Peb siv cov ncuav qab zib los txhim kho koj qhov kev paub.Los ntawm txuas ntxiv mus saib lub vev xaib no, koj pom zoo rau peb siv cov ncuav qab zib.Xav paub ntxiv.
Ib qho khoom tseem ceeb hauv npias yog hops.Nyob rau hauv cov flavors ntawm ntau npias, lawv muab ib qho tseem ceeb tshuav nyiaj li cas rau malt.Lawv kuj pab kom precipitate proteins thiab lwm yam thaum lub sij hawm boiling.Hops kuj muaj cov khoom khaws cia, uas pab kom cov npias tshiab thiab tsis muaj kab mob.
Muaj ntau hom hops thiab ntau yam khoom qab zib muaj.Txij li thaum lub tsw yuav txo qis thaum lub sij hawm, hops yuav tsum tau muab khaws cia kom zoo thiab siv thaum lawv tshiab.Yog li ntawd, qhov zoo ntawm hops yuav tsum yog tus cwj pwm kom tus brewer tuaj yeem tsim thiab xa cov khoom xav tau.
Muaj ntau lub tebchaw hauv hops uas tuaj yeem cuam tshuam rau qhov tsw, yog li qhov aroma ntawm hops yog qhov nyuaj heev.Cov khoom ntawm cov hops raug teev nyob rau hauv Table 1, thiab Table 2 teev qee qhov tseem ceeb aroma compounds.
Cov txheej txheem ib txwm siv los ntsuas qhov zoo ntawm hops yog cia tus kws paub txog brewer tsoo qee qhov hops nrog nws tus ntiv tes, thiab tom qab ntawd hnov ​​​​cov ntxhiab tsw tso tawm los ntsuas cov hops los ntawm kev nkag siab.Qhov no siv tau tab sis tsis yog lub hom phiaj, thiab tsis muaj cov ntaub ntawv xav tau los txiav txim siab txog kev siv hops.
Txoj kev tshawb no qhia txog cov txheej txheem uas tuaj yeem ua lub hom phiaj tshuaj ntsuam xyuas ntawm hop aromas los ntawm kev siv roj chromatography / huab hwm coj spectrometry, thaum tseem muab cov neeg siv nrog ib txoj hauv kev los saib xyuas qhov kev xav ntawm olfactory ntawm txhua lub ntsiab lus eluted los ntawm chromatographic kem feature.
Static headspace (HS) sampling yog qhov tsim nyog rau kev rho tawm cov tshuaj tsw qab los ntawm hops.Raws li pom nyob rau hauv daim duab 1, muab cov hops hnyav (particles los yog nplooj) rau hauv ib lub khob vial thiab kaw nws.
Daim duab 1. Hops tos rau kev tsom xam nyob rau hauv lub taub hau qauv lub raj mis.Duab qhov chaw: PerkinElmer Food Safety and Quality
Tom ntej no, lub vial yog rhuab nyob rau hauv ib lub qhov cub ntawm ib tug teem taag kub rau ib lub sij hawm taag lub sij hawm.Lub headspace sampling system rho tawm ib co vapor los ntawm lub vial thiab qhia nws mus rau hauv GC kem rau kev sib cais thiab tsom xam.
Qhov no yooj yim heev, tab sis zoo li qub headspace txhaj tshuaj tsuas yog muab ib feem ntawm lub taub hau vapor mus rau GC kem, yog li nws yog qhov zoo tshaj plaws rau cov ntsiab lus siab.
Nws feem ntau pom tau tias nyob rau hauv kev tshuaj xyuas ntawm cov qauv nyuaj, cov ntsiab lus tsis tshua muaj ntawm qee yam khoom tseem ceeb rau tag nrho cov aroma ntawm cov qauv.
