The release of aromatic substances in the mouth

The product composition is in fact simply the starting point. A dynamic aspect, namely what happens with the product when it is in the mouth, is then introduced as a secondary issue.

Processes that are of influence on the concentration of the flavouring in the air space above the product, the so-called ‘gas phase’ or ‘headspace’, occur during chewing in the mouth. The gas phase is shown in the above diagram by depicting the oil droplets further apart than when in a liquid. How easily the flavouring escapes into the gas phase is of importance when chewing in the mouth. This gas phase goes with the air breathed in to the nose and in this way determines the smell of a product. How the flavouring moves from the solid or liquid phase of the product itself to the gas phase is also called ‘release’ of the flavour. This is a dynamic process that depends on various factors that play a role in the mouth, such as an increase in the temperature, the addition of water (saliva), possible 'flipping' of the emulsion (from water in oil to oil in water) and melting or breaking up of the product.

The acidity (pH) in the mouth also influences the concentration of the flavouring in the headspace. A low pH naturally already in itself gives an acid taste, but can also increase the vapour pressure of a flavouring so that it will be observed more strongly. However, this applies only to flavour components that are themselves acids. In contrast a high pH will actually lower the vapour pressure of an acid flavour component so that the perception of the flavouring will decrease.

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