GB 4789.2—2010 Aerobic plate count

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1、GB4789.2—2010NationalfoodsafetystandardFoodmicrobiologicalexamination：AerobicplatecountAerobicplatecountFoodtestsampleistreatedundercertainconditionsafter(e.g.medium,culturetemperatureandculturetime)culture,resultingperg(mL)Thetotalnumberofmicrobialcoloniesformedseizedsamples1EquipmentandM

2、aterialsInadditiontothemicrobiologylaboratoryandtrainingroutinesterilizationequipment,otherequipmentandmaterialsasfollows:1.1incubator:36℃±1℃,30℃±1℃.1.2Refrigerator:2℃~5℃.1.3thermostaticwaterbath:46℃±1℃1.4Balance:asenseoftheamountof0.1g.1.5homogenizer.1.6oscillators.1.7Sterilepipette:1mL(0

3、.01mLwithscale),10mL(0.1mLwithscale)orpipetteandtip.1.8sterileconicalflask:capacity250mL,500mL.1.9sterilePetridish:diameter90mm.1.10pHmeterorpHcolorimetrictubesorprecisionpHtestpaper.1.11magnifierand/orcolonycounter.2mediaandreagents2.1platecountagarmedium:SeeAppendixA,A.1.2.2phosphatebuff

4、er:SeeAppendixAA.2.2.3Sterilesaline:SeeAppendixAA.33InspectionProgramThetotalnumberofcoloniesinspectionprograminFigure1Testsample25g(mL)sample+225mLdiluent,homogeneousReportCalculatethetotalnumberofcolonies10-foldserialdilutionsChoosetwoorthreesuitabledilutionliquidsampleuniform,Fromeach1m

5、LofsterilePetridisheswereaddedwithinEachdishwasadded15mL~20mLPlatecountagarmedium,mixCultureCountthenumberofcoloniesoneachplateFigure1.Thetotalnumberofcoloniesinspectionprocedures4procedure4.1dilutionofsamples4.1.1solidandsemi-solidsamples:Weigh25gsamplesetcontaining225mLofphosphatebuffere

6、dsalinesolutionorsterilehomogeneouswithinthecup,8000r/min~10000r/minhomogenized1min~2minorplacedfilledwith225mLofsterilediluentbaghomogeneous,withslap-typehomogenizerbeat1min~2min,asamplewasevenly1:10.4.1.2Liquidsamples:25mLsterilepipettesamplesetcontaining225mLofphosphatebufferedsalinesol

7、utionorsterileErlenmeyerflask(flaskpresetappropriatenumberofsterileglassbeads),thefullmixthesamplewasmadeuniform1:10.4.1.3with1mLsterilepipetteorpipettetodrawsamples1:10uniformliquid1mL,alongthewallslowlyinjectinasteriletubecontaining9mLdilution(notepipettetip