ASTM D8197-22

Standard Specification for Maintaining Acceptable Water Activity (<emph type="ital">a<inf >w</inf></emph>) Range (0.55 to 0.65) for Dry Cannabis Flower Intended for Human/Animal Use

ABSTRACT
This specification prescribes the recommended range of water activity (aw) suitable for safe and efficacious storage of cannabis flowers or portions thereof. Water activity (aw) is defined as the partial vapor pressure of water in a substance divided by the partial vapor pressure of pure water at the same temperature, which can be calculated by dividing the partial vapor pressure of water in the substance by the partial vapor pressure of pure water at the same temperature. This describes quantitatively the capability of the cannabis flower in a sealed container to affect the humidity of the container's headspace air. aw shall be less than 0.65 to ensure against undesirable growth of microorganisms such as mold, and shall be greater than 0.55 to ensure against physical damage (breakage) in routine handling and storage. If aw exceeds 0.68, further drying of the cannabis flower(s) shall be required to ensure that the aw is in the range 0.55–0.65. If aw is less than 0.68, co-storage with a salt-based aw (relative humidity) control sachet(s) designed to maintain the relative humidity between 0.55 to 0.65 can effectively bring the stored cannabis flower(s) into the specified 0.55–0.65 range. Storing cannabis flower with appropriately designed aw (relative humidity) salt-based control sachets intended to ensure a relative humidity of 0.55 to 0.65 in sealed containers can maintain the optimum storage conditions.
Maintaining the requisite aw throughout the supply chain from completion of drying through merchandising ensures safety and quality for the consumer.
SCOPE
1.1 This specification covers the recommended range of aw suitable for safe and efficacious storage of cannabis flowers or portions thereof.  
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Sep-2022
• ICS: 65.020.20 - Plant growing
• Technical Committee: D37 - Cannabis
• Drafting Committee: D37.04 - Processing and Handling

