ASTM_D_8196_-_20.pdf

Designation:D819620Standard Practice forDetermination of Water Activity(aw)in Cannabis Flower1This standard is issued under the fixed designation D8196;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe concept of water activity is more than 50 years old.For many years,researchers tried to equatebacterial growth potential with water content.William Jones Scott showed in 1953 that microorgan-isms have a limiting awlevel for growth(1),2thus being the first to establish that bacterial growthcorrelated with water activity,not water content of organic materials.It is now generally accepted thatawis more closely related to the microbial,chemical,and physical properties of foods and othernatural products than is total moisture(2).It is firmly established that growth of specific microbes isinhibited at or below specific water activity values(3).Total water content(moisture)measurements do not necessarily reflect water available for microbialgrowth and thus are an inaccurate means for controlling microbial growth,because the water contentsufficient for microbial growth is dependent on the substance being tested.Water activity measurementis more accurate than total water content(moisture)measurement as it relates directly to the wateravailable to microbes.Safe awlevels are constant relative to particular microbes,regardless of thesubstance being tested.1.Scope1.1 This practice covers the recommended procedure fordetermining the water activity(aw)of a cannabis flowersample.1.2 UnitsThe values stated in SI units are to be regardedas the standard.Water activity is a ratio,and thus is withoutunit designation.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:3D8197 Specification for Maintaining Acceptable Water Ac-tivity(aw)Range(0.55 to 0.65)for Dry Cannabis Flower3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 cannabis flower,nthe flowering or fruiting tops ofthe cannabis plant(excluding seeds and leaves when notaccompanied by flowering or fruiting top)from which the resinhas not been extracted.(adapted from the UN Single Conven-tion on Narcotic Drugs,19614)3.1.2 cultivator container,npackaging used by cannabisgrower/harvester to store and/or ship product in large quantitiesafter drying.3.1.3 dispensary container,npackaging used by acannabis-dispensing establishment to provide the cannabisflower consumer a satisfactory storage container.3.1.4 packager container,npackaging used by the pack-ager to store and ship product to dispensing establishments.3.1.5 water activity,aw,nthe partial vapor pressure ofwater in a substance divided by the partial vapor pressure of1This practice is under the jurisdiction of ASTM Committee D37 on Cannabisand is the direct responsibility of Subcommittee D37.04 on Processing andHandling.Current edition approved Dec.1,2020.Published December 2020.Originallyapproved in 2018.Last previous edition approved in 2018 as D8196 18.DOI:10.1520/D8196-20.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.4www.unodc.org/pdf/convention_1961_en.pdf,p1,accessed 2018.01.23Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1pure water at the same temperature which is calculated bydividing the partial vapor pressure of water in the substance(P)by the partial vapor pressure of pure water at the sametemperature(Po),that is,aw=P/(Po).This describes quantita-tively the capability of the cannabis flower in a sealed containerto affect the humidity of the containers headspace air.4.Summary of Practice4.1 The water