Water Activity
Water Activity (Aw) measures the availability of free water in coffee beans, indicating their ability to absorb moisture and react with external factors. This value ranges from 0.0 to 1.0, with 1.0 representing pure water. When Aw is low, bacteria and mold struggle to grow, preserving the coffee’s flavor and extending its shelf life.
Conversely, if the Aw level is too high, microbial growth accelerates, negatively impacting the quality and longevity of the coffee. While Aw is related to moisture content, the two are not identical—coffee with 10-12% moisture content typically has an Aw below 0.6. If this threshold is exceeded, oxidation speeds up, leading to the loss of key aromatic compounds.
The ideal Aw range for coffee storage is between 0.45 and 0.55, which helps prevent microbial contamination. Proper control of Aw through moisture-resistant packaging, dry storage conditions, and regular monitoring is crucial for maintaining product quality.