Double layer microencapsulation may aid flavour retention

By Nathan Gray

- Last updated on GMT

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Modifying the permeability and stability of spray dried emulsion droplets by adding additional layers could provide a novel method of improving the retention of volatile flavour compounds in dry powders, according to new research.

The study – published in Food Chemistry, ​reports that a spray dried, two-layered emulsion can increase the retention of volatile flavours compounds compared to a single layer emulsion coating.

The French research team compared a pea protein isolate-pectin complex to a single coating of pea protein isolate alone. They found that the double layer containing pectin improved flavour retention, and added to overall stability.

“The use of two-layered emulsions as a flavour microencapsulation system was able to increase the retention of volatile molecules during spray-drying,”​ said the authors, led by Adem Gharsallaoui from the University of Burgundy, France.

Spray dried flavour

The researchers noted that one of the most common techniques to produce reliable flavours is to create an oil-in-water emulsion that encapsulates the flavour compound – then spray dry the emulsion to produce a powder.

However, the high temperatures required for spray drying can lead to the loss of certain volatile flavour compounds.

The researchers noted that increased retention of such flavour compounds during the spray drying process is reliant on the stability of emulsion droplets, and the ability of the emulsion droplet membrane to protect the encapsulated ingredient and control its release.

The potential for the use of multi layer emulsions in the food industry – to increase stability of an emulsion – has been investigated many times. As such the researchers investigated a multi-layer coating can be used to improve the stability and protection of flavour compounds in pea protein-coated oil droplets.

Study details

The researchers created oil-in-water containing three flavour compounds: ethyl acetate (EA), ethyl butyrate (EB), and ethyl hexanoate (EH). Each flavour was emulsified within a single pea protein isolate emulsion and also as a pea protein-pectin complex double layered emulsion before spray drying.

Gharsallaoui and his team found that the addition of pectin significantly increased flavour retention.

They revealed that in the spray-dried primary emulsions (pea protein) the retention of volatile flavours increased in line with the boiling points of each respective flavour molecule.

However, the authors noted that when pectin was used as an additional oil droplet coating, flavour retention was found to be approximately the same for all three flavours – with the retention level significantly higher than found in any of the primary emulsions.

The researchers suggested that the beta-sheet structure of the emulsion membrane was protected from heat by the presence of pectin – explaining that such a protective effect could help to explain why flavour compounds in oil droplets coated by two-layered interfacial membranes of pea protein and pectin had higher retention during spray-drying.

Source: Food Chemistry
Published online ahead of print, doi: 10.1016/j.foodchem.2011.03.028
“Properties of spray-dried food flavours microencapsulated with two-layered membranes: roles of interfacial interactions and water”
Authors: Gharsallaoui, A., Roudaut, G., Beney, L., Chambin, O., Voilley, A., Saurel, R.

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