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Bakery - Glaze
Batter & Crumbs
Biscuit - Barrier
Candy sugar coating
Cereal Coating
Cheese - Anticaking
Cheese - Ferment
Chocolate - Enrobing
Chocolate - Glazing
Doughnut with icing sugar
Dragee - Hard panning
Dragee - Soft panning
Fresh food - Preservation
Nuts - Candied pralines
Nuts - Caramel praline
Nuts - Crunchy coating
Nuts - Dry-roasted
Nuts - Fried & Salted
Pet food coating
Snack coating
Vegetable casing extrusion
Application of a barrier
A layer inside a product which is in contact with another layer may contain a component which may migrate and affect the product quality. To a certain degree, this migration can be prevented. The choice of a barrier ingredient and the application method are critical.


This product can be :
  • A wafer on which a light aerated cream is applied,
  • A biscuit on which an ice-cream is applied ...
In most cases the component whose migration must be prevented is water. Its ability to migrate is measured by water activity. Alternatively, the component is fat e.g. butter.


The ingredient used to form a barrier can be:
  • Fat, generally a saturated fat which is solid at ambient temperature,
    Chocolate is such a fat, especially if it is partly made of vegetable cocoa equivalent;
  • Protein-based ingredient: zeine, gluten;
    Proteins or other hydrocolloids have a limited barrier effect against moisture and are rather used as a barrier against fat migration.


The barrier must be prepared to be applied:
  • Fat is melted and kept a the adequate temperature;
  • Protein is dispersed in a suspension.
The coating operation consists in applying the required quantity in an homogeneous way.
It is usually a continuous or semi-continuous operation in the industry.
After coating, the applied ingredient must be stabilised by cooling or drying depending on its nature.

Coating system

The application system may consists in an enrobing machine or better a spaying machine if only a topical application is desired.

Key features

The process displays critical factors to control:
  • Temperature;
  • Application pattern i.e. homogeneous;
  • Dosage, too little the barrier is not effective, too large it may leave a unpleasant taste;
  • Precision, to avoid pollution of the immediate environment.
The biscuit material is sensitive to moisture of topical ingredient.
Although simple, the coating process needs a close control of the application of a minute quantity of the barrier.
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