Milk replacer, imitation milk or filled milk is a replacement for whole milk in which the butter fat has been replaced by a cheaper animal or vegetable fat. Milk replacer is used as fodder for calves, chickens, and pigs, or in a refined form it is used as a whole milk substitute for human consumption.
Calf milk replacer
The finished product composition used for animals has no fixed composition. The proportion of each ingredient varies as follows:
| Fat |
15 – 20 % |
| Skim milk solids (MSNF) |
65 – 80 % |
| Dextrose, lactose, possibly whey solids |
0 – 10 % |
| Emulsifying agents *) |
0 – 2 % |
| Flour: |
0 – 7 % |
|
Minerals, vitamins
*) The emulsifying agents include: lecithin, mono-glycerides, sucro-glycerides |
0 - 0.5 % |
| Minerals |
Ca, Na, Mg, Cu,
PO4, Cl, HCO3 |
| Vitamins |
A, D, E, (B, C)
|
| Antibiotics |
Terramycin or aureomycin |
The fat-enriched skim milk powder can be produced in two ways:
- Dry-mixing skim milk powder and fat
- Drying an emulsion of skim milk concentrate and fat
Dry-mixing skim milk powder and fat
The dry-mixing procedure was the original technique. The fat-enriched skim milk powder was produced by spraying fat on to skim milk powder, which was carried out on a conveying belt passing a nozzle used to spray the fat. However, this product did neither have good solubility nor good shelf life.
Since then, another method has been developed by which the fat is sprayed into a chamber to which skim milk powder is carried in an air current. This results in a product in which the globules of fat are covered with skim milk powder particles.
This product is good in many ways, although for some uses its qualities are not high enough because all the fat is present as free fat and the globules of fat are too big. This results in short shelflife as well as indigestion problems for calves.
Drying an emulsion of skim milk concentrate and fat
In this method, a premix is normally produced containing a higher amount of fat (up to 60 % fat of the total solids content) than is desired in the finished fodder mixture. The premix is then mixed with other components according to the end user's requirements.
The raw product should consist of normally treated skim milk and first-class fats. The skim milk is evaporated to 40-45 % solids and heated to 65 °C. The fats are melted and heated to approx. 55 °C. Both vegetable and animal fat can be used. Anti-oxidants (e.g. butyl-hydroxytoluine) may be added to the melted fat. If emulsifying agents are desired, they will have to be added at this stage. The fat is then heated to approx. 65 °C and mixed with the skim milk concentrate in tanks as a batch process or inline as a continuous process. The mixture of fat and skim milk concentrate is then led through a homogenizer and the emulsion is ready to be dried.
The purpose of homogenizing is to disintegrate the fat globules to make them more easily digestible for the animals. The aim for a maximum size of fat globules is 3µ and a minimum of 90 % less than 1µ.
Filled milk powder for human consumption
Production of filled milk powders for human consumption is used more and more. The composition is equal to that of whole milk powder, i.e. with 26-28 % fat. Various vegetable oils are used and the production is usually based on a mixture giving a melting characteristic equal to butter fat. Various vitamins are naturally added (mainly A, D, and E).
The mixing of the skim milk powder, water, vitamins, and oil is carried out in a vacuum mixer. The drying is done in a plant with fines return for agglomeration and lecithin dosing equipment in order to make the powder cold water instant. The powder is mainly used in large institutions such as canteens, hotels, hospitals, in the army, etc. but in some countries it is also sold in retail packages for direct use in households.
This type of powder is manufactured in countries with limited local milk production. The powder is based on imported skim milk powder, which is reconstituted and mixed with locally produced fat.