Papers by Jelena Milinkovic
Journal of the Serbian Chemical Society, 2018
Pumpkin (Cucurbita pepo) seed protein hydrolysate (PSPH) was obtained by enzymatic hydrolysis of ... more Pumpkin (Cucurbita pepo) seed protein hydrolysate (PSPH) was obtained by enzymatic hydrolysis of pumpkin seed protein isolate using pepsin. Influence of pH (3, 5 and 8) and ionic strength, I c (0-1 mol dm-3), on the adsorption kinetics of PSPH (diffusion rate constant, k diff , and adsorption rate constant, k ads), interfacial pressure (π) and interfacial dilatational properties (dilatational elasticity, E′, and viscosity, E″) of the oil-PSPH solution interfaces was investigated at different PSPH concentrations (c = 0.0014-14 g dm-3). It was found that PSPH adsorbs to the interface at c ˃ 0.0014 g dm-3 , regardless of pH and ionic strength, as evidenced by the increase in interfacial pressure. The k diff and k ads value were found to be the highest at pH 3 and the lowest at pH 5 at the corresponding concentrations. The dilatational properties of the interfaces, which were investigated at different oscillation frequencies, ν, 0.01-0.2 Hz, showed that the E′ of the oil-PSPH solution interfaces is much higher than its E″. Moreover, E′ increases with increasing PSPH concentration at pH 5 and 8, and with increasing I c , regardless of the pH, while E″ changes only minimally.
Journal of the Serbian Chemical Society
Pumpkin (Cucurbita pepo) seed protein hydrolysate (PSPH) was obtained by enzymatic hydrolysis of ... more Pumpkin (Cucurbita pepo) seed protein hydrolysate (PSPH) was obtained by enzymatic hydrolysis of pumpkin seed protein isolate using pepsin. Influence of pH (3, 5 and 8) and ionic strength, Ic (0?1 mol dm-3), on the adsorption kinetics of PSPH (diffusion rate constant, kdiff, and adsorption rate constant, kads), interfacial pressure (?) and interfacial dilatational properties (dilatational elasticity, E?, and viscosity, E?) of the oil?PSPH solution interfaces was investigated at different PSPH concentrations (c = 0.0014?14 g dm-3). It was found that PSPH adsorbs to the interface at c ? 0.0014 g dm-3, regardless of pH and ionic strength, as evidenced by the increase in interfacial pressure. The kdiff and kads value were found to be the highest at pH 3 and the lowest at pH 5 at the corresponding concentrations. The dilatational properties of the interfaces, which were investigated at different oscillation frequencies, ?, 0.01?0.2 Hz, showed that the E? of the oil?PSPH solution interfac...
Journal of the Serbian Chemical Society, 2016
Polymer/surfactant association is a cooperative phenomenon where surfactant binds to the polymer ... more Polymer/surfactant association is a cooperative phenomenon where surfactant binds to the polymer in the form of aggregates, usually through electrostatic or hydrophobic forces. As already known, polyelectrolytes may interact with oppositely charged surfactants through electrostatic attraction that results in polymer/surfactant complex formation. This behavior could be desirable in wide range of application of polymer/surfactant mixtures, such as improving colloid stability, gelling, emulsification and microencapsulation. In the present study surface tension, turbidity, viscosity and electrophoretic mobility measurements were used to investigate interactions of cationic polyelectrolyte chitosan (Ch) and oppositely charged anionic surfactant, sodium dodecyl sulfate (SDS), in buffered water. Obtained results show the presence of interactions that lead to Ch/SDS complexes formation at all investigated pH and for all investigated polymer concentrations. Mechanisms of interaction, as well...
Acta Periodica Technologica
Water in oil (W/O) emulsions are dispersed systems which have very wide application as a carriers... more Water in oil (W/O) emulsions are dispersed systems which have very wide application as a carriers in the food, pharmaceutical and cosmetic industry products. The main problem with practical application of such systems is their low stability. The emulsifiers used to stabilize this type of emulsions are with low hydrophilic-lipophilic balance values. The present work examines the possibility of the application of mixtures of lipophilic emulsifiers polyglycerol polyricinoleate (PGPR) and polyglycerol fatty acid esters for stabilization of W/O emulsions. First of all, the adsorption properties of the used emulsifiers were examined by tensiometic measurements. Based on these results, two emulsifiers PGPR and decaglycerol decaoleate (Caprol 10G10O) were selected for the preparation of the emulsions, as well as their mass ratios and total concentrations. The results of the investigation of the emulsions properties (dispersion analysis and sedimentation stability) showed that more stable em...
Acta Periodica Technologica
Contemporary formulations of cosmetic and pharmaceutical emulsions may be achieved by using combi... more Contemporary formulations of cosmetic and pharmaceutical emulsions may be achieved by using combined polymer/surfactant system, which can form complexes with different structure and physicochemical properties. Such complexation can lead to additional stabilization of the emulsion products. For these reasons, the main goal of this study was to investigate the interfacial properties of chitosan/sodium dodecyl sulfate complexes. In order to understand the stabilization mechanism, the interface of the oil/water systems that contained mixtures of chitosan and sodium dodecyl sulfate, was studied by measuring the interfacial tension. Considering the fact that the properties of the oil phase has influence on the adsorption process, three different types of oil were investigated: medium-chain triglycerides (semi-synthetic oil), paraffin oil (mineral oil) and natural oil obtained from the grape seed. The surface tension measurements at the oil/water interface, for chitosan water solutions, in...
Acta Periodica Technologica
Water-in-oil (W/O) emulsions are dispersed systems which are often used in the pharmaceutical, co... more Water-in-oil (W/O) emulsions are dispersed systems which are often used in the pharmaceutical, cosmetic and food industries as products, or as carriers of active substances. It is well known that they are very unstable, so that selection of the emulsifier and properties of the oil and water phase are main factors affecting their stability. The aim of this paper was to examine the possibility of application of a lipophilic, polymeric emulsifier, PEG 30-dipolyhydroxystearate (Cithrol TM DPHS), for stabilization of W/O emulsions. Behaviour of the emulsifier at W/O interfaces was determined by means of tensiometry. A series of emulsions were prepared with 20% (w/w) of water and different types of oil. Droplet size, droplet size distribution, viscosity, and sedimentation stability during 30 days of storage at room temperature of the emulsions prepared with paraffin oil, olive oil, grape seed oil, and medium-chain triglycerides, stabilized with 1% Cithrol TM DPHS, were determined. All investigated emulsions were stable for 30 days, except the one prepared with paraffin oil. The results of this study confirmed that PEG 30-dipolyhydroxylstearate is a good emulsifier and stabilizer of W/O emulsions which contain different types of oil.
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Papers by Jelena Milinkovic