Lub headspace ntxiab system yog siv los nce tus nqi ntawm cov qauv qhia rau hauv GC kem.Siv cov thev naus laus zis no, feem ntau lossis txawm tias tag nrho lub taub hau vapor dhau los ntawm cov cuab yeej adsorption los sau thiab mloog zoo VOC.Cov ntxiab yog tom qab cua sov sai, thiab cov khoom desorbed raug xa mus rau GC kem.
Siv cov qauv no, cov qauv vapor nkag mus rau GC kem tuaj yeem nce mus txog 100 zaug.Nws yog heev haum rau hop aroma tsom xam.
Cov duab 2 txog 4 yog qhov yooj yim sawv cev ntawm kev ua haujlwm ntawm HS ntxiab-lwm li qub thiab cov kav dej kuj tseem xav tau los xyuas kom meej tias cov qauv vapor mus txog qhov twg nws yuav tsum nyob.
Daim duab 2. Schematic daim duab ntawm HS ntxiab system, uas qhia qhov sib npaug vial raug pressurized nrog cov cab kuj roj.Duab qhov chaw: PerkinElmer Food Safety and Quality
Daim duab 3. Schematic daim duab ntawm H2S ntxiab system uas qhia qhov tso tawm ntawm lub taub hau pressurized los ntawm lub vial mus rau hauv lub adsorption ntxiab.Duab qhov chaw: PerkinElmer Food Safety and Quality
Daim duab 4. Schematic daim duab ntawm HS ntxiab system, uas qhia tias VOC sau nyob rau hauv lub adsorption ntxiab yog thermally desorbed thiab nkag mus rau hauv GC kem.Duab qhov chaw: PerkinElmer Food Safety and Quality
Lub hauv paus ntsiab lus yog zoo ib yam li classic zoo li qub headspace nyob rau hauv lub essence, tab sis tom qab lub vapor pressurization, thaum kawg ntawm lub vial equilibration kauj ruam, nws yog kiag li emptied los ntawm cov adsorption ntxiab.
Txhawm rau kom ua tiav tag nrho lub taub hau vapor los ntawm cov cuab yeej adsorption, cov txheej txheem tuaj yeem rov ua dua.Thaum lub ntxiab tau thauj khoom, nws tau ua kom sov sai thiab lub desorbed VOC raug xa mus rau GC kem.
Lub workhorse Clarus® 680 GC yog ib qho zoo tagnrho ntxiv rau lwm qhov system.Txij li thaum chromatography tsis xav tau, cov tswv yim yooj yim tuaj yeem siv tau.Nws yog ib qho tseem ceeb kom muaj sij hawm txaus nyob nruab nrab ntawm cov peaks uas nyob ib sab rau kev soj ntsuam olfactory kom tus neeg siv tuaj yeem paub qhov txawv ntawm ib leeg.
Kev thauj khoom ntau npaum li qhov ua tau mus rau hauv kab chromatographic kem yam tsis muaj overloading kuj pab muab cov neeg siv lub qhov ntswg nrog lub sijhawm zoo tshaj plaws los kuaj xyuas lawv.Vim li no, ib kem ntev nrog cov tuab nyob ruaj ruaj yog siv.
Siv ib tug heev polar Carbowax® hom nyob ruaj ruaj theem rau kev sib cais, vim hais tias muaj ntau yam (ketones, acids, esters, thiab lwm yam) nyob rau hauv hops yog heev polar.
Txij li cov kem effluent xav tau los muab MS thiab qhov chaw nres nkoj olfactory, yuav tsum muaj qee daim ntawv cais.Qhov no yuav tsum tsis txhob cuam tshuam rau kev ncaj ncees ntawm chromatogram nyob rau hauv txhua txoj kev.Yog li ntawd, nws yuav tsum tau inert heev thiab muaj ib tug tsawg-ntim sab hauv geometry.
Siv cov roj pleev xim rau hauv lub tshuab hluav taws xob kom ruaj khov thiab tswj qhov sib cais ntws.S-SwaferTM yog ib qho khoom siv spectroscopic zoo heev uas tsim nyog rau lub hom phiaj no.
