Water Activity 102 - The Importance of Free & Bound Water in Cannabis Curing
Lee Hymers
Co-Founder of Yofumo Africa, Legacy Cultivator, Horticulture, CEA Specialist, Medical Cannabis Consultant & Biotechnology Researcher
In my last post I discussed the importance of water activity in microbial control. In this article, we shall go a little further down the rabbit hole in order to look at it from another perspective and further appreciate how the relationship between bound and free water within the cannabis flower itself, helps determine its final quality and ultimately its market value.
One of the major problems I repeatedly see as a consultant in the legal cannabis space, is the fact that the vast majority of the more profit focused commercial growers sell their dried product as soon as they can and simply forgo the curing process....why...because curing takes time (and time = money.) Thinking this way is a mistake and if you'll allow me I'll explain why.
Previously we discussed how water activity is an important parameter in determining the quality, stability and microbial safety of dried cannabis flower. In this context, free water and bound water both play important roles.
Free water in dried cannabis flower refers to the moisture that is present in the form of liquid water and is available to participate in chemical reactions and microbial growth. This water can be removed from the flower by simple physical processes such as evaporation or drying. The presence of free water in cannabis flower can lead to microbial growth and degradation of the flower's quality and potency.
Bound water in dried cannabis flower refers to the moisture that is tightly bound to the surface of the flower's organic compounds, such as cannabinoids and terpenes. This water is not available to participate in chemical reactions or microbial growth and is often referred to as "unavailable" water. Bound water in cannabis flower can affect the flower's water activity, as it can decrease the amount of free water and increase the stability of the flower. Bound water can be removed from the flower by more extreme physical or chemical processes, such as heating or freezing.
Both types of water play important roles in determining the quality and stability of dried cannabis flower, and their management is critical for maintaining the flower's potency and safety.
That being said, the best method currently available for increasing the amount of bound water within cannabis flower while decreasing the amount of free water,?is through what we all know as curing.
During the curing process, the cannabis flower is carefully dried and aged under controlled conditions of temperature, humidity, and airflow. This allows for the gradual release of free water from the plant material, while the bound water becomes more tightly bound to the plant material.
Biologically and physiologically, curing allows for the breakdown of complex carbohydrates and proteins within the plant material, leading to the release of sugars and amino acids. These compounds then react with the remaining moisture in the flower to form complex molecules that contribute to the plant's aroma, flavor, and therapeutic effects.
Additionally, during the curing process, enzymes within the plant material continue to break down chlorophyll, which can lead to a more pleasant flavor and aroma. This process also allows for the conversion of non-psychoactive cannabinoids, such as cannabidiolic acid (CBDA), into psychoactive cannabinoids, such as tetrahydrocannabinol (THC).
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The effects of curing on the chemical composition of cannabis flower can be significant. Specifically, curing can lead to changes in the concentration of lipids, cannabinoids, and terpenes.
Lipids are fatty acids found in cannabis flower that are responsible for carrying and storing cannabinoids and terpenes. During curing, the breakdown of lipids slows down, leading to an increase in the concentration of lipids in the flower. This can result in a smoother and more flavorful smoke or vapor when consumed.
Cannabinoids are the chemical compounds found in cannabis flower that are responsible for the plant's therapeutic effects. During curing, cannabinoids can become more concentrated as the plant material dries out, leading to a more potent product. However, if the curing process is not done correctly, the concentration of cannabinoids can decrease.
Terpenes are aromatic compounds found in cannabis flower that give each strain its distinct aroma and flavor. Curing can help to preserve the terpene profile of the flower, leading to a more flavorful and aromatic product. However, if the curing process is not done correctly, terpenes can be lost or degraded, resulting in a less desirable product.
In addition to these chemical changes, curing can also have a significant impact on water activity and microbiological behavior. Water activity is a measure of the amount of free water available in a substance, and it is an important factor in determining microbial growth and spoilage. During curing, the gradual release of free water from the plant material leads to a decrease in water activity, can help to prevent the growth of harmful microorganisms.
Overall, the curing process is a delicate dance between removing excess moisture and preserving the integrity of the plant material. When done correctly, curing can lead to a more potent, flavorful, and aromatic product with an increased amount of bound water and decreased amount of free water, as well as a reduced risk of microbial growth and spoilage.
Knowing the above, what I tell my clients is this:
At the end of the day the decision lies with you but in the cannabis world, be it legal or otherwise, quality trumps quantity every time. The market will always pay a premium for those reaching the bar, but it will pay more for those rising above it.