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‘Lumpy micro-rods’ to enrich and structure food foams

By Stephen Daniells , 03-Nov-2009

Simple micro-rods made from food grade polymers can not only stabilise food foams, but also encapsulate bioactive ingredients for added value, suggests a new study supported by Unilever.

Researchers from the University of Hull and Unilever Research Vlaardingen used ethyl cellulose (E462) or shellac to prepare micro-rods that, when incorporated in a food foam, not only control the release of bioactive ingredients like fish oil, but also play a role in structuring and stabilising the food product.

Talking to FoodNavigator.com, lead researcher Vesselin Paunov from the Surfactant and Colloid Group in the School of Chemistry at the University of Hull, UK, said: “I see great potential for these micro-rods." While producing stable emulsions in foods is not a problem, producing stable foams is a “completely different business”, said Dr Paunov.

“If we make micro-rods of a few hundred nanometres in diameters and several tens of micrometres in length, we can stabilise emulsion droplets and bubbles that are of similar size,” he said. Such foams could then be shelf-stable for weeks and months, he added.

Using a technique called ‘in shear emulsification-solvent attrition’, the researchers prepared micro-rods or micro-ampoules which can then be loaded with bioactive compounds. Earlier tests showed that both hydrophobic and hydrophilic silica particles could be loaded, as well as yeast cells and plant pollens.

They have since developed micro-rods that contain liquid compartments, allowing for the incorporation of liquids and oils.

The study, funded by the EPSRC (UK) and Unilever Research Vlaardingen, is published in the journal ChemPhysChem.

One possible application is in ice cream, said Dr Paunov. “One could structure the foam using these products and put in fish oil as a food additive. We can mask the smell with the shellac or fibres of mixed composition,” he said.

However, the food applications go way beyond just ice cream, he added.

Work in progress

The ongoing work in the Surfactant and Colloid Group at Hull University is focussed on clarifying how the variables, including the type of wall material, the type and amount of oil, and other factors, affect the encapsulation efficiency and foam-stabilisation capacity.

“By using other encapsulation materials, such as enteric polymeric materials, pH-sensitive micro-ampules could be made,” they wrote in ChemPhysChem.

“Creation of composite capsules using two or more compatible wall materials can be used for additional fine-tuning of the capsule stabilisation and delivery and release properties,” they added.

Dr Paunov told FoodNavigator that the one-step process can be modified to incorporate pH sensitive polymers to encapsulate and control the release of edible oils. “The idea is to control the release of the oil in the stomach or in the lower intestine.” he said.

 

“There are lots of parameters we can play with,” he said, before adding that the micro-rods are “quite easy to produce. You don’t need any high-tech equipment.”

 

And the Hull group is not looking only at foods – the micro-rods also have potential for the controlled release of pharmaceuticals or for stabilisation of foams in the cosmetics industries, he said.

Source: ChemPhysChem
Volume 10, Issue 15, Pages: 2599-2602
“Novel Multifunctional Micro-Ampoules for Structuring and Encapsulation”
Authors: A.L. Campbell, S.D. Stoyanov, V.N. Paunov

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