Lub S-Swafer tau teeb tsa kom faib cov kab dej ntws tawm ntawm MS detector thiab SNFR olfactory chaw nres nkoj, raws li pom hauv daim duab 6. Qhov sib cais ntawm tus ntes thiab qhov chaw nres nkoj olfactory txhais tau hais tias MS thiab SNFR los ntawm kev xaiv lub raj txwv tsis pub sib txuas ntawm swap qhov hluav taws xob thiab qhov chaw nres nkoj olfactory.
Daim duab 6. S-Swafer configured rau siv nrog Clarus SQ 8 GC/MS thiab SNFR.Duab qhov chaw: PerkinElmer Food Safety and Quality
Lub Swafer utility software txuas rau Swafer system tuaj yeem siv los xam qhov sib cais no.Daim duab 7 qhia yuav ua li cas siv lub laij lej no los txiav txim siab ua haujlwm ntawm S-Swafer rau daim ntawv thov no.
Daim duab 7. Cov khoom siv hluav taws xob Swafer qhia tau hais tias cov chaw siv rau qhov haujlwm no hop aroma characterization.Duab qhov chaw: PerkinElmer Food Safety and Quality
Qhov loj spectrometer yog ib feem tseem ceeb ntawm aroma characterization system.Nws yog ib qho tseem ceeb tsis yog tsuas yog txhawm rau txheeb xyuas thiab piav qhia txog cov aroma ntawm ntau yam khoom eluting los ntawm GC kem, tab sis kuj yuav txiav txim siab seb cov khoom no yog dab tsi thiab lawv yuav muaj nyob rau hauv lub hops.
Vim li no, Clarus SQ 8 quadrupole mass spectrometer yog qhov kev xaiv zoo tshaj plaws.Nws yuav ceev nrooj txheeb xyuas thiab ntsuas cov khoom siv siv cov khoom siv classical hauv NIST lub tsev qiv ntawv.Lub software kuj tuaj yeem cuam tshuam nrog cov ntaub ntawv olfactory tau piav qhia tom qab hauv qhov kev tshawb fawb no.
Daim duab ntawm daim ntawv txuas SNFR yog pom hauv daim duab 8. Nws txuas nrog GC los ntawm cov kab hloov pauv hloov pauv hloov tau yooj yim.Qhov sib cais kem dej ntws los ntawm qhov deactivated fused silica raj mus rau lub khob qhov ntswg clamp.
Tus neeg siv tuaj yeem ntes cov lus piav qhia los ntawm lub microphone built-in, thiab saib xyuas cov aroma siv ntawm cov aroma compounds eluted los ntawm GC kem los ntawm kev kho lub joystick.
Daim duab 9 qhia txog tag nrho cov ion chromatogram (TIC) ntawm plaub lub hops los ntawm ntau lub teb chaws.Ib feem ntawm Hallertau hauv lub teb chaws Yelemees yog qhov tseem ceeb thiab nthuav dav hauv daim duab 10.
Daim duab 9. Hom TIC chromatogram ntawm plaub-hop qauv.Duab qhov chaw: PerkinElmer Food Safety and Quality
Raws li pom nyob rau hauv daim duab 11, cov yam ntxwv muaj zog ntawm MS tso cai rau cov peaks tshwj xeeb los txheeb xyuas los ntawm lawv cov duab loj los ntawm kev tshawb nrhiav NIST lub tsev qiv ntawv suav nrog Clarus SQ 8 system.
Daim duab 11. Qhov loj spectrum ntawm lub ncov tseem ceeb nyob rau hauv daim duab 10. Image Source: PerkinElmer Food Safety and Quality
Daim duab 12 qhia cov txiaj ntsig ntawm kev tshawb fawb no.Lawv qhia tau hais tias lub ncov eluting ntawm 36.72 feeb yog 3,7-dimethyl-1,6-octadien-3-ol, los yog linalool.
