Droogfase

Droogfase (Dutch for drying phase) is a term used in Dutch technical literature to describe the stage in a process during which moisture is removed from a material until a specified dryness is reached. The dryness target is expressed as moisture content or water activity and varies by material and purpose. The term is widely applied in food processing, agriculture, construction, and materials engineering, and is often distinguished from earlier humid stages of processing.

In food processing and preservation, the droogfase follows initial preparation and pre-drying steps. Its goal is to reduce moisture to levels that inhibit microbial growth and spoilage and to improve texture, color, and shelf life. Common methods include sun drying, hot-air drying, tray dryers, freeze-drying, and microwave or infrared drying. Process parameters such as temperature, airflow, humidity, and product geometry determine the drying rate and final moisture content.

In construction and wood technology, the droogfase refers to reducing moisture content in materials such as timber and concrete composites. Proper drying prevents warping, cracking and fungal growth. Wood seasoning, for example, uses controlled airflow and temperature to reduce moisture from kiln-shed values to equilibrium moisture content for the local climate.

In pharmaceutical, chemical, and materials engineering, the droogfase describes removal of solvents and residual moisture from powders, gels, ceramics and films. Drying kinetics are described by models that predict constant-rate and falling-rate periods, influenced by temperature, humidity, and material diffusivity. Moisture content and water activity are used to assess completion.

Related topics include dehydration, drying curves, and moisture content.