Rheological characterization of hydrocolloids interaction: A case study on sage seed gum-xanthan blends

In this paper, a first robust scheme for in-depth rheological study on the interaction of two attractive hydrocolloids (sage seed gum (SSG) and xanthan gum (XG) at five blending levels (1-0, 3-1, 1-1, 1-3, and 0-1)) was defined by utilizing flow behavior, thixotropy and viscoelasticity measurements. Shear thinning as the important rheological behavior of biopolymers were found to be broadly different in steady and dynamic shear tests. We attributed this difference to the longer timescale of segment-segment interaction in SSG chains than that of XG. A well-developed three-parametric exponential model satisfactory fitted the recovery phase data of in-shear structural recovery test. There was a negative correlation between time effects in SAOS (small amplitude oscillatory shear) and thixotropy with R-2 equal to -0.90. The highest recovery parameter (83.25%) and the lowest extent of time dependency (determined in SAOS) were obtained for XG. Excellent correlation existed between the extent of time dependency and the difference between static and dynamic yield stresses (R-2 = 94-96%). The highest and lowest departure values from Cox-Merz rule were found for SSG (83.87%) and XG (46.18%), respectively. The strongest interaction between SSG and XG among all ratios tested, occurred for 3-1, which was confirmed by the Cole-Cole plot. (C) 2016 Elsevier Ltd. All rights reserved.