Saturday, September 07, 2019

Evaporated milk processing

Evaporated milk is milk concentrated to one-half or less its original bulk by evaporation under high pressures and temperatures, and usually contains a specified amount of milk fat and solids. Evaporated milk is not sweetened; it is sterilized in cans.

The milk is piped through filters and into the pasteurizers. Here, the milk is quickly heated in one of two ways. The High Temperature Short Time method (HTST) subjects the milk to temperatures of 161 °F (71.6°C) for 15 seconds. The Ultra High Temperature (UHT) method heats the milk to 280°F (138°C) for two seconds.

Evaporation in the dairy industry is boiling off water from the solution. The milk is then evaporated to a specific dry solid concentration. The basic principle involved in operation of an evaporator is heating the milk to a temperature slightly above its boiling point corresponding to the vacuum in the evaporation chamber and separating water vapors from the concentrated mass, simultaneously condensing the vapors in a condenser.

The total dissolved solid concentration achieved in evaporation is critical as it affects the performance of subsequent operations and the quality of the final product. Converting milk into evaporated milk essentially entails reducing the volume of the milk by evaporation and subjecting the concentrate to a sterilizing heat treatment, usually in‐can.

The products to be evaporated are normally heat sensitive and can be destroyed by adding heat. To reduce this heat impact, evaporation takes place under vacuum, sometimes at temperatures the shortest possible residence time.

After evaporation, the milk is homogenized. Homogenization reduces the mean size of the fat globules so that they are distributed uniformly in the milk and do not rise to the top creating a creamy layer.
Evaporated milk processing

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