Journal
FOOD HYDROCOLLOIDS
Volume 38, Issue -, Pages 119-128Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.foodhyd.2013.11.016
Keywords
Sodium alginate (SA); Cross model; Flow behavior; Thixotropy; Dynamical viscoelasticity; Multiwave temperature ramp test
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Funding
- Ministry of Science and Technology of China [2012BAD20B06-07]
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Understanding of the rheological behavior of sodium alginate (SA) is fundamental either to design optimized products or to ensure stable flows. Of the SA samples tested that characterized by a M/G ratio of 0.38 and a weight-average molecular mass (Mw) of 1.180 x 10(5) g/mol, steady-shear flow, thixotropy and dynamical viscoelasticity tests were carried out to characterize rheological behavior of G-rich SA aqueous solutions as influenced by concentration (1.0-3.0%, w/v) and temperature (5-35 degrees C). These measurements were carried out by using an Anton Paar-Physica MCR 301 Rheometer. It was found that, above a critical shear rate, all G-rich SA solutions (1.0-3.0%, w/v) exhibited non-Newtonian shear-thinning behavior and the flow curves could be well described by the Cross model. The temperature-dependent behavior of 2.5% (w/v) SA had higher correlation to the Cross model and the Arrhenius relationship, while the flow activation energy tended to decrease with the increase of shear rate. The upward-downward rheograms showed that all the systems evaluated in this paper had a hysteresis loop which indicating strong thixotropic behavior, the higher the SA concentration, the stronger the thixotropic behavior. The dynamical viscoelastic properties characterized by oscillatory frequency sweep under small-deformation conditions showed a fluid-like viscoelastic behavior. The behavior of SA aqueous solutions was predominantly more viscous than elastic. Multiwave temperature ramp test for 2.5% SA aqueous solutions was consistent with the results from oscillatory frequency sweep test. (C) 2013 Elsevier Ltd. All rights reserved.
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