Evaporated milk is made by removing about 60% of the water from fresh milk, then heat-sterilizing the resulting concentrated milk. No sugar or other preservatives are added during this process.
The Evaporation Process:
The key to making evaporated milk is the process of evaporation, which thickens the milk without burning it. Here's a breakdown:
- Fresh Milk Intake: The process starts with fresh, high-quality milk.
- Preheating: The milk is preheated to stabilize the proteins and prevent coagulation during the evaporation process.
- Evaporation: The preheated milk is then fed into evaporators. These are typically vacuum evaporators that allow the water to boil off at lower temperatures (around 40-80°C or 104-176°F) to minimize heat damage and preserve the milk's quality. This lower temperature is achieved by reducing the pressure inside the evaporator. The removed water is condensed and discarded. This stage concentrates the milk solids.
- Homogenization (Optional): Some manufacturers homogenize the evaporated milk at this stage to further stabilize the fat emulsion and prevent creaming during storage.
- Stabilization: Additives like disodium phosphate or carrageenan may be added in small quantities to prevent age-thickening of the product.
- Cooling: The concentrated milk is cooled down before packaging.
- Canning and Sealing: The concentrated milk is then filled into cans or other sterilizable containers and sealed.
- Sterilization: The sealed cans are then heat-sterilized in retorts at high temperatures (typically 118–122 °C or 244-252°F) for a specific time to kill any remaining microorganisms and ensure a long shelf life. This heat treatment contributes to the characteristic cooked flavor of evaporated milk.
Why No Sugar or Preservatives?
Unlike sweetened condensed milk, evaporated milk relies on the evaporation process and subsequent sterilization to achieve its long shelf life. The removal of water reduces the water activity, inhibiting microbial growth. The heat sterilization further eliminates any remaining bacteria and inactivates enzymes, ensuring the milk remains safe and stable for an extended period without the need for added sugar or preservatives.
Alternatives to Cans
While canning is the traditional method, evaporated milk can also be packed in other sterilizable containers that are airtight and capable of withstanding the high temperatures of sterilization.
