About Bakery Vacuum Cooling

Cooling is a key step in Bakery production. Take the bread cooling as example, The main objective is to reduce the internal temperature of the baked bread from 93 – 97°C at the time of debonding or baking to 32 – 43°C. This step can make the finished product reach the best preservation quality and meet the statutory humidity limit of 38%.

During the cooling process, due to the difference in water content between bread crumbs (with high water content) and bread crust (with low water content in the external part exposed to the convective cold air flow), the baked bread will lose water and become dry.

The temperature gradient between the product core (higher temperature) and the cooling environment (lower temperature) causes the product to dissipate heat to the surrounding environment. This gradient reaches its maximum at the end of baking and the beginning of cooling, but it decreases to zero as it cools down.

From the molecular point of view, cooling will cause the partial retrogradation of amylose of starch, that is, almost complete recrystallization, to form the bread crumb structure. This change is the key. It makes the bread slicing operation possible, which is the result of bread firmness and shaping, and will not collapse under the mechanical action of the cutter.

Bakery Foods Vacuum Cooling

Vacuum cooling is a relatively new technology, which can reduce the difference between ambient atmospheric pressure and water vapor pressure. The vacuum system uses a pump to remove gas and water vapor from the cooling chamber, thus forming a partial vacuum or extremely low pressure zone. This will accelerate the evaporation of free water in the product.

Vacuum cooling is a fast cooling method, which is applicable to unstable products that are easy to collapse when cooling. Vacuum cooling enables bakeries to avoid dependence on the main atmospheric conditions and always achieve consistent results and uniform cooling. The equipment required for this purpose must be isolated and sealed from the surrounding area and may be of the batch or tunnel type.The beneficial of vacuum cooling for bakery foods comparing with tradition cooling:

  • Shorten cooling time (from 100°C to 30°C only takes 3 to 6 minutes).
  • Reduce the risk of bacteria contamination after baking, and extend shelf life
  • Compact design,The product can be cooled in 20 m2 equipment instead of 250 m2 cooling tower
  • Less weight loss because cooling is only carried out by evaporation
  • Shorten the baking time or reduce the energy consumption in the baking process
  • Greatly reduced shrinkage of the product, the appearance and symmetry of the shell are better
  • The product remains tough to reduce the chance of collapse during slicing