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D8197 −22
Standard Specification for
Maintaining Acceptable Water Activity (a ) Range (0.55 to
w
0.65) for Dry Cannabis Flower Intended for Human/Animal
1
Use
This standard is issued under the fixed designation D8197; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The concept of water activity is more than 50 years old. For many years, researchers tried to equate
bacterial growth potential with water content. William Jones Scott showed in 1953 that microorgan-
2
isms have a limiting a level for growth (1), thus being the first to establish that bacterial growth
w
correlated with water activity, not water content of organic materials. It is now generally accepted that
a is more closely related to the microbial, chemical, and physical properties of foods and other
w
natural products than is total moisture (2). It is firmly established that growth of specific microbes and
metabolism of microbe associated toxins are inhibited at or below specific water activity values (3, 4).
Totalwatercontent(moisture)measurementsdonotnecessarilyreflectwateravailableformicrobial
growth and thus are an inaccurate means for controlling microbial growth, because the water content
sufficientformicrobialgrowthisdependentonthesubstancebeingtested.Wateractivitymeasurement
is more accurate than total water content measurement as it relates directly to the water available (in
liquid form) to microbes and is constant relative to the particular microbe, regardless of the substance
being tested.
1. Scope 2. Referenced Documents
3
2.1 ASTM Standards:
1.1 This specification covers the recommended range of a
w
D8196 Practice for Determination of Water Activity (a )in
w
suitable for safe and efficacious storage of cannabis flowers or
Cannabis Flower
portions thereof.
1.2 This standard does not purport to address all of the 3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro-
3.1.1 water activity, a ,n—the partial vapor pressure of
w
priate safety, health, and environmental practices and deter-
water in a substance divided by the vapor pressure of pure
mine the applicability of regulatory limitations prior to use.
water at the same temperature which is calculated by dividing
the partial vapor pressure of water in the substance (P)bythe
1.3 This international standard was developed in accor-
vapor pressure of pure water at the same temperature (P ), that
dance with internationally recognized principles on standard-
o
is, a = P/(P ). This describes quantitatively the capability of
ization established in the Decision on Principles for the w o
the cannabis flower in a sealed container to affect the humidity
Development of International Standards, Guides and Recom-
of the container’s headspace air.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
4. Significance and Use
4.1 This specification is designed for use on cannabis flower
by cannabis producers, processors, dispensers, testing
1
This specification is under the jurisdiction of ASTM Committee D37 on
laboratories, and end users.
CannabisandisthedirectresponsibilityofSubcommitteeD37.04onProcessingand
Handling.
Current edition approved Oct. 1, 2022. Published November 2022. Originally
3
approved in 2018. Last previous edition approved in 2021 as D8197 – 21. DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/D8197-22. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
2
The boldface numbers in parentheses refer to a list of references at the end of Standards volume information, refer to the standard’s Document Summary page on
this standard. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D8197 − 22
4.2 Analysis and control of water activity should be consid- 6.2 a shall be greater than 0.55 to ensure against physical
w
ered an important quality control step in ensuring a cannabis damage (breakage) in routine handling and storage.
flower sample is being stored under optimal storage conditions
to prevent mold or other microbiological growth and breakage.
7. Special Considerations
4.3 All constituent testing, other than water activity in
7.1 a v
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D8197 − 21 D8197 − 22
Standard Specification for
Maintaining Acceptable Water Activity (a ) Range (0.55 to
w
0.65) for Dry Cannabis Flower Intended for Human/Animal
1
Use
This standard is issued under the fixed designation D8197; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The concept of water activity is more than 50 years old. For many years, researchers tried to equate
bacterial growth potential with water content. William Jones Scott showed in 1953 that microorgan-
2
isms have a limiting a level for growth (1), thus being the first to establish that bacterial growth
w
correlated with water activity, not water content of organic materials. It is now generally accepted that
a is more closely related to the microbial, chemical, and physical properties of foods and other
w
natural products than is total moisture (2). It is firmly established that growth of specific microbes and
metabolism of microbe associated toxins are inhibited at or below specific water activity values (3, 4).
Total water content (moisture) measurements do not necessarily reflect water available for microbial
growth and thus are an inaccurate means for controlling microbial growth, because the water content
sufficient for microbial growth is dependent on the substance being tested. Water activity measurement
is more accurate than total water content measurement as it relates directly to the water available (in
liquid form) to microbes and is constant relative to the particular microbe, regardless of the substance
being tested.
1. Scope
1.1 This specification covers the recommended range of a suitable for safe and efficacious storage of cannabis flowers or portions
w
thereof.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.3 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
3
2.1 ASTM Standards:
D8196 Practice for Determination of Water Activity (a ) in Cannabis Flower
w
1
This specification is under the jurisdiction of ASTM Committee D37 on Cannabis and is the direct responsibility of Subcommittee D37.04 on Processing and Handling.
Current edition approved Feb. 15, 2021Oct. 1, 2022. Published March 2021November 2022. Originally approved in 2018. Last previous edition approved in 20182021
as D8197 – 18.21. DOI: 10.1520/D8197-21.10.1520/D8197-22.
2
The boldface numbers in parentheses refer to a list of references at the end of this standard.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D8197 − 22
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 water activity, a ,n—the partial vapor pressure of water in a substance divided by the partial vapor pressure of pure water
w
at the same temperature which is calculated by dividing the partial vapor pressure of water in the substance (P) by the partial vapor
pressure of pure water at the same temperature (P ), that is, a = P/(P ). This describes quantitatively the capability of the cannabis
o w o
flower in a sealed container to affect the humidity of the container’s headspace air.
4. Significance and Use
4.1 This specification is designed for use on cannabis flower by cannabis producers, processors, dispensers, testing laboratories,
and end users.
4.2 Analysis and control of water activity should be considered an important quality control step in ensuring a cannabis flower
sample is being stored under optimal storage conditions to prevent mold or other microbiological g
...