《食品發(fā)酵工藝》英文課件PPT,食品發(fā)酵工藝,食品,發(fā)酵,工藝,英文,課件,PPT Chapter 2 Preparation of Culture Medium Unit 1 Industrial Fermentation Medium The basic ingredients of media include carbon source、nitrogen source、inorganic salt、growth factor and distilled water etc.MediumDevelopmentnTo maintain economic competitiveness,low-cost crude materials are frequently usednLevels of minerals and growth factors may be criticalKinds of Culture MediaThe source of media constituent ComplexmediaSyntheticordefinedmediaSemi-definedmediumPhysics statesLiquidmediumSolidmediumSemi-solidmediumFor useBasicmediumEnrichedmediumDifferentialmediumSelectivemediumManufacture intentionSeedmediumFermentmediumNutrient sources for industrial fermentationCarbon&energysource+nitrogensource+O2+otherrequirementsBiomass+Product+byproducts+CO2+H2O+heatNutrientRaw materialCarbonmolasses,starchNitrogencornsteepliquor,soybeanmeal,pureammoniaorammoniumsalts,urea,nitratesalts,phosphatesaltsVitaminsandgrowthfactorsbiotin,yeastextract,beefextract,cornsteepliquor,wheatgermmealFermentationmedia1.Carbon sources (1)Starch(corn,wheat,potato)Widely used in fermentation industryStarch dextrin glucose Advantages:cheaper than glucose(2)MolassesByproduct of cane or beet sugar productionA dark viscous syrup containing 50%-75%fermentable sugars(mainly sucrose)with 2%nitrogen,vitamins and mineralsCheaper 2.Nitrogen source (1)Inorganic nitrogen source Ammonia,ammonium and nitrate Microbes can utilize it faster.After it is utilized,the pH of medium will be changed.(NH4)2SO4 2NH3+H2SO4 NaNO3+4H2 NH3+2H2O+NaOH(2)(2)Organic nitrogen sourcesUreaYeast extractPeptonesCorn steep liquorSoybean cake powder Peanut powderBran hydrolysis liquidcornsteepliquorpowder3.Trace elements Fe,Mn,B,Zn,Cl,Mo,Cu4.Growth factors Small amount of organic compounds necessary for microbial growth.e.g.amino acids,vitamins,biotin Sources:normally organic nitrogen source e.g.corn steep liquor Corn steep Liquor,CSLnCorn steep liquor is the water extract by-product resulting from the steeping of corn during the commercial production of corn starch and other corn products.Different medium for different food productsChinesedistilledspirit：solidmediumFruitspirit：fruitjuiceorfruitsauceBeer：wortAlcohol:starchmashAminoacid:starchmashCitricacid：starchmashLacticacid：starchmash Unit 2 Preparation of Starch Sugar Starchisalargemoleculethatismadeofbranchingchainsofglucosemolecules.Itcanbebrokendownintoglucosebyhydrolysis.nStarchfoundingrains,potatoes,beans,peas,cassavanTypically20-30%amylose,remainderamylopectinCharacteristicsofstarchInsolubleinhotwaterBluecomplexcompoundbyreactionwithiodine.Insolublein30%ofethanolsolutionorabove.Hydrolyzedbyacidandenzyme,theultimateproductisglucose.starch granuleIV.A.ii.-20Starch:AmylosenAmyloseisalinearglucanwith1,4glycosidiclinkagesIV.A.ii.-21Starch:AmylopectinnAmylopectinisabranchedglucanwith1,4and1,6glycosidiclinkagesStarch:Amylopectinnlessextended(morecompact)thanamylosenlargerMW 1,6 linkages 1,6 branch points result in tree-like structureWhy should starch be hydrolyzed to glucose?1.Mostmicrobescouldnotutilizestarchdirectly.2.Toobtainsugarfromthestarchofmanydifferentplants,ratherthanjustsugarbeetsorsugarcane.Conversion of starch to fermentable sugars 1.Acid hydrolysis method Starch slurry is acidified to a pH value and then heated in a converter under pressure.(C(C6 6H H1010O O5 5)n n (C(C6 6H H1010O O5 5)x x C C1212H H2222O O11 11 CC6 6H H1212O O6 6 amylumdextrinoligosaccharidesglucoseDue to heat and acid,there are Glucose combination reaction combination reaction and and decomposition reactiondecomposition reactionstarch glucose oligosaccharidecolourcontent(difficult to utilize)(difficult to decolor)Total lost of glucose 7 7 1shortening the starch(Liquefaction)glucoamylase-produces glucose(saccharification)glucose isomerase-convert to fructose(isomerization)3.Acid-enzymecombinationmethod(Two-stagehydrolysis)Slurryisonlypartiallyconvertedbyacidandthentreatedwithanappropriateenzymeorenzymesuntiltheconversioniscomplete.1)Acid-enzyme hydrolysisAcid-liquefactionGlucoamylase-saccharificationSuitable for:starchgranuleishard2)Enzyme-acid hydrolysis-Amylase(thermostable)-liquefactionAcid-saccharificationSuitable for:starchgranulesizeisirregularProduction of Glucose from StarchItemsItemsacidacidacid/enzymeacid/enzymeenzymeenzymeDEDE valuevalue919195959898ColorColor10100.30.30.20.2Processingcondition HTPHTPNTPEnergy consumingEnergy consuminghighhighhighhighlowlowBy-productBy-productmoremoremoderatemoderatelittlelittleCycle time Cycle time shortshortmoderatemoderatelonglongReview Questions1.Whichkindofcarbonsourceandnitrogensourceusuallyusedinindustry?Citetheadvantagesanddisadvantagesofthedifferentchoices.2.Whatisthedefinitionofgrowthfactoranditsmainsource?3.Whatisthesignificanceofgettingsugarbyhydrolyzingstarch?4.Comparethethreemethodstoproduceglucosefromstarchandthedifferencebetween combinationreactionanddecompositionreaction,liquefactionandsaccharification.InductionRepression1.Itturnstheoperonon.1.Itturnstheoperonoff.2.Itstartstranscriptionandtranslation.2.Itstopstranscriptionandtranslation.3.Itiscausedbyanewsubstance,whichneedsenzymestogetused.3.Itiscausedbyanexcessofexistingmetabolite.4.Itoperatesinacatabolicpathway.4.Itoperatesinananabolicpathway.5.Repressorispreventedbytheinducerfromjoiningtheoperatorgene.5.Repressorisenabledbyaco-repressortojointheoperatorgene.Feedback repressionFeedback inhibitionRegulationlevelgenetic:RNAtranscriptioncellular:activityofenzymeComplexformedendproduct+repressorendproduct+enzymeEffectoperatoronDNAtemplateoccupiedbythecomplexreducedenzymeactivityConsequenceblockedtranscriptionTherespectivereactionisinhibited.