Publication Date

Summer 2015

Advisor(s) - Committee Chair

John Khouryieh (Director), and Kevin Williams

Degree Program

Department of Chemistry

Degree Type

Master of Science

Abstract

Oil-in-water emulsions have wide range of applications in food industry because of their structure-forming properties, and as delivery systems of polyunsaturated fatty acids into foods. The thermodynamic instability of oil and water, and high susceptibility of unsaturated fatty acids to oxidation lead to physical and oxidative stability in oil-in-water emulsions. These instability processes are generally controlled by incorporating proteins and polysaccharides into oil-in-water emulsions. The objective of this study was to evaluate xanthan/enzymatically modified guar (XG/EMG) polysaccharides on the physical and oxidative stability of 2 wt% whey protein stabilized oil-in-water emulsions containing 20% v/v menhaden fish oil. Enzymatic modified guar gum was obtained by hydrolyzing native guar gum using α-galactosidase enzyme. Emulsions were prepared for guar gum (GG), xanthan gum (XG), xanthan/guar (XG/GG), and xanthan/enzymemodified guar (XG/EMG) gum mixtures using 0, 0.05, 0.1, 0.15, 0.2, and 0.3% gum concentrations. Emulsions were then evaluated for creaming, viscosity, particle size, and microstructure to evaluate the physical stability, and peroxide value, TBARS value and GC-MS solid phase micro extraction (SPME) experiments were performed to evaluate the oxidative stability. Emulsions containing XG/EMG gum mixtures exhibited better creaming stability and higher viscosity of all the emulsion types. However, XG/EMG gum concentrations did not affect the droplet size of the emulsions. The microstructures revealed decreased flocculation in emulsions with XG/EMG mixtures. The primary and secondary lipid oxidation measurements indicated that emulsions containing XG/EMG gum mixtures were more effective in preventing the lipid oxidation of all the emulsion types. From the results, it is evident that XG/EMG gum mixtures can be used as emulsifiers in oil-in-water emulsions to increase both physical and oxidative stability.

Disciplines

Chemistry | Food Chemistry | Food Science

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