High resolution melting analysis of DNA microsatellites in olive pastes and virgin olive oils obtained by talc addition

Talc(hydratedmagnesiumsilicate)is a physicalcoadjuvantthat can be employedin the productionofextravirginoliveoil to increaseyield.Theadsorbentpropertiesof talc couldhamperDNArecovery,leadingto falsenegativesin DNAanalysis.Theaim of this workwas to verifythe effectof talc additionon oliveoil DNAby targetingfourselectedmicrosatellites.Oliveprocessingtrialswerecarriedout attwo differentlevelsof talc (1 and 2%)and withouttalc (control).DNAextractionyieldand puritylevelwereascertained,and HighResolutionMelting(HRM)analysisof microsatelliteswas subsequentlyappliedto the extractedDNA.Neitherthe DNAextractionyieldnor the A260/230and A260/280ratiosshowedsignificantdifferencesbetweencontroland talc-treatedsamples.Highervaluesof A260/230andloweryieldswereobservedin oliveoils thanin olivepastes.TheDNAmicrosatellitesanalyzedshowedidenticalHRMprofilesin all the samples,excludingany effectof talc andconfirmingthe genetichomogeneityof the olivelot processed(cv.Coratina).Practicalapplications:Highadded-valuemono-cultivarextravirginoliveoils are nicheproductsveryappreciatedby consumers.DNAanalysisis ableto revealmixingwithcultivarsdifferentfromthosedeclaredin the label.Theuse of talc in oliveoil industrieshas progressivelyincreasedto improveyield.Theresultsobtainedprovethat the DNA-basedmethodsset up untilnowto checkthe authenticityofextravirginoliveoil can be effectivelycarriedout also in oils producedby usingtalc.In addition,theresultsare amongthe first applicationsof HRMto the foodsectorand evidencethe feasibilityof thistechniquealongthe oliveoil chainfor checkingbotholivepastesand oils