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

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