Daim duab 12. Cov ntaub ntawv tshawb fawb hauv tsev qiv ntawv loj tau pom hauv daim duab 11. Duab qhov chaw: PerkinElmer Food Safety and Quality
Linalool yog ib qho tseem ceeb aroma compound uas muaj peev xwm muab tau ib tug mos floral tsw rau npias.Los ntawm calibrating GC / MS nrog cov qauv sib xyaw ntawm cov khoom sib xyaw no, tus nqi ntawm linalool (los yog lwm yam kev txheeb xyuas) tuaj yeem suav tau.
Daim ntawv qhia kev faib tawm ntawm cov yam ntxwv hop tuaj yeem tsim los ntawm kev txheeb xyuas cov chromatographic peaks.Daim duab 13 qhia pom ntau lub ncov pom nyob rau hauv Hallertau chromatogram ntawm lub teb chaws Yelemees pom hauv daim duab 9 ua ntej.
Daim duab 13. Hom TIC chromatogram ntawm plaub-hop qauv.Duab qhov chaw: PerkinElmer Food Safety and Quality
Cov lus piav qhia saum toj kawg nkaus yog cov fatty acids, qhia txog qib ntawm oxidation ntawm hops hauv cov qauv no.Cov nplua nuj myrcene ncov me dua li qhov xav tau.
Cov kev soj ntsuam no qhia tau hais tias tus qauv no yog qhov qub (qhov no yog qhov tseeb-qhov no yog ib qho qauv qub uas yog khaws cia tsis raug).Cov chromatograms ntawm plaub tus qauv hop ntxiv yog qhia hauv daim duab 14.
Daim duab 14. TIC chromatogram ntawm ib qho piv txwv plaub-hop ntxiv.Duab qhov chaw: PerkinElmer Food Safety and Quality
Daim duab 15 qhia tau hais tias ib qho piv txwv ntawm hla chromatogram, qhov twg cov lus piav qhia thiab siv cov ntaubntawv povthawj siv yog graphically superimposed.Cov lus piav qhia yog khaws cia rau hauv cov qauv WAV cov ntaub ntawv thiab tuaj yeem ua si rov qab rau tus neeg teb xov tooj los ntawm qhov screen no ntawm txhua qhov taw qhia hauv chromatogram uas pom nrog tus nas yooj yim nyem.
Daim duab 15. Ib qho piv txwv ntawm lub plhaw chromatogram tau pom hauv TurboMass™ software, nrog rau cov lus piav qhia thiab aroma siv cov duab.Duab qhov chaw: PerkinElmer Food Safety and Quality
Narration WAV cov ntaub ntawv kuj tseem tuaj yeem ua si los ntawm ntau daim ntawv thov tshaj tawm, suav nrog Microsoft® Media Player, uas suav nrog Windows® operating system.Thaum kaw, cov ntaub ntawv suab tuaj yeem hloov mus rau hauv cov ntawv.
Txoj haujlwm no yog ua los ntawm Nuance® Dragon® Ib txwm hais lus software suav nrog hauv SNFR cov khoom.
Daim ntawv tshaj tawm kev soj ntsuam hop ib txwm qhia cov lus piav qhia los ntawm tus neeg siv thiab cov aroma siv tau kaw los ntawm lub joystick, raws li pom nyob rau hauv Table 9. Cov hom ntawv ntawm daim ntawv tshaj tawm yog cov ntaub ntawv comma-separated value (CSV), haum rau ncaj qha ntshuam rau hauv Microsoft® Excel® lossis lwm yam kev siv software.
Table 9. Ib daim ntawv tshaj tawm cov ntaub ntawv qhia tau hais tias cov ntawv luam tawm los ntawm cov lus piav qhia thiab cov ntaub ntawv siv tshuaj tsw qab sib xws.Source: PerkinElmer Food Safety and Quality