Enhancement effect on apparent viscosity of aqueous tragacanth gum dispersions promoted by sugars

Abstract

Flow curves of aqueous dispersions of tragacanth gum (T) with sucrose and glucose at different temperatures were determined using a controlled-stress rheometer. The effect of sodium chloride without or with sucrose (at the highest content) on the rheology of T dispersions was evaluated. The presence of sucrose and glucose promoted a noticeable enhancement impact on the apparent viscosity of aqueous T dispersions, which depended on sugar type/content, shear rate and temperature. In all cases, the glucose addition led to the largest enhanced viscosities at low shear rates (<10 s À1 ) and temperature. The joint action of sugar and salt exhibited a notable effect on apparent viscosity at low shear rates, softening the strong shear-thinning behaviour of T samples. Flow curves of T in the presence of sugars were satisfactorily described by the Cross-Williamson model, being semi-empirical correlations of the model parameters with ingredients content and temperature stablished.

Green Extraction of Carrageenans from Mastocarpus stellatus

“…This behavior is consistent with those results previously found for viscoelastic features of these hybrid carrageenans, where the gelling ability to form gels and their potential in the synthesis of nanoparticles was assessed [31]. The correspondence between experimental data from steady shear and oscillatory measurements using Cox-Merz rule was verified for tested hybrid carrageenan content throughout the similar shear-thinning behavior between dynamic and complex viscosities; however, superposition does not occur, as previously reported for other gelling polymers [42]. The magnitude of obtained values for viscoelastic moduli is comparable with those previously reported for other k/i-hybrid carrageenans under conventional treatments in the absence [32][33][34][35] and presence [41] of alkali processing during extraction.…”

Effect of CO2 nanobubbles incorporation on the viscosity reduction of fruit juice concentrate and vegetable oil

“…Viscosity is an important parameter of liquid foods (Magerramov et al ., 2007; Viswanath et al ., 2007). This property is widely considered and applied across industries to design food processes (Magerramov et al ., 2007); control qualities of food products (Silva et al ., 2017) and understand the rheological properties of food materials (Afoakwa et al ., 2009). Especially, with respect to handling processes involving high viscous liquid medium, there is a major concern about the efficiency of food manufacturing lines due to higher pumping power and operational cost required to transfer the fluid in processing facilities (Viswanath et al ., 2007; Amamcharla et al ., 2017).…”