牛奶和其他 食品的技术应用.docx

牛奶和其他 食品的技术应用.docx

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牛奶和其他食品的技术应用

AdjunctCultures:

RecentDevelopmentsandPotentialSignificancetotheCheese

Industry

1

Thisarticleisnotincludedinyourorganization'ssubscription.However,youmaybeabletoaccessthisarticleunderyourorganization'sagreementwithElsevier.

M.ElSoda†,S.A.Madkor*andP.S.Tong*,

*DairyProductsTechnologyCenter,CaliforniaPolytechnicStateUniversity,SanLuisObispo,California93407

†DepartmentofDairyScienceandTechnology,FacultyofAgriculture,AlexandriaUniversityAlexandria,Egypt

Received6July1999; 

accepted16November1999. 

Availableonline3April2010.

Abstract

Severalpreviousreviewshavedescribeddifferentwaystoenhancetheflavorandtextureofcheese,includinguseoflivecellsandnonviableattenuatedcellsasadjunct

cultures.

However,comparisonsbetweenviableandnonviable

cultures

wereneverdiscussedinthesereviews.Inaddition,recentpublicationsonadjunct

cultures

havenotbeencoveredinpreviousreviews.Thisarticlewillsurveythemorerecentworkonadjunct

cultures

—withparticularattentiontowhethertheadjunctscontainedviableornonviablecells—andproposeareaswhereadditionalresearchisneeded.

Keywords:

adjunctlactobacilli;attenuation;autolysis;cheeseripening

Abbreviations:

LAB,lacticacidbacteria;NSLAB,nonstarterlacticacidbacteria

Correspondingauthor.

1 PartofthisreviewwaspresentedbyMorsiElSoda,recipientofthe1998MarschallRhodiaInternationalDairyScienceAwardatthe93rdADSAmeeting,Denver,Colorado.

JournalofDairyScience

Volume83,Issue4,April2000,Pages609-619

Anovelreal-timepolymerasechainreaction-basedmethodforthedetectionandquantificationoflactose-fermentingEnterobacteriaceaeinthedairyandotherfoodindustries

Thisarticleisnotincludedinyourorganization'ssubscription.However,youmaybeabletoaccessthisarticleunderyourorganization'sagreementwithElsevier.

M.C.Martín1,a,N.Martínez1,a,B.delRioa,V.Laderoa,M.FernándezaandM.A.Alvarez

a,

aInstitutodeProductosLácteosdeAsturias,CSIC,33300Villaviciosa,Asturias,Spain

Received12June2009; 

accepted25November2009. 

Availableonline19February2010.

Abstract

Thepresenceoflactose-fermentingEnterobacteriaceaeandcoliformsisroutinelyassessedtodeterminethehygienicqualityofwaterandfoods,particularlydairyproducts.ThispaperreportstheuseoflacZ-specificprimersinanSYBRgreenI-basedreal-timePCRmethodfortheeasyandrapiddetectionofcoliformsindairyproducts.Alargenumberofbacterialspecieswereassayedtoestablishthespecificityofthemethod.Thesensitivityofthemethodwasassessedusingartificiallycontaminatedcheeses.Thelimitofdetectionwas1coliformcellincheesesamplesenrichedfor8 hina

culture

medium.Theentireprocedure,includingsampleprocessing,enrichment,DNAextraction,andreal-timePCRamplification,canbecompletedwithin10to12 h,makingitasingle-dayassay.

Keywords:

Enterobacteriaceae;coliform;real-timepolymerasechainreactiondetection;cheese

ArticleOutline

Introduction

MaterialsandMethods

BacterialStrains

ExtractionofDNAfortheRT-qPCRAssay

lacZSequencingandNucleotideSequenceAnalysis

RT-qPCRConditions

DataAnalysis

ArtificialContaminationandEnrichmentofCheese

NucleotideSequenceAccessionNumbers

Results

SequencingofthelacZGenesandPrimerDesign

OptimizationofRT-qPCR

SpecificityandSensitivity

MeltingCurveAnalysisoftheAmplifiedDNA

RT-qPCRDetectionLimits

Discussion

Acknowledgements

References

Figure1. Alignmentofa63-bpregionoftheβ-galactosidase（lacZ）genefrom22representativecoliformstrains（Citrobacterfreundii,Escherichiacoli,Enterobactercloacae,Klebsiellapneumoniae,Enterobactersakazakii,Citrobacterkoseri,Citrobacteramalonaticus,andRaoultellaplanticola）usingClustalWsoftware（Altschuletal.,1997）.Thelocationsoftheprimersareshownbyarrows,anasteriskdenotesidenticalsequences,andadashindicatesamismatchwiththeconsensussequence.

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Figure2. Standardcurvesforthelognumberofcoliformcellsperreactionversusthecyclethreshold（Ct）valueforthefluorescentsignalforA）EscherichiacoliCECT515,B）EnterobactercloacaeCECT194,C）CitrobacterfreundiiCECT401,andD）Klebsiellapneumoniaessp.pneumoniaeCECT143.Theerrorbarsindicatestandarddeviationsfor3independentexperiments.CECT = ColecciónEspañoladeCultivosTipo,Burjasot,Valencia,Spain.

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Table1.

Strainsusedinthiswork

1 CECT = ColecciónEspañoladeCultivosTipo,Burjasot,Valencia,Spain;LSP = LaboratoriodeSaludPública,PrincipadodeAsturias,Spain;CNRZ = CentreNationaldeRecherchéZootechniques,Jouyen-Josas,France;LMD = LaboratoryofMicrobiology,TechnicalUniversity,Delft,theNetherlands;ATCC = AmericanTypeCultureCollection,Rockville,Maryland.

