The effect of starch modification and concentration on steady-state and dynamic rheology of meat emulsions
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In this study, the effect of starch modification (NPS, native potato starch; AMS, acid modified starch; DMS, dextrinized modified starch; PGS, pre-gelatinized modified starch) and its concentrations (1, 2, 4wt%) on steady-state and dynamic rheological properties of meat emulsions were determined. Water-oil binding capacity and intrinsic viscosity of potato starch increased up to 5.07-0.90g/g, and 14.98mL/g, respectively, after modifying with pre-gelatinization method. The particle size of starches as average mean diameter ranged between 44.19?m and 293.06?m. The maximum solubility was obtained from DMS after heat treatment at 70°C being 48.22%, which means an increase about 3.06-fold in solubility as compared with NPS. The Ostwald-de Waele model was successfully used to describe the flow properties of meat emulsions (R2>0.961). While starch types did not affect the K values of emulsions (p>0.05), starch concentrations did (p<0.01). All studied emulsions exhibited non-Newtonian, pseudoplastic behavior since n values were lower than 1. Emulsion systems were characterized as weak gel-like macromolecular dispersions with storage modulus (G') much greater than loss modulus (G?). A modified Cox-Merz rule was applied by multiplying angular frequency with shift factors (?SF). Frequency dependence of complex modulus (G*) was studied to measure the strength of cross-linking protein network of emulsion systems by calculating a constant order of relaxation function (?) and concentration dependent stiffness parameter (A?). It was concluded that PGS addition improved rheological properties of meat emulsions due to higher solubility, particle size, intrinsic viscosity, water-oil binding capacity than NPS. © 2015 Elsevier Ltd.