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  • Mobile & Stationary Hydraulics
The Liquid Sweetness

Sweetened Condensed Milk (SCM) is a beloved ingredient in countless desserts and beverages worldwide, known for its rich and creamy texture. SCM is produced by evaporating milk and adding sucrose, while Recombined Sweetened Condensed Milk (RSCM) is made by mixing milk solids, water, and other ingredients. These products have a long shelf-life, making them a convenient choice in areas without refrigeration. As producers strive to meet consumer demands for high-quality SCM, understanding key factors such as microbiology, crystallization, and age thickening is essential. By implementing best practices and maintaining a commitment to excellence, producers can provide SCM and RSCM that satisfies both taste and longevity, setting themselves apart in the market.

Shelf-Life and Spoilage Prevention
One of the standout features of SCM is its extended shelf-life. This remarkable durability is a result of the low presence of spoilage organisms within the product. The high concentration of sucrose in SCM creates high osmotic pressure, effectively inhibiting spoilage organisms. To maximize shelf-life, it's essential to ensure that the sucrose content falls within a specific range: above 62.5% to inhibit most spoilage organisms but below 64.5% to prevent sucrose crystallization.

Microbiology Matters
The microbiological quality of SCM hinges on the quality of the raw materials used in production. It is essential to pay close attention to three critical points:

  • Heat treatment of the milk before evaporation.
  • Heat treatment of the SCM mix.
  • The stage of sucrose addition.

Microbiological problems, particularly post-contamination during filling, can lead to spoilage. To  prevent this, state-of-the-art technology, proper filling techniques and hermetic seals are essential.

Crystallization for Texture and Quality
The crystallization of lactose is vital for SCM's texture and mouthfeel. Small lactose crystals (max 10µm long) are preferred to avoid sedimentation and a sandy texture. Achieving this requires precise cooling, seeding with lactose, and maintaining a consistent storage temperature. Fluctuations in storage temperature can lead to larger crystals. Additionally, crystallization of sucrose may occur with high sucrose concentrations and/or low storage temperatures.

Age Thickening: Understanding and Mitigation
Age thickening, characterized by increased viscosity over time, poses a challenge in SCM and other long-shelf-life dairy products. It results from heat-resistant microbial proteases and physicochemical changes in casein. To reduce this, the following is important.

  • Ensure consistently high-quality raw materials.
  • Implement heat treatment at 110°C or higher.
  • Prevent post-contamination of the product.
Process Description

How Sweetened Condensed Milk is made:

  1. Raw materials: The primary raw materials for Sweetened Condensed Milk (SCM) production include standardized milk, sucrose, and lactose whereas Recombined Sweetened Condensed Milk (RSCM) can utilize various preserved milk products, such as skim milk powder, cream powder, and milk protein concentrate. The quality of the raw materials and their thermal stability are essential for the quality of the final product.

  2. Standardization of milk: The milk is standardized to the desired fat content. This step can be carried out with the APV Compomaster integrated into the pasteurization line. Alternatively, standardization can be performed in batches. 

  3. Sucrose addition: The stage at which sucrose is added determines some of the final product qualities. Sucrose can be added either before heat treatment or during evaporation. The addition stage affects the product's thermo-resistance, age thickening, and final qualities.

  4. Heat treatment: Prior to evaporation, the milk or milk/sucrose mix is heat treated in a plate heat exchanger or infusion plant at specific temperatures to destroy bacteria, yeasts, molds, and enzymes and to control the viscosity of the final product. The temperature and holding time influence viscosity and product quality.

  5. Evaporation: Falling film evaporators concentrate the milk or milk/sucrose mix to the desired total solid level. Evaporation is often integrated with heat treatment to ensure low bacteria counts, optimum viscosity, taste, color, and shelf-life.

  6. Vacuum cooling: One of the most significant aspects in ensuring the formation of small crystals is the vacuum cooling process (also known as flash cooling). The mix is subjected to vacuum cooling to promote the formation of small lactose crystals, which contribute to a smooth product. Lactose seeding is performed before crystallization.

  7. Crystallization and storage: The sweetened condensed milk is pumped to a crystallization tank, where it is left to crystallize. Special tanks with agitators and precautions against post-contamination are used. The product can be directly filled or stored.

  8. Can filling: The SCM is filled into sterilized cans, with minimal headspace to prevent contamination. Cans are sealed, washed, labeled, and prepared for distribution.