《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 5Downstream Processing2Downstream processing,what and why Downstream processing is any treatment of culture broth after fermentation to concentrate and purify products.Separation Processes The challengeLow product concentrationsLarge number of impurities Thermolabile bioproductsAn ideal bioseparation process should combine high throughput with high selectivity,and should ensure stability of product.Happy growingDrug producingFermentationKill the microbesSmash the microbesRemove cells/debrisConcentrate andPurify the productFormulateproductDownstream ProcessingMicrobesGenetic modificationMarketNutrientsOxygenBiological productsProductProductNature of bioseparation requiredNature of bioseparation requiredAlcoholic beverages:Alcoholic beverages:Beer,wine,spiritsClarification,distillationOrganic acids:Organic acids:Acetic acid,citric acidPrecipitation,filtration,adsorptionVitamins:Vitamins:Vitamin C,vitamin B12Precipitation,filtration,adsorptionAmino acids:Amino acids:Lysine,glycine,Precipitation,filtration,adsorptionAntibiotics:Antibiotics:PenicillinsPrecipitation,filtration,adsorptionEnzyme,Enzyme,PolysaccharidesFiltration,precipitation,centrifugation,adsorption,chromatographyDistillationSeparating components with different volatilities.Such as organic solvents,volatile flavors and aromas.Distillation Stages in Downstream Processing Removal of insolubles Product Isolation Product Purification Product Polishing 1.Cell removal(filtration,centrifugation)2.Primary isolation(adsorption,precipitation)Removing components with properties significantly different from those of the products Large volume,relatively non selective3.Purification (chromatography,ultrafiltration)Removing components with properties similar to those of the productsHighly selective 4.Product preparation(crystallization,drying)Removal of insolubles Capture of the product as a solute in a particulate-free liquid Example Separation of cells,cell debris or other particulate matter from fermentation broth containing an antibiotic.Typical Operations Filtration A mechanical operation used for the separation of solids from fluids.16Type of filtration unitPlate and frame filterRotary-drum vacuum filterCentrifugationUse of the centrifugal force for the separation of mixturesMore-dense components migrate away from the axis and less-dense components migrate towards the axis of the centrifugeCentrifugesttDecanter centrifugeProduct Isolation Reducing the volume of material to be handled and concentrating the product.PrecipitationFormation of a solid in a solution during a chemical reaction.Solid formed is called the precipitate and the liquid remaining above the solid is called the supernatant.1.Isoelectric PrecipitationGA+GA GA GA=pH 2 3.22 7.0 12 pI 2.Organic solvent precipitation By adding an organic solvent to an aqueous fermentation broth,the dielectric constant will decrease causing the solubility to decrease.ExampleXanthan gum is recovered from an aqueous fermented broth containing the gum by adding to the broth organic solvent.3.Insoluble salt precipitation Usually used in extraction of amino acid and organic acid.e.g.Citric acid extraction and purification process Heating (destroy the microorganisms)Neutralizition(forming calcium citrate)Acidifying(liberate the citric acid from its salt)Disadvantageshigh chemical costrelatively complex technology29Ion Exchange ResinsResinslOrganic or inorganic polymer used to exchange cations(positive ions)or anions(negative ions)from a solution phaseGeneral StructurelPolymer backbone not involved in bondinglFunctional group for complexing anion or cationOrganic Resin GroupsLinkage groupCation exchangeChlorideAnion exchangee.g.Purification of Lactic Acid from Fermentation Broths by Ion-Exchange Resins First,a strong cation resin was used