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Amorphous Lactose in Food

ProUmid Application Note

Ingredients, such as sugars, can be present in an amorphous or a crystalline state. The amorphous state is often caused process-related, e.g. during spray- and freeze drying, grinding, compaction, extrusion, evaporation or baking.

In general, amorphous products are hygroscopic. The associated high water-binding capacity favors uncontrolled crystallization if a critical moisture content is exceeded. In consequence, product changes such as caking, reduced solubility, increase of Maillard reactions and fat oxidation as well as a rougher mouthfeel affect the physical and chemical stability, the acceptance, and the quality of the product.

Application Note

In this context, milk-based powders are often critical, as a certain amount of amorphous lactose often develops during manufacturing. Due to the versatile use of lactose-, milk- and whey powder this is important in both the food- and pharmaceutical sectors.

To estimate the stability of such products and formulations the determination of the amorphous fraction and their crystallization kinetics is crucial.

The DVS method is based on the higher moisture sorption affinity of amorphous compared to crystalline materials. In addition, water vapor sorption induces crystallization of the amorphous parts. Both kinetics of water vapor sorption and crystallization events can be followed by DVS experiments.