3/19/14UCDAVISMethodstoDetermineOxidationExtraVirginOliveOilSensoryMethodsFreeFattyAcidsPeroxideValueConjugated DienesCarbonylCompounds·TBAValueGasChromatographicMethodsOLIVEFluorescenceMethodsCENTEPERCENTAGEOFSAMPLESFAILINGSENSORYTheInternational OliveCommittee'sPANELSTHATWERECONFIRMEDBYCHEMICALTESTS(IOC)olive oil standardsFree fatty acidity values provide an indication of how the fruit washandled prior to processing and the length of time from harvest to milling.Free acidity is also an early indicator of the potential longevity of the oil.LUONI200000It may be no higher than 0.35% in extra virgin olive oils (EVOO),0733FILIPPOBERIO00STAR1164Peraxide Values It should shown a value no greater thatn 20meq/ig.Experience indicates that highquality, recently miled oils exhibit peroxide62BERTOLLI130values below 12 meq/kg- Truly excellent oils may have PV as low as 7 meq/kgCOLAVITA10070(9 meq/kg for.organic oil).17POMPEIANas1000AVE,ALL68001265OUV abs0rbance, the standards callfor K232 absorbance values below2.5BRANDSLow values correlate with high-quality oil, as UV absorbance detects early andlater states of oxidation.1
3/19/14& 1& Extra Virgin Olive Oil . • Sensory Methods • Free Fatty Acids • Peroxide Value • Conjugated Dienes • Carbonyl Compounds • TBA Value • Gas Chromatographic Methods • Fluorescence Methods Methods to Determine Oxidation The International Olive Committee’s (IOC) olive oil standards Free$fa'y$acidity$values provide&an&indica1on&of&how&the&fruit&was& handled&prior&to&processing&and&the&length&of&1me&from&harvest&to&milling.& Free&acidity&is&also&an&early&indicator&of&the&poten1al&longevity&of&the&oil.&& It&may&be&no&higher&than&0.35%&in&extra&virgin&olive&oils&(EVOO).&& Peroxide$Values$It&should&shown&a&value&no&greater&thatn&20&meq/kg.& Experience&indicates&that&highLquality,&recently&milled&oils&exhibit&peroxide& values&below&12&meq/kg.&Truly&excellent&oils&may&have&PV&as&low&as&7&meq/kg& (9&meq/kg&for&organic&oil).&& UV$absorbance,&the&standards&call&for&K232&absorbance&values&below&2.5.& Low&values&correlate&with&highLquality&oil,&as&UV&absorbance&detects&early&and& later&states&of&oxida1on.& PERCENTAGE$OF$SAMPLES$FAILING$SENSORY$ PANELS$THAT$WERE$CONFIRMED$BY$CHEMICAL$TESTS BRAND$ #$OF$ SAMPLES$ FAILING$ SENSORY$ PANELS$ Free$ Fa'y$ Acids$ Fa'y$ acid$$ Profile$ Peroxide$ Value$ UV$ K232$ DAGs$ LUCINI& 2& 0& 0& 0& 0& 0& FILIPPO&BERIO& 15& 0& 0& 0& 7& 33& STAR& 11& 0& 0& 0& 0& 64& BERTOLLI& 13& 0& 0& 0& 8& 62& COLAVITA& 10& 0& 0& 0& 0& 70& POMPEIAN& 17& 0& 0& 0& 35& 100& AVE,&ALL& BRANDS& 68& 0& 0& 0& 12& 65&
3/19/14MethodsofOliveOilAnalysisAcidityfromLipolysis:Acidity Free Fatty AcidsFactors Acidity ValueNC-OH MicrobialHoa·OxidationORCOOH+ EnzymesP1-Peroxide ValueTemperaturedroer-UVAbsorption Moisture:CompositionofFattyAcidsPreparation of Methyl Esters-DeterminationbyCapillaryGLCKiritsakis, 1998AcidityLimits(IOOC)I.FreeFattyAcidsFreeFaty Acids (%olelc acid)Category.Percentagebyweight ofa specifiedfatty acid0.9ExtraVirginOlive Oil(e.g.,%oleicacid)<2.1Virgin Olive OilOrdinary VirginOlive Oll<3.4Applicable to all crude and refined vegetable·Lampante Oil>3.3oils,marineoils,andanimalfatsRefined Oil<0.4Olive Oll<.1Crude Olive Residue OiNoLimitRefined Olive Residue Oll<0.4Olive Residue Oll<.1AOCS Official Method Ca 5a-40Kiritsakis, 19982
