Most biscuits and cookies you find in the supermarkets are baked in tunnel ovens. It’s a continuous process that turns dough pieces into biscuits. In general, biscuits and cookies are baked through a long tunnel oven with several independently heated and controlled zones. These zones allow for a variety of baking methods. The color and texture of final products can also be controlled. The shortest ovens could be only one zone while longer ovens have 2 or even more zones. However, tunnel ovens with 3-4 zones are the most common configuration.

The tunnel ovens transfer heat to dough pieces via:

• Conduction through heated surface

• Convection through the air

• Radiation from heat source

A series of physicochemical changes are activated by the heat, the doughs pieces are transformed into biscuits with a firm, dry crust. It’s a rather short baking time from about 2.5 to 15 minutes compared to other bakery products. While baking, there are four main changes happening :

1. The density of the product will be reduced drastically to form a flaky structure. The thickness of raw biscuits will get an increase at the same time.

2. The shape of the product will spread or shrink.

3. The moisture level will be reduced to 1-4%.

4. The surface color of the biscuit will change.

The length of the oven determines the production efficiency most while the desired color, structure and moisture content of products act as other factors. Giving a wide range of possibilities, ovens are designed with many control points. Biscuits are conveyed through the oven on a continuous band. While passing through, the band is supported by lots of rolls that are one by one closely in case of the sagging of the band. After baking, the band will return under the oven for cleaning the surface.

The oven is the key to production efficiency as the baking process is a stage that makes or breaks the final product. These are brief introductions about the biscuit baking. I hope you enjoy it. If you find this article interesting, please follow our Facebook ▶https://www.facebook.com/biscuitequipment    We will share more fun things about biscuits both on our website and Facebook.