Transforming liquid milk into dry powder requires removal of almost all the water, the amount of which exceeds by many times that of the final product. During this water removal process, significant changes of the properties, physical structure and appearance take place. Milk is a sensitive product and its quality can be seriously affected especially by the influence of heat or bacterial activity. Thus it is obvious that a single water removing process cannot have optimum performance throughout the whole duration of dehydration.

Evaporation is a process by which a liquid is brought to its boiling point by external heating thereby transforming the water into vapour, which escapes from the surface of the liquid. The rate of evaporation depends primarily:...

Spray drying is an industrial process for dehydration of a liquid feed containing dissolved and/or dispersed solids, by transforming that liquid into a spray of small droplets and exposing these droplets to a flow of hot air. The very large surface area of the spray droplets causes evaporation of the water to take place very quickly, converting the droplets into dry powder particles...

The main components of a modern spray dryer, powder handling and storage as shown in Fig. 4.1. are:

Drying chamber
Hot air supply system
- Supply fan...

The capability of spray drying installations is determined by the type of chamber and by the type and combination of the components incorporated. Any modern spray drying installation must have the components as given in chapter 4. What makes the difference between various installations as to their ability to fulfil the qualitative and economical requirements...

Industrial production requires a daily check of the plant capacity, product output yield, consumption of energy etc. by collection of various production data and calculations. Examples of some useful technical calculations are given in the following sections...

After erection of a new spray drying installation it has to be brought into operation. This phase is called commissioning and proceeds in several stages:

1.Mechanical test of all individual components,
2.Test and...

There are a great number of products manufactured in the milk powder industry including milk powders, modified milk powders, powdered milk by-products, and dried milk based products containing either milk solids only or also other foodstuff components. Therefore milk powder technology is a broad subject. The target of industrial production is to produce products which fulfil all the qualitative requirements...

A great number of operational parameters and conditions influence the performance of a spray drying plant. One essential factor is the quality of the processed milk, evaluated not only according to general quality standards, but also composition and physical-chemical properties as influenced by the composition itself...

About 40 years ago milk powder quality was evaluated using the same criteria as for liquid milk products. The aim of such evaluation was:

a) to ensure that the final product met the specified composition i.e. fat content, total solids content and possibly content of other ingredients, if any (sugar etc.).
b) To ensure that...

Analytical methods for dry milk products are an almost forgotten subject in the literature. The only existing publication was issued by GEA in 1978 [31], but updated versions of analytical methods can now be found on GEA's Analytical Methods for Dry Milk Products page.

Since the time of the first publication, many new methods, especially for testing instant properties, have...

The expression troubleshooting may sound quite dramatic. However, what is understood here as troubleshooting is in fact any intervention that changes the operational parameters in order to obtain the desired result. An operator of a spray dryer is exposed every day to situations where he has to decide what to do if, for instance, the final moisture content of the product is suddenly too high...

Available in the PDF