Dairy powders consist of many different product sources. Basic dairy powders include WMP (Whole Milk Powder), SMP (Skim Milk Powder), MPC (Milk Protein Concentrate), whey powder, WPC (Whey Protein Concentrate), butter milk powder etc. Whey and WPC (Whey Protein Concentrate) powders are derived from the whey by-product in cheese manufacturing. WMP is manufactured by concentrating and drying whole milk. These powders are high in fat and protein. SMP is the product of concentrating and drying skim milk. The milk is skimmed to take the cream off, generally for butter manufacturing or other cream based products. These powders are low in fat and high in protein. MPC is produced from skim milk with the protein concentrated, typically by membrane filtration. Whey and WPC by-products from cheese making are concentrated and dried.
WPC has the protein concentrated by membrane filtration. Basically the valued constituents, specifically protein, are recovered from process by product streams and used in other food/dairy manufacturing. In order to economically ship these products, and to extend the shelf life, the water is removed. Typically water above 4% in a dried product significantly reduces the shelf life. So, the goal is to dry the product to the specified target but not too dry because of costs: loss in revenue due to volume/weight and the cost of energy for drying.
The control of the target moisture is the most important parameter in the analysis of dairy powders. Other constituents of interest include protein, fat and lactose. Lactose may also be removed by membrane filtration. Analysis of concentrated whey samples can also be used to optimize the drying conditions.
Since the products that need to be dried consist mainly of water, the water must be reduced before drying. Evaporators have been used to remove most of the water by heat. More recently, the water is being removed by membrane filtration. This technique uses much less energy to remove the water. The concentrated product is then fed to a dryer and sprayed into a heated air flume. This heated air removes the moisture to a much lower level (<4%) to produce a powder.
NIR analysis has been long used for the analysis of dairy powders and in-process materials. NIR has the ability to analyze all of the incoming, in-process and final products in dairy powder production for protein, fat, moisture and more in 30 seconds. Accurate, timely data will help to optimize the milk powder production and increase profits.