Fat filled milk powders are a range of skimmed milk powders that are enriched with vegetable fat before dehydration.
Fat filled milk powder is obtained by blending high quality skimmed milk powder with vegetable fat. Powder is atomised (spray drying) in order to easily reconstitute the product.
Fat filled milk powder is a total or partial whole milk substitute. This substitute has the same physical, chemical and organoleptical properties as a dairy product. It helps reducing formulation costs for a product without any impact on its quality.
In fat filled milk powders, proteins come indeed from non-fat milk solids, whereas fat is of vegetable origin.
The choice of fat used in the mix is crucial and must be as close as possible to the dairy fat that it is replacing. Most of the time, the vegetable fats that are used are palm oil, coconut oil or copra oil, in quantities varying from 26-28% (most common) to 50%.
Proteins used to manufacture fat filled milk powders must be of the highest quality, must dissolve easily and totally, must be stable in order not to bring any unpleasant taste to the finished product and must be a good source of essential amino acids. Protein content varies according to the expected use.
Whenever fat filled milk powders are used to reconstitute milk in beverages, low protein fat filled milk powders are more usually used. On the contrary, for yoghurts or curd and whenever a fermentation must occur, high protein fat filled milk powders will be used (a protein content of 24% for instance).
Usually vitamins, minerals and emulsifier (lecithin-like) or stabilising agent are added to the product.
The right treatments give the product a good wettability and solubility.
A stabilising agent in fat filled milk powders helps improve the product viscosity thanks to its action with the proteins that it maintains in suspension, and improve the product stability during freezing and unfreezing processes.
The emulsifier agent improves fat dispersion in aqueous phase and maintains such emulsion. Emulsifier adds to the homogenisation, but does not substitute for it. Choice of emulsifier is important to obtain a product with the right viscosity, that flows easily and that remains stable long enough for its commercialisation. Usually lecithin is chosen. Lecithin is added at the end of the drying process in order to give the powder a maximum of properties: lecithin improves powder wettability (ability to capture water for good hydratation, depends on water affinity) and solubility (ability to dissolve in a liquid), it also allows a stable dispersion after reconstitution. In a nutshell, lecithin helps obtaining a solution and a dispersion faster.
Milk is an important source of vitamins A, D, E, K and many others that contribute to its high nutritional value. Nevertheless, fat-soluble vitamins are not present in skimmed milk (A-vitamin for instance). To address this deficit and to meet the human body demands vitamins may be added.
Calcium, phosphorus and sodium are the main minerals present in milk and often constitute an essential part of the alimentation of children and elderly.
Powder may be treated in order to be « instant ». This treatment improves milk reconstitution: agglomeration forms holes between powder particles as a result water may penetrate easily and rapidly in these holes during reconstitution. Agglomeration process has several steps: hydrating particle surfaces with steam, with water or with a mix of both, drying, cooling and screening to eliminate the finest and the biggest particles. Two methods of agglomeration are used:
- Primary agglomeration that happens directly during spray drying by adding fine powder in the concentrated milk cloud.
- Secondary agglomeration happens by rehydrating an already dried powder.
Such agglomeration is not enough for powder that contains fat. Free fat on the powder surface prevents a good wettability. This is the reason why lecithin is also sprayed into such powder for agglomeration.