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WaterActivity,TheBasicsHelping you make a better measurement.
BruceMcDuffee MichaelBoetzkes
WebinarPresenters
Agenda1. WhatisWaterActivity2. HowdoesWaterActivityrelatetoMoistureContent?3. Whyshouldyoumeasureit?4. Howtomeasureit?
WhatisWaterActivity(Aw)?
• Wateractivityisdefinedasthefreeornon-chemicallyboundwaterinfoods,pharmaceutical,cosmeticsandotherproducts.
WaterActivity&MoistureContent
• WhatisMoistureContent?• Moisturecontentisthepercentageofwaterbyweightintheproductcomparedtothedryorwetweightoftheproductandincludesboththeboundwaterplusthefreewater.Moisturecontentisoftenconfusedwiththewateractivity.
WhyMeasureWaterActivity?
ProductQuality• Texture• Taste• Color• Nutritionalvalue• Shelflife• Safety
WhyMeasureWaterActivity?
Microorganisms
WaterActivity Contaminant
Aw=0.91…0.95 Manybacteria
Aw=0.88 Manyyeasts
Aw=0.80 Manymildews
Aw=0.75 Halophilebacteria
Aw=0.70 Osmiophile yeasts
Aw=0.65 Xerophile mildew
SampleApplication- Food
Awofsomecommonfoods:• LiverPate:0.96RedBean• Paste:0.93• FudgeSauce:0.83• SoySauce:0.80• SoftMoistPetFood:0.83• Caviar:0.92• Salami:0.82
SampleApplication- Pharmaceutical
• ICHQ6ADecisionTree6• USP1112• Improvingantimicrobialeffectivenessofpreservativesystems• Improvingshelflife• Reducedriskofmicrobialcontamination• Rationalforscreeningfrequency
OtherRealWorldApplications
• Cohesionandflowpropertiesofhygroscopicpowders• Adherenceofcoatings• Controlofcakingandcompactionproperties• Dimensionalstabilityofmaterialssuchaspaper• Tensilestrengthandelasticrecovery• Yieldpressureandcompaction
Comments&Questions
Pleasetypeyourquestionsintothechatboxatthelowerleftportionofyourscreen.
HowtoMeasureWaterActivity
SensorTechnology
• CapacitiveSensors• Resistive– Electrolytic• ChilledMirror• LaserTechnologies
BasicsofMeasurement
• EquilibriumRelativeHumidityequatestoAw• Temperatureequilibriumiscritical• Samplepreparationandconsistencyarecriticallyimportant• 5– 45minutesforonemeasurement• Calibrationofsensorsisimportant
SamplePreparation
• Consistentprocedures• Representativesamples• Nottoomuchandnottoolittle• Considerhowcoatingsmayaffectreadings• Limithandlingandexposureoftheproduct• Ensuretemperatureequilibrium• Beawareofcontamination
Summary&Takeaways
1. WaterActivity(Aw)&MoistureContent– differentbutyoucancorrelate
2. Awisanexcellentindicatorofquality,shelflife,safety3. Samplepreparationandconsistentprocessmakethedifference
Comments&Questions
Ifwedon’tgettoyourquestiontoday,we’llrespondviaemailafterthewebinar.
NextWebinars
HowtoReadaPsychrometricChart• Date:Wednesday,April4,2018Time: 1:00- 2:00PMEDT
TheFundamentalsofMeasuringCarbonDioxide• Date: Thursday,May3,2018Time: 1:00- 2:00PMEDT
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