Emulsion design for protection of chemically sensitive bioactive ingredients

Kargar, Maryam (2014). Emulsion design for protection of chemically sensitive bioactive ingredients. University of Birmingham. Ph.D.

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Abstract

Lipid oxidation is a major issue for food manufacturers resulting in alteration of taste and appearance of product. In recent years, the food industry has been facing a tremendous pressure from consumers for using chemical agents to prevent lipid oxidation. In this study a novel approach to reduce lipid oxidation in oil-in-water emulsions has been taken and involves the manipulation of the emulsions' interfacial microstructure. Initially, oil-in-water emulsions were prepared with silica particles. The lipid oxidative stability was improved by up to 50%, compared with the emulsions stabilised by surfactant. However, silica particles are not “label friendly” hence; Modified Starch and colloidal Microcrystalline Cellulose were used as the “food-grade” Pickering particles. These samples had great stability against coalescence and the oxidation rate was reduced by up to 75%, compared with the emulsions stabilised by surfactant. The potential ability of fat crystal at the droplet interface to enhance the oxidative stability was also investigated. This was carried out by stabilising oil-in-water emulsions with saturated monoglyceride in the presence of xanthan gum. A bench scale scraped-surface heat exchanger was used to produce these emulsions. Solid fat crystals “shells” were created around the oil droplets by oscillating the temperature during emulsification. It was shown that these “shells” were capable of inhibiting the lipid oxidation by preventing pro-oxidants to come into close contact with the oil droplets.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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