Application of a shiny glaze on bakery products
The palatability of a backed product is enhanced by a glaze which gives a shine and reflects light. The application must be as even and complete as possible while restricted to the product itself . It should not smear the plate or mesh supporting it. Methods for an accurate dosage and application pattern exist.
There is a very wide range of baked product which can be glazed : croissant, bun, bread …
A light glaze can be provided by different ingredients and a combination of them :
- egg is the traditional glaze medium AKA egg wash
- milk and milk proteins,
- soy and vegetable proteins
- glucose syrup
Heavier glazes are provided by a sugar fondant or a chocolate couverture, in this case the operation refers as enrobing rather than just glazing.
How does it work?
The coating operation consist in applying the glaze on the product while avoiding losses on the immediate surrounding:
A light glaze is a dilution of a protein-rich powder or a concentrated slurry into a lighter suspension, the preparation must be kept cold to prevent microbial growth
For reference, sugar fondant and chocolate couverture are described :
- 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, partial re-melting, the preparation involves a complex system which ensures melting, agitation, circulation and temperature control before use. The operation may be semi-automatic or fully automatic and continuous.
Losses are recovered or cleaned.
Liquid application by brush or spray
Stabilisation by baking
Different coating systems can be used:
- Traditional brush
- Curtain and recovery/recycling of excess in the case of the thick application of a viscous fluid
- Spraying for accurate application of a low viscosity liquid
The difference between the systems lies in the engineering details designed to cope with constraints:
- hygiene and cleanability
In a high-capacity industrial line, spraying proves the most appropriate application system. If well controlled, it ensures a precise application in quantity and surface.
How do you measure your success?
Key quality features
If obviously first visual, the evaluation triggers multiple questions
After completion, the glaze must display a bright shine
The glaze must be evenly applied and should cover the desired surface, the side of the product being the most difficult
The stability should not be affected by further processing steps : cooling, freezing
Key quality parameters
The process displays critical factors to control
Type of glaze, water content
Viscosity and surface tension
Dosage and application precision, resulting also in reduced consumption and improved hygiene