Description
Dehydration and freeze‑drying are moisture‑removal techniques that lower water activity to inhibit microbial growth.
Technical
Both processes rely on thermal energy: hot‑air dehydration uses evaporation (latent heat of vaporization) while freeze‑drying uses sublimation (latent heat of fusion) under reduced pressure. The removal of water reduces water activity (a_w) below 0.6, suppressing enzymatic activity and microbial proliferation, thereby extending shelf life.
Science
Primary Reaction
Sublimation of ice (solid→vapor) during freeze‑drying; evaporation of liquid water during hot‑air dehydration
Sensory Profile
Aroma ()
dryfruitycaramelizedearthynuttyconcentrated
Origin & History
Civilization
NASA (freeze‑drying), Mediterranean peoples (sun‑drying), industrial sector (hot‑air dehydration)