3/19/14& 2& Methods&of&Olive&Oil&Analysis& • Acidity& – Free&Fa^y&Acids& – Acidity&Value& • Oxida1on& – Peroxide&Value& – UV&Absorp1on& • Composi1on&of&Fa^y&Acids& – Prepara1on&of&Methyl&Esters& – Determina1on&by&Capillary&GLC& Acidity&from&Lipolysis& • Factors& – Microbial& – Enzymes& – Temperature& – Moisture& Kiritsakis,&1998& Acidity&Limits&(IOOC)& Category$ Free$Fa'y$Acids$(%$oleic$acid)$ Extra&Virgin&Olive&Oil& <0.9& Virgin&Olive&Oil& <2.1& Ordinary&Virgin&Olive&Oil& <3.4& Lampante&Oil& >3.3& Refined&Oil& <0.4& Olive&Oil& <1.1& Crude&Olive&Residue&Oil& No&Limit& Refined&Olive&Residue&Oil& <0.4& Olive&Residue&Oil& <1.1& Kiritsakis,&1998& I.&&&Free&Fa^y&Acids& • Percentage&by&weight&of&a&specified&fa^y&acid& (e.g.,&%&oleic&acid)& • Applicable&to&all&crude&and&refined&vegetable& oils,&marine&oils,&and&animal&fats& AOCS&Official&Method&Ca&5aL40&
3/19/141I.FreeFattyAcidsProcedureAcidValueWeigh the designated sample size into an oil sampleAmountof KOH (mg)neededto neutralize thebottleorErlenmeyerflask.(Capbottleandshakefree fatty acids in 1g of samplevigorouslyfor1min if oil has been blanketed withcarbon dioxide gas.)Applicableto crude and refined animal,.:Add the specified amount ofhot neutralized alcoholvegetable, and marine fats and oils, andand 2mL of indicator.various productsderivedfrom them.Titrate with standard sodium hydroxide, shakingvigorouslyuntil the appearance of the first permanentpink color of the same intensity as that of theneutralized alcohol before the addition of the sample.The color must persist for 30 seconds.AOCS Official Method Ca 5a-40AOCS Official Method Cd 3d-631.UVAbsorbanceK2a2: Measure conjugated dienes.K2o: Measure conjugated trienes Determines conjugated hydroperoxides formed as primary:Detects substances formed during earth treatment in refiningoxidation productsprocess(Rss+Rga)A=K,_(++kmdAKRzK.isthespecificextinctionatwavelengthwithmaximumabsorbance (270 nm)..Lowabsorbancevaluescorrespondtogoodquality olive oil.AOAC Official Method Ch 5-913
3/19/14& 3& Free&Fa^y&Acids&Procedure& • Weigh&the&designated&sample&size&into&an&oil&sample& bo^le&or&Erlenmeyer&flask.&(Cap&bo^le&and&shake& vigorously&for&1&min&if&oil&has&been&blanketed&with& carbon&dioxide&gas.)& • Add&the&specified&amount&of&hot&neutralized&alcohol& and&2&mL&of&indicator.& • Titrate&with&standard&sodium&hydroxide,&shaking& vigorously&un1l&the&appearance&of&the&first&permanent& pink&color&of&the&same&intensity&as&that&of&the& neutralized&alcohol&before&the&addi1on&of&the&sample.&& The&color&must&persist&for&30&seconds.&& AOCS&Official&Method&Ca&5aL40& II.