Influence Of Ph And Different Emulsion Components On Stability And Physicochemical Properties Of Canola Oil-In-Water Emulsion \n

Field: Chemical Engineering (Physical Sciences)

The main objective of the present study was to investigate the effect of pH (5-7), \nprocessing conditions (i.e. pressure, cycle and temperature) and main emulsion \ncomponents (namely, propylene glycol, caseinate sodium, pectin, sodium chloride \nand canola oil) on the physicochemical properties of sodium caseinate-pectin \nstabilized emulsions. In this work, the physicochemical emulsion properties assessed \nby measuring the zeta-potential, average droplet size, apparent viscosity, turbidity, \nand creaming stability were considered as response variables. The results indicated \nthat the pH and temperature had significant (p < 0.1) effects on all the response \nvariables studied. The highest creaming stability was observed at pH 5, which was \nattributed to the formation of multilayer in the interfacial area. It was found that the \naverage droplet size increased when pH was increased from 5 to 7. The prepared emulsions showed shear-thinning behaviour at different pH values (5-7). The highest \nemulsion viscosity was also observed at pH 5; while it decreased when pH was \nincreased from 5.5 to 7. \nThe influence of processing conditions (i.e. pressure, cycle of high pressure \nhomogenizer and temperature of environment to solubilize the pectin) on the \nphysicochemical properties of sodium caseinate-pectin stabilized emulsions were \ninvestigated. The results indicated that the independent variables had the most and \nleast significant (p < 0.05) effect on average droplet size and stability, respectively. \nThe effect of cycle of the homogenizer was significant (p < 0.05) in all response \nvariables. The nonlinear regression equations were significantly (p < 0.05) fitted for \npredicting the changes in all the response variables with relatively high coefficient of \ndetermination (R2 > 0.825). It was concluded that desirable physicochemical \nproperties can be achieved when the pressure, cycle, and temperature of the pectin \nsolution were adjusted to 13 MPa, 3, and 80 ° C, respectively. \nIt was observed that the physicochemical properties of emulsions were significantly \n(p < 0.1) influenced by the concentration of pectin. It could be explained by the fact \nthat the presence of carboxyl groups (–COOH) in the molecular structure of pectin \nprovided the proper surface activity in the interfacial area. The pectin molecules \nadsorbed to the droplet surfaces and increased the repulsion forces between the \nemulsion onto droplets, thereby preventing extensive droplet flocculation. The zeta \npotential remained negative in all emulsion samples, possibly because of negatively charged (-COO-) groups presence in the molecular structure of pectin. The second \norder regression equations were significantly (p < 0.1) fitted for predicting the \nchanges in all the response variables with relatively high coefficient of determination \n(R2 > 0.7). The results indicated that the emulsion containing 0.9% (w/w) propylene \nglycol, 1.0% (w/w) sodium caseinate, 3.0% (w/w) pectin, 0.2% (w/w) sodium \nchloride and 15.0% (w/w) canola oil provided the optimum emulsion formulation \nwith desirable physicochemical properties. The adequacy of response surface \nequations was confirmed by indicating no significant (p > 0.1) difference between \nthe experimental and predicted values.