What is the Optimal Moisture Content and Water Activity?
The moisture content of properly cured cannabis flowers should be below 13%. Within the food industry, water activity below 0.60 aw is considered to be shelf-stable without refrigeration. Products between 0.60-0.85 aw will not require refrigeration but will have a limited shelf-life. Any products above 0.85 will require refrigeration or other way to prevent microbial growth.

Even the smallest amount of water in or on a product can lead to dangerous microbial growth (like bacteria, yeast, and mold) and a spoiled batch of products. Higher moisture content means that products are more susceptible to microbial growth, so testing the moisture content will reveal the probability of any growth occurring (called microbial viability), which ultimately tells us the shelf-life and safety of a given flower or product. Alternative to high moisture content, moisture content that is too low can negatively alter the properties of your products as well, such as how they taste or their texture. It’s important to understand this ratio and where your products fall on the spectrum (see note below).

Water activity measures how microbes will react to any water that exists in your flower or product. Higher water activity indicates higher microbial growth potential, and lower water activity will indicate a lower growth potential, and thus, a longer, more stable shelf-life.

A moisture analyzer is used to calculate the moisture content, while a water activity meter is used to measure water activity.