Water Activity in Cannabis
Water Activity in Cannabis
Cannabis-based products for both medicinal and recreational use are gaining in popularity and acceptance. However, if not handled properly, these products can pose a safety issue for consumers. Dried buds, extracted oils, or processed edibles with microbial contamination can result in allergic reactions, respiratory complications, or foodborne illnesses. From a quality standpoint, changes in efficacy and potency due to chemical reactions or structural loss can also result in poor product and lost revenue.
Water activity is utilized as an effective tool in the food and pharmaceutical industries to maximize microbial, chemical, and physical stability. It provides this same safety and control to the cannabis market and it is important that cultivators and processors understand water activity and how to maximize its usefulness. The importance of water activity to the quality and safety of dried Cannabis has resulted in ASTM D8197-18, which establishes 0.55 to 0.65 aw as the ideal water activity range to prevent degradation due to over-drying and prevent microbial growth due to insufficient drying.
WATER ACTIVITY IN CANNABIS AND IT´S MICROBIAL SAFETY
Each microorganism requires a certain water activity to reproduce and grow. If a microorganism encounters a water activity lower than its required growth limit, it will be stressed and become dormant. A microorganism doesn’t care how much water is in its surroundings, but instead requires a certain energy of water to grow.
The water activity level needed for growth by pathogenic bacteria is 0.87 aw while the growth of common spoilage yeasts and molds begins at 0.70 aw, which is known as the practical limit. Dried cannabis flower processed to the ASTM recommended water activity range of 0.55 to 0.65 aw is considered shelf stable and will not support the growth of bacteria, mold or yeast.
The most likely mode of failure for Cannabis when its water activity is too high is mold growth. While molds themselves are not particularly dangerous if consumed, mold spores present a particular concern for Cannabis products since they are often inhaled, resulting in mold spores in the respiratory tract which can lead to asthma symptoms.
WATER ACTIVITY IN CANNABIS AND IT'S STABILITY
WATER ACTIVITY IN CANNABIS AND STORAGE SAFETY / STABILITY
"Water activity plays a key role in ensuring the safety of cannabis products and maximizing shelf life. Water activity may be a new concept to many in the cannabis industry, and those familiar with water activity may only know of its ability to control microbial growth. However, in many cases, microbial spoilage is not the most likely mode of failure for the shelf life of cannabis products. Water activity is related to all common modes of failure and consequently may be the most important test that can be run on everything from harvested biomass to edibles."
Dr. Brady Carter World-renowned specialist in water activity.