The palatability of a backed product is enhanced by a glaze which gives it a shine reflecting the light. The application must be as even and complete as possible while restricted to the product itself and not smearing the plate or mesh supporting it. Methods for an accurate dosage and application pattern exist.
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Base
There is a very wide range of baked product which can be glazed : doughnut, croissant, bun, bread ...
Ingredients
The glazing ingredient may differ depending on the product but can be classified into main categories :
Light glaze provided by milk, milk protein, soy protein, egg;
Medium glaze with a glucose syrup;
Heavy glaze provided by:
A sugar fondant,
Chocolate, in this case the operation refers as enrobing rather than just glazing.
Process
The glaze must be prepared ant its preparation can be thoroughly different according:
Light glaze : dispersion or dilution of a protein-rich powder or of a concentrated slurry into a lighter suspension,
The preparation must be kept cold to prevent microbial growth;
Medium glaze : dilution and heating of a concentrated glucose syrup,
The preparation must be kept hot to keep the viscosity low and allow the application;
Sugar fondant : the preparation involves dispersion of fine sugar in a concentrated sugar solution,
The preparation must be kept at constant temperature and agitation to maintain its physical properties - whiteness, viscosity and crunch - resulting from the balance between dissolved and finely crystallized sugar;
Chocolate : the solid chocolate must undergo a complex operation called tempering : melting, cooling, partiel re-melting,
The preparation involves a complex system which ensures melting, agitation, circulation and temperature control before use.
The coating operation consist in applying the glaze on the product while avoiding losses on the immediate surrounding:
The product enters the coating zone;
The coating is applied - see the next heading,
Losses are recovered or cleaned;
The coating is stabilised by either adequate way:
Baking,
Drying,
Cooling;
It is a continuous operation in most cases.
Coating system
Different coating systems can be used:
Spraying for accurate application of a low viscosity liquid;
Curtain and recovery/recycling of excess in the case of the thick application of a viscous fluid;
The difference between the systems lie in the engineering details designed to cope with constraints : cooling/heating, recycling, cleanliness and cleanability.
Key
The process displays critical factors to control:
Ingredient composition - concentration, solid particles - in the way it influences its physical behaviour;
Viscosity control by temperature control;
Precision of application : dosage and targeting;
Hygiene as the product itself or the production environment offer ideal conditions for a microbial growth.
Among the glazed products, the croissant is a star.
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