakdown rate constant (K) varied in the range of 0.002-0.018 s-1. The presence of fat substitutes generally resulted in an increase of viscosity and thixotropy of blends in comparison with the blank.