Milk powder is widely used as the basis for powdered infant foods and as a raw ingredient in the baking & confection industries. In food-scarce regions or those hit by famine, milk powder is an important source of protein and calories which does not require refrigeration. Transportation charges are significantly lower for milk powder than for bulk whole milk for an equivalent nutritional value, and milk powder has greater shelf life.
Shelf life is, in part, a function of free moisture. Free moisture promotes mold growth in foods: the higher the relative humidity the greater the potential for molding, particularly over 65%RH. However, most desiccated foods have a tendency to absorb moisture from the atmosphere. In a closed container, these food stuffs can therefore have self-desiccating qualities to some degree. Sugar and table salt are two examples of foods with strong desiccating qualities. They are therefore often used as preservatives for other foods which are less desiccating. Milk powder also exhibits some self-desiccating properties which contribute to its long self-life.
The moisture sorption quality of a foodstuff is essential information when it comes to considering packaging and storage conditions. Moisture sorption can also affect texture, color and flow ability of powders.
Which Instrument is Used?
The moisture sorption behavior of foods is quickly and conveniently measured by dynamic gravimetric water vapor sorption, often referred to simply as DVS. The Aquadyne DVS1 and Aquadyne DVS2-HT are both capable of measuring the water content, water uptake, and rates of water uptake.
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This information has been sourced, reviewed and adapted from materials provided by Quantachrome Instruments.
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