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This study was aimed at evaluating the flow behavior characteristics of yogurt enriched with fish oil (FO) microcapsules prepared by complex coacervation method. FO was microencapsulated in gelatin-acacia gum coacervates. Then, the microcapsules were dried, and yogurt was produced from the milk enriched with microcapsules powder. Rheological characteristics (as measured using a rotational viscometer) of yogurt were evaluated in the shear rate range of 0.262-7.86 s^-1 at 6˚C during 21 days of storage. Power Law model was used for calculation of consistency coefficient and flow behavior index of yogurt. As compared to the control, the enriched yogurt had higher apparent viscosity. Consistency coefficients of the enriched and the control yogurts were in the range of 24.42-28.82 and 15.31-17.76 Pa sⁿ, respectively. Yogurt samples showed a non-Newtonian shear-thinning flow behavior. Addition of FO microcapsules to yogurt may be useful for improving its health-promoting effect and consistency.

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Complex coacervation is generated through electrostatic interaction between oppositely charged biopolymers (proteins and polysaccharides). Complexation via electrostatic interactions can lead to formation of soluble or insoluble complexes. In the current research, the production and characteristics of the complexes formed from whey protein concentrate (WPC) and gum tragacanth (GT) were evaluated. In order to find the optimum pH for complexation, absorbance of protein-polysaccharide mixtures were measured at a wide range of pH (2–8), Furthermore, particle size, zeta potential, microstructure and rheological properties of the complexes were investigated. Based on the results, the best condition to form complex between WPC and GT was found to be at pH=4.5. With Increasing the amount of GT up to 0.75% w/w in a constant protein concentration (0.5% w/w), the lowest and highest particle size for WPC- GT complex was found at protein: polysaccharide ratio of 1: 1 (3018 nm) and 10:1 (4070 nm), respectively. Zeta potential changed from +3.11 mV (0% gum tragacanth) to -6.82 mV due to addition of GT (0.75% w/w). Microscopic images showed the presence of separate spherical particles, except at the concentration of 0.05% w/w. The appropriate rheological model to predict flow behavior of complexes was depended on protein-polysaccharide ratio and the dominate flow behavior index was found to be shear thinning. Increasing of TG concentration lead to lower flow behavior index as well as higher apparent viscosity, consistency coefficient and the yield stress

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In this study, the complex coacervation of plantago major seed mucilage (PSM) and chitosan (CHI), two oppositely charged polysaccharides, was studied as a function of pH (8.0-2.0). Biopolymers concentration 1% and PSM:CHI ratio (10:90 to 90:10), according to electrical conductivity (EC) and turbidity analyses. The solution containing 1% biopolymers with PSM:CHI ratio of 85:15 resulted in maximum complex coacervation at the pHopt 3.7. The EC of biopolymers solutions increased by decreasing pH. The aforementioned optimum condition resulted coacervates with maximum particles size (7 μm) and minimum ζ-potential (+5.5 mV), which were observed as densely agglomerated macro-complexes with highest coacervation yield (87%).
These hydrogels be useful for encapsulation and delivery of drugs and (bio-) active compounds.