Date of Award
Master of Science (MS)
Committee Member 1
Fernanda San Martin-Gonzalez
Committee Member 2
Committee Member 3
The use of natural biopolymer particles as Pickering stabilizers for oil-in-water emulsions was investigated. B-lactoglobulin microgels and B-lactoglobulin/pectin complexes were created by heating appropriate biopolymer solutions at pH 5.8 and 4.75, respectively. Resultant particles exhibited spherical morphology with diameters of 100-300 nm and possessed significant negative surface charge. Particles were first homogenized with 1% corn oil at 0.05%, 0.1% or 0.25% (wt/ wt) particle concentrations. All emulsions appeared stable over seven days with only a thin, creamed ring forming after several hours. Corn oil emulsions were most stable with 0.25% heated complexes, with volume-weighted mean droplet diameter remaining around 480 nm throughout seven days of storage. When the 0.25% heated complexes were dialyzed to remove the free, unaggregated protein, the corn oil emulsions that resulted initially had similar volume-weighted droplet diameters as the undialyzed emulsions until day three of storage when the emulsions created with dialyzed complexes began to grow in size, reaching over 1 micron at day seven of storage.
In order to examine the effects of particle stabilized-emulsions on volatilization rates, 1% of a 90:10 blend of limonene:corn oil was homogenized with 0.25% heated complexes. Again, turbid emulsions resulted with no visible creamed ring and a stable volume-weighted mean droplet diameter beginning around 620nm and growing to 800 nm at the end of the seven day storage. The heated complex particles displayed interfacial activity as indicated by increased surface pressure at a limonene: corn oil droplet interface by inverted pendant drop analysis. The unheated B-lactoglobulin/pectin complexes were able to quickly increase the surface tension and reach equilibrium. In contrast, the heated complex particles displayed two different slopes of adsorption, the first quickly increasing surface pressure while the second slope was a more gradual increase in surface pressure attributed to the larger aggregates. Headspace gas chromatography revealed that after one day, no significant difference was seen in limonene headspace concentration as compared to control emulsions stabilized by the commercial surfactant Tween 20.
Zimmerer, Laura Kathryn, "Pickering Stabilization of Oil-Water Interfaces by Heated B-lactoglobulin/Pectin Particles" (2013). Open Access Theses. 113.