Aeration of oils in the presence of both edible and non-edible surfactants

Garvey, Emma Jayne

November 2014

Thesis or dissertation

© 2014 Emma Jayne Garvey. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

Unlike aqueous foams, very little literature exists in the area of non-aqueous foams despite this being an important field industrially, e.g. in confectionary manufacture and in the oil industry. Since the air-oil surface tension is normally at least half that of the air-water surface tension, the driving force for the adsorption of surfactant at the air-oil surface is significantly lower. The foamability and foam stability of mixtures of surfactants in oil have been investigated in an effort to understand how to control the amount and stability of such foams. The surfactants studied include phospholipids, monoglycerides, diglycerides, fatty acids and alcohols in numerous oils. Incorporation of gases of different types (including air, carbon dioxide and nitrous oxide) has been achieved using different methods. These include aeration by a thermostatted foaming column and the dissolving of gas into a system via a soda siphon. Temperature effects have also been investigated with aerations conducted at 25, 45 and 60 °C amongst other temperatures. The effect of the saturation of diglycerides has also been studied.

The solubility differences of the gases in oil no doubt influenced the process of disproportionation of bubbles, although drainage of oil and coalescence of bubbles occurs also. The foam half-life varied from minutes to months depending on the system composition. The effect of temperature was also found to influence the stability of the foam produced; in the case of compressed air as temperature increases foam stability

A whipped oil has also been produced with numerous two-component systems which has a stability of over 18 months. The formation of a gel was clearly important for the whipped oil production. Therefore the viscosity, solid content and solid surfactant size of the gel has been studied. It was clear through numerous investigations that temperature was crucial for foam formation and subsequent foam stability. Factors investigated were the effect of fatty acids and fatty alcohol chain length which highlighted the importance of the viscosity and solid content of a mixture prior to aeration for foam production. The basic behaviour of foams and previous relevant work in the area, along with results obtained are discussed in this thesis.

Department of Chemistry, The University of Hull
Binks, Bernard P.
Sponsor (Organisation)
Biotechnology and Biological Sciences Research Council (Great Britain); Nestlé Product Technology Centre York
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