The quality of post-harvest cannabis flower is closely related to one single metric: Water Activity (aW). Let's have a look at why you should be closely watching water activity along your cannabis value chain and why current regulations based on Moisture Content (MC) or Loss of Drying (LoD) are just not good enough.

1. 5 Reasons to
Measure Water
Activity (aW) in
Cannabis Flower
And Why Moisture Content or
Loss of Drying Isn’t Useful At All
*
© 2020 Benjamin Patock
C A N N A B I S K N O W L E D G E
© 2 0 2 0 B E N J A M I N P A T O C K

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© Boveda Inc.

3. 1)
aW is 100%
Qualitative
• Moisture content (MC) or loss of drying (LoD)
describe the relative amount of water in the
total weight of the flower – quantitatively
• Water activity (aW) describes how much
“energy” this moisture has in order to fuel
biochemical processes, such as microbial
growth
• International bodies therefore recognize water
activity to be used as common standard to
regulate moisture in cannabis flower*
* ASTM D8197-18: Standard Specification for Maintaining Acceptable Water Activity (aw) Range (0.55 to 0.65) for Dry Cannabis Flower

4. 2) High aW Leads to Microbial Pollution
• Any water activity above 0.65 aW
triggers an accelerated growth of
molds, mildew, yeasts, and bacteria
• It is therefore imperative to store
dried cannabis flower under this
threshold at all times – from bulk
processing to final consumption
Rockland, Stewart (1981); Water Activity: Influences on Food Quality, Academic Press

5. 3)
Low aW
Leads to
Accelerated
Terpene Loss
• Drying a cannabis plant always comes with a
loss of volatiles such as terpenoids and
flavonoids in the process
• Storing cannabis flower below 0.55 aW can
accelerate this process – even when stored in
high-barrier packaging. Certain chemovars can
lose up to 40% of their terpenes in a matter of
days in closed containers
• Therefore, it is recommended to store cannabis
flower at 0.55 - 0.65 aW to maintain a high-
quality and safe product*
* ASTM D8197-18: Standard Specification for Maintaining Acceptable Water Activity (aw) Range (0.55 to 0.65) for Dry Cannabis Flower

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© Boveda Inc.

7. 4) aW is Universal
• Different chemovars have different
capabilities of storing moisture in their
cell structure
• The relation between water activity
and moisture content is not linear
• Therefore, thresholds based on
moisture content would have to be
established for each chemovar
individually
*
Table Data © Boveda Inc.
MC | aW MC | aW MC | aW

8. 5)
Assessing aW
is Fast, Easy,
and Without
Any Loss
• Albeit assessing moisture content or loss of
drying is widely standardized and can be
executed by any laboratory, it is time-
consuming and involves the destruction of the
sample
• Electronic water activity analyzers are easy to use
and provide fast and reliable measurements on
site
• And: measuring water activity does not affect
the sample at all. It can be reintegrated into the
production process
* ASTM D8197-18: Standard Specification for Maintaining Acceptable Water Activity (aw) Range (0.55 to 0.65) for Dry Cannabis Flower

9. Interested in Proactively
Managing Water Activity
In Your Products?
*
Contact me at your convenience!

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© Boveda Inc.

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© 2020 Benjamin Patock
B E N J A M I N PAT O C K
w w w .lin k ed in .co m/in /patock/