Whey protein nanoparticles prepared with desolvation with ethanol: Characterization, thermal stability and interfacial behavior
ABSTRACT Whey protein isolate (WPI) nanoparticles were prepared by diluting an alkaline solution of protein in ethanol at concentrations varying between 50 and 80%. The nanoparticles were then immediately diluted in buffer. While the nanoparticles were not stable at pH 7, they showed no changes in size when diluted at pH 3. When 75e80% ethanol was added during preparation, the size of the WPI nanoparticles ranged between 10 and 100 nm, with no change in size after dilution and storage at pH 3 for 96 h at 22 C. When heating was applied, particle aggregation occurred, and large aggregates (>1 mm) were observed at temperatures > 60 C. The particle size of the heat-induced aggregates could be reduced by homoge-nization. The nanoparticles prepared by desolvation showed interfacial pressure values similar to those of the corresponding protein solutions, indicating similar interfacial properties and the potential to be used to stabilize emulsions but as supramolecular aggregates of WPI.
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ABSTRACT: An alkaline solution of whey protein isolate was charged with absolute ethanol resulting in precipitation of whey protein particles. The vacuum-dried particles were then dispersed either in water or aqueous ethanol. Heat-treatment of whey proteins before desolvation process decreased the mean size of particles when dispersed in aqueous ethanol from 280 nm to 183 nm. The range and mean size of particles prepared from heat-treated protein solution when dispersed in water were 41–212 nm and 103 nm, respectively. Date palm pit aqueous extract was encapsulated inside the particulating heat-treated whey proteins during the desolvation stage with encapsulation efficiency of ~ 78%. Extract-loaded particles had mean size of 163 nm in alcoholic dispersion and 92 nm in water dispersion. Scanning electron microscopy imaging showed spherical nanoparticles aggregated in dry state. Fourier transform infrared spectroscopy suggested that extract and whey proteins did not covalently bind. Heat-treatment of whey proteins before desolvation resulted in the absence of denaturation endotherm in differential scanning calorimetry curve of extract-free particles. Extract loading in particles interrupted the continuity of protein matrix causing the occurrence of mild glass transition phenomenon in extract-loaded particles when heated.Food Research International 05/2013; 51(2):866–871. · 3.05 Impact Factor
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ABSTRACT: Abstract Whey proteins were inter-connected either by the enzyme transglutaminase or citric acid and then desolvated with ethanol to generate particles. Both samples comprised of sub-micron (>300 nm) and nano-scaled (∼100 nm) particles based on the hydrodynamic size measurements. Enzyme-induced cross-linking of proteins yielded more monodisperse particles and decreased the mean size of the major (nano-scaled) fraction of particles. Scanning electron microscopy images revealed a spherical morphology for all samples with mean sizes of <40 nm. Atomic force microscopy indicated a lower height for the particles from enzymatically cross-linked proteins. The mediating role of citric acid in bridging the proteins was confirmed by Fourier transform infrared spectroscopy. Differential scanning calorimetry indicated that pre-heating of protein solution before cross-linking and desolvation denatured the proteins entirely. In vitro degradation of whey protein particles in a simulated gastric fluid demonstrated that cross-linking of whey proteins before desolvation stage enhanced significantly the digestion stability of particles.Journal of Microencapsulation 04/2014; · 1.57 Impact Factor