to reduce the broth pH and remove the cations present in the solution;Then the acidified broth was purified by an anion exchanger.Membrane Separation Function:clarification and sterilization Advantages No phase change Energy efficient A higher quality product Environmentally friendly Easy to scale-up Limitations Long-term reliability not proven Excessive pretreatment Concentration polarization and membrane fouling Replacement of membranesMembrane Fraction TechnologiesUltrafiltration(2000-50,000 MW)Nanofiltration(200-700 MW)Microfiltration(100,000 MW)Reverse Osmosis(200 MW)WaterSaltsLactoseProteinMicrobes+fatSemi-permeableMembraneWine Filtration Why?Filtration Objectives/Purposes IncludeRemove insoluble contaminantsImprove clarity,brightness Extend shelf life ElectrodialysisProduct Polishing Final processing steps which end with packaging of the product in a form that is stable,easily transportable and convenient Crystallization,concentration and drying are typical unit operationsCrystallization Formation of a crystalline phase from a parent phase,e.g.solution One of the oldest and most important unit operations,e.g.extracting salt crystals from sea water Definition of Crystal A substance in which the constituent atoms,molecules,or ions are packed in a regularly ordered,repeating three-dimensional pattern.The distinction between a crystal and an amorphous solid is that between order and disorder over large distancesCrystallization ProcessLiquid MixtureGeneration of Supersaturation:Driving forceNucleation:Birth of Solid PhaseCrystal GrowthFinal ProductSupersaturation refers to a state in which the liquid(solvent)contains more dissolved solids(solute)than can ordinarily be accommodated at that temperature.Solubility&Supersolubility DiagramGeneration of supersaturationSolvent evaporationSolution coolingAltering pH Crystallization-by evaporation of saturated solutionCrystallization-by cooling saturated solution Concentration FiltrationCentrifugationReduced pressure concentration DryingDrying involves the transfer of heat to the wet material and removal of the moisture as water vapor.Usually,this must be performed in such a way as to retain the biological activity of the product.Drying MethodsAtmospheric dryingSpray dryingVacuum drying (decompression)Freeze-drying(lyophilization)lyophilizationFreezing the materialReducing the surrounding pressure and adding enough heat to allow the frozen water in the material to sublime directly from the solid phase to gas.Review Questions1.Show the importance and main procedures of the downstream processing of fermentation.State the principles and the characteristics of every separation methods.2.Tell the difference between freeze drying and vacuum drying.食品發(fā)酵工藝學(xué)綜合大實(shí)驗(yàn)時(shí)間安排食品發(fā)酵工藝學(xué)綜合大實(shí)驗(yàn)時(shí)間安排1010月月2626日（周六）日（周六）一、二班下午一、二班下午制備實(shí)驗(yàn)一、二的三種培養(yǎng)基，滅菌，倒平板，制備實(shí)驗(yàn)一、二的三種培養(yǎng)基，滅菌，倒平板，接種黑曲霉于接種黑曲霉于PDAPDA平板，接種枯草芽孢桿菌于發(fā)酵培養(yǎng)基中。平板，接種枯草芽孢桿菌于發(fā)酵培養(yǎng)基中。1010月月2828日（周一）日（周一）一班晚上一班晚上枯草芽孢桿菌離心得枯草芽孢桿菌離心得淀粉酶粗酶液。黑曲霉打孔淀粉酶粗酶液。黑曲霉打孔并接種于發(fā)酵培養(yǎng)基。并接種于發(fā)酵培養(yǎng)基。1010月月3030日（周二）日（周二）二班上午三四節(jié)二班上午三四節(jié)枯草芽孢桿菌離心得枯草芽孢桿菌離心得淀粉酶粗酶液。黑曲淀粉酶粗酶液。黑曲霉打孔并接種于發(fā)酵培養(yǎng)基。霉打孔并接種于發(fā)酵培養(yǎng)基。1111月月2 2日（周六）日（周六）一班下午一班下午黑曲霉發(fā)酵液離心得糖化液。測(cè)定糖化酶活力黑曲霉發(fā)酵液離心得糖化液。測(cè)定糖化酶活力（實(shí)驗(yàn)三）、制備淀粉水解糖（實(shí)驗(yàn)四）。（實(shí)驗(yàn)三）、制備淀粉水解糖（實(shí)驗(yàn)四）。1111月月3 3日（周日）日（周日）二班上午二班上午黑曲霉發(fā)酵液離心得糖化液。測(cè)定糖化酶活力黑曲霉發(fā)酵液離心得糖化液。測(cè)定糖化酶活力（實(shí)驗(yàn)三）、制備淀粉水解糖（實(shí)驗(yàn)四）。（實(shí)驗(yàn)三）、制備淀粉水解糖（實(shí)驗(yàn)四）。1111月月3 3日（周日）日（周日）一班下午一班下午二班下午二班下午檸檬酸的發(fā)酵與結(jié)晶（實(shí)驗(yàn)五）檸檬酸的發(fā)酵與結(jié)晶（實(shí)驗(yàn)五）。1111月月7 7日（周四）日（周四）一班下午、晚上一班下午、晚上 檸檬酸檸檬酸的紙層析的紙層析實(shí)驗(yàn)實(shí)驗(yàn)（實(shí)驗(yàn)六）（實(shí)驗(yàn)六）1111月月9 9日（周六）日（周六）二二班下午班下午檸檬酸的紙層析實(shí)驗(yàn)（實(shí)驗(yàn)六）。檸檬酸的紙層析實(shí)驗(yàn)（實(shí)驗(yàn)六）。