Milk Powder & Infant Formula

Milk Powder Categories

The Milk Powder Manufacturing Process

1. Milk reception and standardisation

Raw milk is received, tested for composition and microbiology, then standardised by separation and blending. For WMP this means adjusting fat content; for SMP, removing essentially all fat. For infant formula, the base milk is typically skimmed and then fortified with selected oils, lactose, vitamins, minerals, etc. according to the recipe.

2. Pasteurisation

HTST pasteurisation at 72°C/15s or higher. Some powders use higher pre-heat treatment (90–95°C for 30s–5min) to denature whey proteins for specific functional properties. See milk pasteurisation.

3. Evaporation

Milk at ~12% solids is concentrated to ~48–50% solids in a multi-effect falling-film evaporator with thermal vapour recompression (TVR) or mechanical vapour recompression (MVR). Typical configurations:

• Multi-effect TVR — 3 to 7 effects; steam consumption ~0.15–0.30 kg steam/kg water evaporated
• MVR + TVR hybrid — lower energy than TVR alone; electric power for compressor
• Pure MVR — highest energy efficiency; ~0.02–0.05 kWh/kg water evaporated

Concentration is limited by viscosity. Above 50% solids, milk viscosity rises sharply, increasing pumping costs and risk of spray dryer blockages. See our evaporator mass and steam balance calculator for sizing.

4. Homogenisation (for WMP and infant formula)

The concentrate is homogenised at 80–100°C and 100–200 bar to reduce fat globule size for stable rehydration. Skip for SMP. See homogenisation.

5. Spray drying

Concentrated milk at 48–50% solids is atomised into a hot air stream (160–220°C inlet, 80–100°C outlet) in a large drying tower. Water evaporates from the droplets in 5–30 seconds, leaving dry powder. Three atomiser types are used:

• Rotary atomiser (wheel) — high speed disc; flexible, common in larger plants
• Pressure nozzle — high pressure through orifice; finer particles
• Two-fluid nozzle — air + liquid mixing; specialty applications

Inlet air temperature drives capacity but is limited by thermal damage. Outlet temperature controls residual moisture. Modern spray dryers integrate a fluidised bed at the base ("integrated fluid bed", "MSD™") for agglomeration and final drying.

6. Agglomeration and lecithination

Premium powders (especially infant formula) are agglomerated to give larger, free-flowing, instantly-soluble particles. This is achieved by partially re-wetting the powder and re-drying in a fluid bed, allowing particles to fuse into larger structures with internal porosity.

For instant whole milk powder, agglomeration is combined with lecithination — spraying a small amount of soy lecithin onto the warm powder surface to make it wet quickly when reconstituted.

7. Cooling, sieving and storage

Powder exits the dryer at ~50–70°C and is cooled to ambient in a fluid bed cooler. It is then sieved (typically 1.6 mm screen) to remove agglomerates and foreign objects, magnets remove ferrous contamination, and the powder is stored in food-grade silos or transferred directly to packaging.

8. Packaging

Bulk powders (WMP, SMP, MPC) go into 25 kg paper-and-poly bags or 750–1,500 kg big bags (FIBC). Retail products go into tin cans (infant formula 400–900 g typically), foil pouches or plastic tubs. Infant formula in particular requires nitrogen flushing or vacuum-pack with desiccant for shelf life and oxidation control.

Infant Formula — The Premium Specialty

Infant formula is the highest-value milk powder category and has the most demanding processing, regulatory and quality requirements:

• Recipe complexity — typically 50+ ingredients including specific vegetable oils (palm, coconut, soy, sunflower), demineralised whey, lactose, protein concentrates, vitamins, minerals, nucleotides, probiotics, prebiotics, DHA/ARA oils, taurine, choline, etc.
• Composition tolerance — typically ±5–10% of label values on key nutrients, with regulatory minimums and maximums
• Microbiological standards — Cronobacter sakazakii and Salmonella absence; rigorous environmental monitoring
• Traceability — full batch traceability from raw materials to retail can
• Regulatory complexity — Codex CXS 72-1981 baseline; EU 2016/127 and 2016/128 for Stage 1, 2, 3, GUM, FSMP; China GB 10765/10766/10767; FDA infant formula rules; export country-specific requirements
• Brand protection — counterfeit risk is high; traceability and authentication features required

See our infant formula consultancy page for the commercial services offering.

Energy and Cost

Milk powder manufacturing is energy-intensive. Approximate energy consumption per kg powder:

For a 1,000 kg/h infant formula plant: ~2 MW of total energy consumption. Energy is one of the top three operating costs alongside ingredients and labour. Energy-efficient evaporator design (MVR over TVR) and heat recovery on spray dryers can deliver 20–40% energy savings.

Key Quality Parameters

Common Defects and Their Causes

Frequently Asked Questions

What is the difference between WMP and SMP?

WMP (Whole Milk Powder) contains ~26% milk fat and is made from whole milk. SMP (Skimmed Milk Powder) contains less than 1.5% fat and is made from skimmed milk. WMP is more expensive per kg, has different functional properties, and shorter shelf life due to fat oxidation. SMP is the workhorse commodity ingredient with 12-24 month shelf life.

What is the spray drying process?

Spray drying atomises a concentrated liquid (typically milk at 48–50% solids after evaporation) into a hot air stream at 160–220°C. Water evaporates from each droplet in 5–30 seconds, leaving dry powder. The process produces uniform spherical particles with a narrow size distribution and minimal heat damage when properly controlled.

How is infant formula different from regular milk powder?

Infant formula is a fully-formulated nutritional product designed to mimic breast milk, with typically 50+ ingredients including specific protein sources, fats (vegetable oils mimicking the fatty acid profile of breast milk), carbohydrates (lactose), vitamins, minerals, nucleotides, prebiotics, DHA/ARA. It has extremely stringent microbiological standards (notably Cronobacter sakazakii absence) and regulatory compliance requirements (EU, FDA, Codex, China GB).

What does WPNI mean?

Whey Protein Nitrogen Index — a measure of the residual undenatured whey protein in milk powder, used to indicate heat treatment intensity. Low-heat powder (WPNI >6.0 mg/g) has minimal protein damage and is best for cheese-making applications. High-heat powder (WPNI <5.0) is used for bakery and yogurt where the denatured whey proteins are functional.

Why is milk evaporated before spray drying?

Spray drying is energy-intensive — about 10x the energy per kg water removed compared to evaporation. So milk is first concentrated from ~12% solids to ~50% solids in a multi-effect evaporator (much cheaper energy per kg water), and only the final 50% is removed by spray drying. The 50% concentration is a balance between economics and viscosity (above 50%, viscosity rises sharply).

What is agglomeration in milk powder production?

Agglomeration is the process of fusing small powder particles into larger, porous structures that wet and disperse quickly when reconstituted. It is done by partially re-wetting the powder in a fluid bed and re-drying. Combined with lecithination (soy lecithin spray) it produces "instant" milk powder that dissolves easily without lumps.

What is the Cronobacter sakazakii risk in infant formula?

Cronobacter sakazakii is a Gram-negative bacterium that can cause serious illness in newborns and immunocompromised infants. It can survive in dry environments and infant formula has been a documented source of outbreaks. Infant formula plants implement extensive environmental monitoring, dry-cleaning regimes, and zoning controls (zone 1 high-care areas) to control this pathogen. Codex and EU regulations require absence in 1.5 kg samples.

Further reading: John Watson publishes articles on dairy industry topics on LinkedIn. Browse all articles by John Watson on LinkedIn →

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