Hear the word ‘cannabis’ and it’s perhaps an image of spliffs that most readily springs to mind. Things are changing, however. Cannabis products are increasingly promoted in countries or states where consumption of the bi-product CBD is legal.

CBD is already used in everything from biscuits to gummy sweets. To create a safe, edible CBD product, the necessary measures HACCP and QC need to be applied and water activity plays a key role here.

What is CBD?

Wikipedia defines cannabidiol or CBD (not to be confused with cannabinol or cannabinodiol) as, “a naturally occurring cannabinoid constituent of cannabis. It was discovered in 1940 and initially thought not to be pharmaceutically active. It is one of at least 113 cannabinoids identified in hemp plants, accounting for up to 40 per cent of the plant's extract.' As of 2018 in the United States, Food and Drug Administration approval of cannabidiol as a prescription drug called Epidiolex for medical uses has been limited to two rare forms of childhood epilepsy."'’

“Cannabidiol can be taken into the body in multiple different ways, including by inhalation of cannabis smoke or vapor, as an aerosol spray into the cheek, and by mouth. It may be supplied as an oil containing only CBD as the active ingredient (no added THC or terpenes), a full-plant CBD-dominant hemp extract oil, capsules, dried cannabis, or as a prescription liquid solution.‘

“As an ingredient in edibles, CBD is subject to the same food safety standards in cooking, mixing, depositing, cooling, and packaging."

Water activity

Water activity describes the partial vapour pressure of water in a sample in relation to the saturation vapour pressure of pure water. If this is too much chemistry and physics for you, think of it instead as the freely available water in any given product.

Whichever definition you go for, the information that can be gathered by measuring the water activity of sample is relevant. Mold, bacteria and yeast need water not only to survive but to proliferate and thus knowledge of ‘freely available’ water is of vital importance if the CBD product is to stay unaffected by microbiological activity.

Although there is no specific water activity limit for edible cannabis products, the FDA has a 0.85 maximum for non-cannabis products and this limit is applied through the food industry.

Once water activity and microbial risk mitigation has been established, it will help, too, in maintaining product stability, texture and crispness. For those who already have a water activity meter in place, there is good news: the same instrument can be used to get more information about water migration, which influences texture, taste and other sensory properties.

Water Migration

It is a misconception to think that water migrates from a high-moisture to a low- moisture area. Imagine a sea in the valley, a mountain lake and a river connecting the two. If water migration was merely dependent on water from the area where there is more moving to the area where there is less, it would flow from sea to lake. Obviously, though, this is not the case — so, if amount of water is not relevant in migration, something else must be! The water in the mountain lake has a higher potential energy than the water in the sea and water migrates from high to low potential, so it flows downhill. The potential of the free water in a sample is water activity, thus it is now clear why water migrates from a high to low water activity area.

Imagine a CBD edible chocolate or gummy sweet. Beyond any microbial issues, maintaining texture will become a critical factor in this sweet's production: as water starts to migrate it might harden or soften the outer part of the gummy sweet or change the properties of the chocolate coating by adding or removing water. Such problems are familiar to those working in the bakery sector. Any industry offering multilayer CBD products should be talking to its bakery counterparts in order to learn from the issues already encountered within that sector.

How to measure water activity

The basic measurement concept is the same for all water activity manufacturers. A sample is placed in a measurement chamber, which must be completely sealed once closed to avoid humidity exchange with ambient air. Best practice is to have a temperature-control, too, to guarantee a constant of 25°C and thus compliance with AOAC and ISO regulation. What can make the difference is the sensory technology. There are different ones on the market but Novasina's resistive electrolytic technology offers arguably the widest measurement range, highest accuracy and repeatability.

In the CBD industry, the LabMaster-aw neo is well accepted and used by producers, as well as by reference (contractor) labs.The LabMaster-aw neo features a 21CFR1 1 compliant audit trail and user management, full temperature control and automatic calibration and verification procedure.

With an accurate water activity measurement that you can rely on, microbiological and product (texture) stability are far clearer and correct, meaning measures can be implemented throughout the R&D phase. All this avoids the potential for costly and damaging product recalls further down the line.


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