Processing of Unsweetened Condensed Milk (Evaporated Milk)
What is Unsweetened Condensed Milk?
Unsweetened condensed milk, also known as evaporated milk or dehydrated milk, is a concentrated milk product where approximately 60% of water is removed. Unlike sweetened condensed milk, it contains no added sugar, resulting in a slightly caramelized flavor due to high-heat sterilization (around 240°F).
It offers:
- Longer shelf life
- Higher nutrient and energy density
- Added Vitamin D for improved nutritional value
Unsweetened condensed milk can be made from whole milk, skim milk, or recombined milk using skim milk powder, anhydrous milk fat (AMF), and water.
Manufacturing Process of Unsweetened Condensed Milk
1. Reception and Testing of Raw Milk
Milk is transported in refrigerated tankers from farms to the plant. Upon arrival, it is tested for:
- Odor and taste
- Bacterial content and sediment
- Protein and fat composition
2. Standardization
The fat and solids-not-fat (SNF) content is adjusted to required levels. Typical compositions are:
- Fat: 7.5%–9.0%
- Non-fat milk solids: 18%–22%
3. Preheating / Pasteurization
Milk is preheated to:
- Improve heat stability
- Ensure optimum viscosity
4. Evaporation
Water is removed under vacuum (160–320 hPa) at 55°C–70°C using:
- Multiple-effect evaporators
- Falling film evaporators
- Rising film or circulation evaporators
- Horizontal tube evaporators
(A) Multiple-Effect Evaporator
Utilizes vapor from one vessel to heat the next, maximizing energy efficiency—a key solution in food engineering consulting.
(B) Falling Film Evaporator
Milk flows as a thin film inside vertically oriented tubes, where it boils and partially evaporates. It's efficient and preserves product quality.
5. Homogenization
High-pressure treatment breaks down fat globules to create a stable emulsion, preventing cream separation in the final product.
6. Cooling
The homogenized milk is cooled to around 14°C, preparing it for further processing.
7. Canning
Automatic canning machines fill and seal the product before sterilization.
8. Sterilization
(a) Batch Autoclave:
Cans are placed in crates and sterilized together.
(b) Continuous Autoclave:
Cans pass on a conveyor belt through a controlled sterilization chamber.
Alternative Process Using UHT Technology
For UHT (Ultra High Temperature) Processing, steps 7 and 8 are replaced by:
10. UHT Treatment
Milk is heated to 122°C–140°C for 4 seconds to 2 minutes using a plate heat exchanger, ensuring sterility without damaging nutritional value.
11. Aseptic Filling
Milk is filled into pre-sterilized containers under aseptic conditions, extending shelf life while maintaining safety.
Flow Chart of Unsweetened Condensed Milk Processing
Conclusion
When evaluating a condensed milk product, remember:
- Evaporated milk = Unsweetened condensed milk (no sugar)
- Condensed milk = Sweetened product (contains added sugar)
PMG Engineering, your trusted food industry consultant, offers complete support for setting up dairy processing units, including evaporated milk production systems, aligned with international food safety standards and cost-effective automation solutions.