Milk Powder - Spray or Freeze Dried

Spray Drying

Making powder is a way to preserve surplus milk into storable nutritious proteins.

Skim milk powder can have a shelf life of up to three years. — Full cream milk powder has a shelf life of up to six months because the fat in the powder oxidizes and affect the taste after a certain period.

Spray drying takes normally place in exceptionally large plants as the cost in small scale units is far too high and makes it impossible to sell on the world market.  For small scale plants, you really need to have a unique product with milk from an incredibly special animal if it shall pay off – A Unicorn or something like that.

Milk powder is used in many food productions, e.g.  In the Ice Cream Industry, the Bakery Industry, The Chocolate Industry and a lot of other Food Industries for increasing the protein content

Most important. Substitute for mothers’ milk in Baby foods.

Illustration from Alfa Laval Dairy Handbook

Freeze Drying

Freeze Drying is a conservation process whereby the deep-frozen products water content is removed by temperatures below 0°C and under extremely low pressure.

This process makes that the ice crystals sublimates, i.e. it evaporates without passing through the water phase.  The system can be explained in 3 points

  • The product must be solidly frozen below its eutectic point
  • The system must be capable of evacuation to low pressure
  • A controlled source of heat input to the product must be employed to drive the water vapour from the solid to the vapour state

Because only the water evaporates whilst the product remaining frozen, or at low temperature, the product remains all its nutrients, flavours, and colours – not obtainable with other drying methods

Keeping the Freeze-Dried production in airtight containers gives an awfully long shelf life and no refrigeration is needed.

Related to the dairy industry, freeze drying is widely used to produce all kind of Starter Cultures.

As with Spray Drying, Freeze Drying is a costly way to preserve food so only look for valuable products to be treated this way

Do you want to make powder -- Mejeriet can provide you with the components to set up an efficient production line

Based on the numbered step stone below. Mejeriet shall be pleased to quote you the equipment you need.

Spray or Freeze Drying

10.00 — Pre-treatment of milk — Dry-matter goes from 10% to 45-55% before feeding the Atomizer or the Freeze trays. This can take place in a falling film evaporator, or a UF Unit.

10.01– Spray tower with Atomizer in the top makes the milk in very fine droplets — a calorifair blowing hot air into the Spray tower, evaporating the moister from the fine droplets — Now it’s powder.

10.02 — Freeze-drying is a different approach as the product is solidly frozen while it’s drying under high vacuum

10.03 — Final drying & Instantising so powder is easy to dissolve, can take place in a Fluid-bed as well as other systems, please ask.

10.04 — Packaging equipment for powder.

Note

Both systems are expensive to purchase and operate

 

Illustration from Alfa Laval Dairy Handbook

Above is a illustration of a Fluid-bed where powder can be after-treated in different ways