Measuring the moisture content in powdered milk is an important quality control step. The Canadian Dairy Commission, for example, states that with low moisture content, chemical reactions in skim milk powder stored at room temperature take place so slowly that the nutritive value is not affected, even after years of storage. A variation is powdered filled milk that Wikipedia describes as filled milk when it is any milk, cream, or skim milk that has been reconstituted with fats, usually vegetable oils, from sources other than dairy cows.
Checking Moisture Content for Powdered Milk
According to the Canadian Dairy Commission target moisture content is 3- 4%. Spray drying is the principal method used for drying milk in the dairy industry. As explained in a Food Product Design article spray drying in its simplest form consists of atomizing the feed, spray-air contact, drying, and separation of the dried product from the drying air.
Because dry powdered milk can absorb moisture from the environment under ambient conditions a quality control procedure could include using a benchtop moisture analyzer to periodically confirm moisture content after the spray drying process and/or just prior to packaging. The IL-50.001 moisture analyzer available from Tovatech is a recommended choice to perform this important task.
The lightweight, portable IL-50.001 moisture balance operates on the thermogravimetric principle, or loss of weight on drying (LOD). Simply explained the change in weight before and after the process indicates the moisture content of the sample when exposed to the unit’s halogen heater, which is coupled with a high-resolution balance. It provides resolution/readout of 0.001g (0.01% moisture), operates in the standard drying mode, and automatically shuts off when the loss of weight is <1mg in 60 seconds. The unit can also be set to shut off at a specified time. It is shipped with an instruction manual and calibration weight.
A Moisture Analysis for Powdered Milk
Here’s a representative exercise for conducting a moisture check on powered milk. Quality control personnel should be guided by their industry or professional association recommendations.
Program the IL-50.001 moisture balance to operate at 105⁰C.
Place the sample pan on the sample pan holder and tare it. Then using a spatula carefully and thinly spread 2 g of powdered milk on the sample pan. Close the lid and press the on/off key.
Moisture analysis will start and the unit will beep when the rate of weight loss is <1 mg in 60 seconds. Percent moisture, percent solids, time and temperature are shown on the backlit liquid crystal display. Transfer data to a computer or printer via the RS 232 interface for record keeping.
A description of moisture analyzer operation is presented in our post on setting up a moisture analyzer.
For answers to questions on the IL-50.001 moisture analyzer or for help in selecting the right equipment for your needs contact the Tovatech scientists.