Enmin Chen,Lianqi Cao,David Julian McClements,Shilin Liu,Bin Li,Yan Li
The impact of incorporating different levels of cinnamaldehyde (CA) into the oil phase used to prepare whey protein isolate (WPI)-stabilized nanoemulsions was investigated. Stable nanoemulsions could not be formed by pure CA, which was attributed to gravitational separation, but they could be formed from mixtures of CA and triglycerides. The mean particle diameter produced by homogenization decreased with increasing CA, which was attributed to the reduction of oil phase interfacial tension and viscosity. CA enhanced the physical stability of the nanoemulsions to salt addition (0–500 mM) and thermal processing (30–90 °C), but could not prevent droplet flocculation near the protein's isoelectric point (around pH 5). SDS-PAGE and surface load measurements indicated that more protein accumulated at the droplet surfaces in the presence of CA, which was attributed to interfacial crosslinking. CA may therefore be a useful means of modulating the physicochemical properties of protein-stabilized nanoemulsions.
A series of polymeric surfactants , poly acrylic acid rosin polyethylene glycol esters (P-AAR-PEG), have been synthesized from natural diterpenic rosin. Their structures were characterized by Fourier Transform Infrared Spectrometer (FTIR) and their molecular weights were characterized by Gel Permeation Chromatography (GPC). Their critical micelle concentration (CMC), surface tension (γ CMC ), foaming property (FP), and hydrophile-lipophile balance (HLB) value were evaluated. Their thermal properties were measured by Thermal Gravimetric Analyzer (TGA) and fluid behaviors were studied by Rotational Rheometer. The influence of concentration on the properties of oil-in-water emulsions was examined and contrasted the stability of emulsion by the mean droplet size between day1 and day7. The weight-average molecular weight of P-AAR-PEG ranged from 1770 to 5071. CMC values of P-AAR-PEG were ranged from 0.33 to 0.87 g/L and the corresponding γ CMC values were ranged from 37.8 to 39.1 mN/m respectively. Their CMC and γ CMC values decreased and then increased with the increment of molecular weight of hydrophile group. Rheological measurements indicated that the P-AAR-PEG solutions changed from pseudoplastic property to Newtonian with increasing shear rate. P-AAR-PEG1000 had good emulsion ability to turpentine in water. When the concentration of P-AAR-PEG1000 was 8 wt%, the emulsion remained stable for more than 7 days.
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