&&&&Acid&Value& • Amount&of&KOH&(mg)&needed&to&neutralize&the& free&fa^y&acids&in&1&g&of&sample& • Applicable&to&crude&and&refined&animal,& vegetable,&and&marine&fats&and&oils,&and& various&products&derived&from&them& AOCS&Official&Method&Cd&3dL63& • K232:&&Measure&conjugated&dienes& • Determines&conjugated&hydroperoxides&formed&as&primary& oxida1on&products& I.&UV&Absorbance& AOAC&Official&Method&Ch&5L91& • K270:&&Measure&conjugated&trienes& • Detects&substances&formed&during&earth&treatment&in&refining& process& – Kmax&is&the&specific&ex1nc1on&at&wavelength&with& maximum&absorbance&(270&nm).&& • Low&absorbance&values&correspond&to&good& quality&olive&oil.&
3/19/14Calculations:UltravioletAbsorptionBeer s Law::A=ebc0.25g oil +25rExPure isooctane/Ka= Pure cyclohexaneACXS=bXcK, = specific extinction at,E, = extinction measured at,A=absorbance-S = thickness of the cuvetteRecord Abs @ 232nm, 268nm, 262nm, 272nme =molar absorbtivity (mor’ cm-)(cm)b =path length (cm):C =concentration of thec =concentration of the compoundsolution(g/100mL)in solution (mol L-1)K=Abs/Conc.AOACOfficialMethodCh5-91AOACOfficialMethodCh5-91Procedures-BackTitrationIl.PeroxideValueOll sample50ml 3:2 acetic acid + isooctane solutionExtentofoxidationPrimarvproduct-Earlvstageofoxidation250mlBlueDtsapceared0.1M Na,5,0,0.5ml Sat. KISit for 1 minYellow Disappeared(keep shaking)0.5ml 10% SDS0.5ml starch indicator8OmI Distilled H,CAOAC Official Method Cd Sb-90a
3/19/14& 4& Ultraviolet&Absorp1on& 0.25g&Oil&&+&&& Pure&isooctane/& Pure&cyclohexane& Record&Abs&@&232nm,&268nm,&262nm,&272nm& 25ml& AOAC&Official&Method&Ch&5L91& • Kλ&=&specific&ex1nc1on&at&λ • E&λ&=&ex1nc1on&measured&at&λ • S&=&thickness&of&the&cuve^e,& (cm)& • C&=concentra1on&of&the& solu1on&(g/100mL)&& • K=Abs/Conc.$ Calcula1ons:& • Beers&Law&:& • A&=ebc& • A&=absorbance&& • e&=molar&absorb1vity&(molL1&cmL1)& • b&=path&length&(cm)& • c&=concentra1on&of&the&compound& in&solu1on&(mol&LL1)& AOAC&Official&Method&Ch&5L91& II.&Peroxide&Value& • Extent&of&oxida1on& • Primary&product&–&Early&stage&of&oxida1on& ProceduresL&Back&Titra1on& Oil&sample& 50ml&3:2&ace1c&acid&+&isooctane&solu1on& 0.5ml&Sat.&KI& Sit&for&1&min& (keep&shaking)& 30ml&Dis1lled&H2O& 0.1M&Na2S2O3& 0.5ml&10%&SDS& 0.5ml&starch&indicator& Yellow&Disappeared& Blue&Disappeared& 250ml& AOAC&Official&Method&Cd&8bL90&
3/19/14GasChromatographyCCmethodsInjectorComputerorDetectorInjectorHanjiang ZhuovenovenTypicalyTprogranmingiscohurequired, whichprovides a basis forthe separation ofColumn ovensample componentsbased onBP.OuterwailofcolumnCapillarycolumns0.10.53mminner.diameteStationary phase(0.15 μm mick)(a)ars000Column.wallWal-coatedSuppon-coatedPorousapentubusntubulartubularCoucolumncolumn(SCOT)(WCOT)(PLOT)(e)5
3/19/14& 5& GC Methods Hanjiang Zhu Gas$Chromatography$ Typically&T& programming&is& required,&which& provides&a&basis&for& the&separa1on&of& sample&components& based&on&BP.& Capillary$columns$