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Freeze-Dried-Fruitcom
The field guide to freeze-dried fruit quality, processing, and market trends.
Glossary · Process & science

Water activity (aw)

A measure of how available the water in a food is, reported on a 0–1 scale. Pure water sits near 1.0; freeze-dried fruit typically sits well below 0.3. Water activity predicts microbial and texture stability better than moisture content alone.

Related terms in Process & science

Moisture content The percentage of a product's weight that is water. Sublimation The phase transition from solid directly to vapor without passing through liquid. Lyophilization The technical name for freeze-drying. Primary drying The first and longest phase of a freeze-drying cycle. Secondary drying The final phase of a freeze-drying cycle. Eutectic point The temperature below which a solution is fully solid. Cycle endpoint The point at which secondary drying is complete and the product has reached its target moisture and water activity.

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