Water Activity & Moisture
Water is the building blocks of life, as most everyone knows, but the life cycle of water on a cannabis plant is often a mystery.
Water can take multiple forms including free water, absorbed water, and bound water. Water testing, in general, is often misunderstood.
What scientists need to understand about water, when it relates to Cannabis, is that the free water is the water that is used by microorganisms to support their growth. The term water activity describes the amount of water available for the hydration of materials. The materials may include plant, food, edible, tablet, or anything that has a surface. If the water activity is too high then microbial growth is more likely.
All cannabis flower and products contain water, but if the water activity is too high, then microbial growth is more likely.
Water activity testing can help determine if a plant’s free water content is supporting unhealthy microbial growth.
Water activity should not be confused with water content, which is a measure of total moisture by volume. In addition to water activity testing, total moisture testing is important to help contextualize the results of other measurements. For example, a ground flower may be found to have 100 ppb of a particular pesticide, but if it is also found to contain 10% water, then the actual amount of the pesticide would be diluted by that water content.
Water content can vary significantly from sample to sample, so it is important to measure a statistically significant amount of the lot.
