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Gel-in-oil-in-water emulsions offer stability for food processing applications.

Water-in-oil-in-water (WOW) multiple emulsions have, for many years, been the subject of research in order to utilize their functionality in foods and pharmaceuticals, for reduced fat formulation and taste masking, among other applications.

WOW emulsions will find a number of potential opportunities, especially in the area of fat reduction. These emulsions are a type of double or multiple emulsion.

There are two types of double emulsions: the WOW emulsion and its opposite, the oil-in-water-in-oil (OWO) emulsion. Among these two, the WOW emulsions are more relevant to food and supplement producers because most food systems are composed of a continuous aqueous phase, and not a continuous oil phase. WOW emulsions have three distinct phases. Internal water droplets are dispersed in an oil phase, which is enclosed in a continuous water phase.

However, their complex structure is susceptible to a broader range of instabilities than conventional emulsions. British scientists examined how different emulsifiers and a simple, novel approach to gel the internal aqueous droplets can optimize the emulsion's stability to heat, shear and the presence of salt.

Changes in salt concentration can be detrimental to multiple emulsions. These changes can cause a swelling or shrinkage of the internal water droplets in the emulsions. In their research, the scientists used polyglycerol polyricinoleate (PGPR) as the preferred low hydrophilic-lipophilic balance (HLB) emulsifier. Its presence dominated the stability of the WOW emulsions, irrespective of the high HLB emulsifier present.

However, the researchers found that lecithin was the most stable high-HLB emulsifier to heating. Gelling the internal water droplets with either alginate or carrageenan reduced the size of these droplets, which was probably the result of reduced rates of re-coalescence.

The resulting multiple gel-in-oil-in-water (GOW) emulsions were more stable than the WOW emulsions to the addition of up to 1% salt to the external phase. Also, the presence of xanthan gum in the external phase further improved the stability of the emulsions to the addition of salt.

In this manner, GOW emulsions have potential food processing applications, showing stability to shear, to temperature and to changes in salt concentration.

Further information. Peter Wilde, Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK; phone: +44 1603 255258; fax: +44 1603 507723; email: peter.wilde@ifr.ac.uk.

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Publication:Emerging Food R&D Report
Date:Sep 1, 2015
Words:373
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