Evaporation in baby food
The basic composition of any infant formula consists of:
The proportion, the quality and the processing of these elements determine the overall quality of the food.
Production of Infant Formula/Baby Food mix
Dried infant formula can be produced using either a ‘dry mix’ or a ‘wet mix’ process. Each process has its specific advantages and disadvantages. Of the two processes, the wet mix is more commonly used.
The main advantages of ‘dry mix’ is that the absence of water during the process should make the product safer from a microbiological point of view, as no growth can be expected and that production and operating costs are lower compared to the wet process. The disadvantages of ‘dry mix’ include the fact that production does not allow the addition of lipids, which means that the ingredients should already contain them. Plus as no heat treatment is included during ‘dry mix’, physical and microbiological quality is determined by the quality of the raw materials used, and how the actual dry mixing is performed. Since the different ingredients have different densities, they can segregate during canning and transportation and the final the product can have an inhomogeneous appearance and composition, which can be vital for the end-user.
In the ‘wet mix’ process the situation is different. All quality aspects during wet mixing, concentration by evaporation and spray drying can be controlled to a higher degree resulting in better quality of the powder in terms of microbiology, physical and chemical properties. The disadvantage is the higher capital and production costs of this process. The ‘wet mix’ process is, however, the most widely used, sometimes combined by adding some of the dry nutrients (e.g. vitamins, trace elements or carbohydrates) after the drying process, and each one of the major producers has their own way of preparing the 'wet mix' before final evaporation and/or drying (a typical process flowsheet is shown below)
Figure: Infant formula baby food process flow sheet Source: http://www.spx.com/en/apv/industries/dairy/evaporated-dried/baby-food/
It is an accepted fact that it is cheaper to remove water in an evaporator than in a spray dyer. The raw materials used in the different infant formulations are often recombined to a lower solid content than can be dried. This is because the powdered materials dissolve better at lower solids content.
An evaporator working as a one-stage finisher is therefore used to concentrate the premix before the final drying stage. This has the following advantages:
- economy, due to higher solids content
- it is possible to pasteurize the premix to a higher temperature without viscosity problems
- the concentrate is de-aereated resulting in a powder with lower content of occluded air
- the high-concentrator will work as feed system for the spray dryer - the product is therefore not exposed to any contamination risk
Figure: Falling film evaporator with thermal vapour recompression Source: Tetrapak
Equipment: typically falling-film tube or plate evaporators supplied with either thermal vapour recompression (TVR) or mechanical vapour recompression (MVR). Starting solids content typically 30-40%
Final solids content (after evaporation) varies from 45-60% depending on the manufacturing method and ingredients used.
Typical temperatures: 63-77 °C (145-170°F)