2 RT-qPCR = real-timequantitativePCR; + indicatesapositiveRT-PCRresult,–indicatesanegativeresult.

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Table2.

Detectionofcoliformsincheesebycultureenrichmentandreal-timequantitativePCR1

1 CECT = ColecciónEspañoladeCultivosTipo,Burjasot,Valencia,Spain;1,10,and100indicatethecontaminationlevelofcoliforms（cfu/mL）beforeenrichment; + indicatesapositiveRT-PCRresult,–indicatesanegativeresult.

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Correspondingauthor.

1 Theseauthorscontributedequallytothiswork.

JournalofDairyScience

Volume93,Issue3,March2010,Pages860-867

Biochemistry,Genetics,andApplicationsofExopolysaccharideProductioninStreptococcusthermophilus:

AReview1

Thisarticleisnotincludedinyourorganization'ssubscription.However,youmaybeabletoaccessthisarticleunderyourorganization'sagreementwithElsevier.

J.R.Broadbent*,†,

D.J.McMahon*,†,D.L.Welker*,‡,C.J.Oberg*,§andS.Moineau||

*WesternDairyCenter,DepartmentofUtahStateUniversity,Logan84322-8700

†NutritionandFoodSciencesandDepartmentofUtahStateUniversity,Logan84322-8700

‡BiologyUtahStateUniversity,Logan84322-8700

§DepartmentofMicrobiology,WeberStateUniversity,OgdenUT84408-2506

||DépartementdeBiochimieetdeMicrobiologieUniversitéLaval,Québec,Canada,G1K7P4

Received10May2002; 

accepted25June2002. 

Availableonline27March2010.

Abstract

ManystrainsofStreptococcusthermophilussynthesizeextracellularpolysaccharides.Thesemoleculesmaybeproducedascapsulesthataretightlyassociatedwiththecell,ortheymaybeliberatedintothemediumasalooseslime（i.e.,“ropy”polysaccharide）.AlthoughthepresenceofexopolysaccharidedoesnotconferanyobviousadvantagetogrowthorsurvivalofS.thermophilusinmilk,insituproductionbythisspeciesorotherdairylacticacidbacteriatypicallyimpartsadesirable“ropy”orviscoustexturetofermentedmilkproducts.Recentworkhasalsoshownthatexopolysaccharide-producingS.thermophiluscanenhancethefunctionalpropertiesofMozzarellacheese,buttheyarenotphage-proof.Asourunderstandingofthegenetics,physiology,andfunctionalityofbacterialexopolysaccharidescontinuestoimprove,novelapplicationsforpolysaccharidesandpolysaccharide-producingcultures

arelikelytoemergeinsideandoutsidethedairy

industry.

Thisarticleprovidesanoverviewofbiochemistry,genetics,andapplicationsofexopolysaccharideproductioninS.thermophilus.

Keywords:

Streptococcusthermophilus;exopolysaccharide;lacticacidbacteria

Abbreviations:

CPS,capsularexopolysaccharide;CPS+/−,ability（+）orinability（−）toproducecapsularexopolysaccharide;EPS,exopolysaccharide;EPS+/−,ability（+）orinability（−）toproducecapsularorsecretedexopolysaccharide;LAB,lacticacidbacteria

ArticleOutline

Introduction

HeteropolysaccharideStructureandBiosynthesis

GeneticsofEPSProductioninS.thermophilus

PhysiologicalRoleofEPS

BacteriophageResistance

ApplicationsinYogurtandFermentedMilks

ApplicationinMozzarellaCheese

Conclusions

Acknowledgements

References

Figure1. BasicrepeatingstructuresofStreptococcusthermophilusextracellularheteropolysaccharides.Fuc,fucose;Gal,galactose;GalNAc,N-acetyl-D-galactosamine;Glc,glucose;Rha,rhamnose;Ac,O-acetylgroup;p,pyranoseconfiguration;andf,furanoseconfiguration.

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Figure2. ModelforassemblyoftheStreptococcusthermophilusSfi6exopolysaccharidebasicrepeatingunit.Gal,galactose;GalNAc,N-acetyl-D-galactosamine;Glc,glucose;UDP,uridine-diphosphate.AdaptedfromStingeleetal.（1996,1999）.

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Figure3. PhysicalmapsofthegeneticregionsassociatedwithexopolysaccharidebiosynthesisinStreptococcusthermophilus.Boldlettersidentifystrainnames,andfillpatternsidentifygenesthatareatleast90%identicalamongstrains.Putativeorestablishedfunctionsforindividualgeneproductsarelistedundereachcluster.GTF,glycosyltransferase;MTr,membranetranslocation;Pol,polymerization;Reg,regulation;SB,sugarbiosynthesis;Unk,unknown.Mapsarenottoscale.1StrainCNRZ368doesnotproduceexopolysaccharidedue,presumably,tomutationsinseveralcpsgenes（Bourgoinetal.,1999;Broadbentetal.,2001）.2Sequencedataforthe3′regionoftheSfi6epsclusterdoesnotextendbeyondorf14.9（Stingeleetal.,1996）.3Sequencedataforthe3′regionoftheSfi39epsclusterdoesnotextendbeyondorf14.9（Germondetal.,2001）.4Sequencedataforthe3′regionoftheFI9186epsclusterdoesnotextendbeyondepsG（I’Anson,2002）.

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