Introduction and MicrobialProduction of Beer Prepared by: Othima Sharma M.Sc. Biotechnology 2nd Semester Roll: 301101023
HistoryChemical analysis of 7,000 year-old jugs putsinvention of beer around the same time periodas wineAddition of hops to beer occurred about onethousand years ago but before the 14th centuryspruce, ginger, wormwood, sage, and sweetmary were more popular.1516 Bavarian purity law passed, oldestknown food purity law still in effect, limitedingredients of beer to hops, barley, and water.16th century lager beer type accidentallyinvented during cold cave fermentation.
Essential Ingredients of Beer• Malted Barley• Hops• Yeast• Water• Not required, but frequently found ingredient − Starch adjuncts • Corn and rice starches
YeastIt is usual to select strains of yeast for brewing from yeasts already in commercial use.Some breweries isolate, select and maintain their yeast strains but others engage specialist laboratories to provide this service.
Yeast can be found naturally on the surface ofmost plants including barley seeds. “Wild” yeast will most likely produce flavors that are undesirable.During the fermentation process, undesirablemicrobes must be kept out of the beer.Saccharomyces cervisiae is the species most often used for ales, its optimumfermentation temperature is 16-24 CSaccharomyces uvarium is largely used in lagers, and steam beers. Theoptimum temperature for this fermentation is 2-13 COver a 15 square mile area near Brussels the resident wildyeast and bacterial populations are perfect for spontaneouslyfermenting, beer. This fruity sour beer is known as a “lambic”.
What qualities should my yeast have?Rapid initiation of fermentationHigh fermentation efficiencyHigh ethanol toleranceDesired flavor characteristicsHigh genetic stabilityRange of alcohol production
Yeast InoculumIn the average brewery, a large inoculum of cells is used (ca 5-15 million cells/ml of wort).In each fermentation the cell density increases three-to- four-fold.Therefore, one-third
Metabolism Major Reaction: Glucose to Carbon Dioxide and EthanolSpecial flavors and aromas of beers arise from minor biochemical reactions
Malt Malt is one of the main ingredients and is obtained from barley, which is subjected to a process of germination under controlled conditions. This operation (called malting) causes, towards the end ofthe production process, the development of carbohydrates and nitrogenous substances bythe enzymes formed during
Other unmalted cereals Of the unmalted cereals normally used, corn is very common; the oils are extracted, then it is milled and called grits. Barley, rice or wheat may also be used. These cereals are used to reduce the percentage of proteins
Humulus lupulus (hops)
Hops are the flowering portion of the hop vine. These flowers not only fight off bacterial infections in the beer, they aid in clarification of the beer, stabilize theHop oils are produced in the Lupulin flavor, help retain head, and aid in onesglands of the flower. ability to drink the beer.The oils are made of α and β-acids, butα-acids contributes more to the bitteringof a beer.These oils are non-polar, and can onlybe extracted through a short boiling.
Hops (humulus lupulos): Why it is Used?? The hop (humulus lupulos) is an aromatic plant that gives beer its flavour and bitterness. It contributes to theformation of a good froth and protects the beeragainst contamination by microorganisms. Today, extracts from this plant are used industrially,
Wort• What’s in it: −Brewers wort (145) commonly has 8-14% total solids. −90-92% are carbohydrates: glucose, fructose, maltose, sucrose, malto triose. −Nitrogenous compounds, such as, amino acids. −Vitamins: biotin, inositol, pantothenic
Preparing the Wort The first phase in the process ofbeer production is the preparation of the wort.
Milling MashingFiltration of the wortBoiling the wort
Milling: Mashing: The flour from theIn orderfor the cereals (malt and othermalt unmalted cereals) is mixedcompone with water and subjected tonts to berapidly certain processes to obtain aextracted wort of a suitable compositionandconverted for the kind of beer being, the malt produced (varyingis milled times, temperatures and PH).to obtaincoarse These conditions encourageflour. The the development of complexotherunmalted starch molecules and proteins
Filtration of the wort: After mashing, thewhole volume is filtered in order to separate the spent grains (which is an excellent animal feed) from the wort itself. This isdone by passing water through the mash at the right temperature in a filter press or lauter tun, which lasts around 2-3 hours, conducted at a temperature of 75-80 ºC.
Boiling the wort: The diluted and filtered wort is boiled for around 2 hours. Hops are added at this stage. The purpose of boiling is to: Transform and make soluble the bitter substances in the hops; Eliminate undesirable volatile substances; Sterilise the wort; Provoke the precipitation of proteins of high molecular weight; Establish the final concentration of wort.After boiling, it is necessary to separate the
Fermentation/Maturation/StabilisationDuring fermentation, the wort sugars areconverted by the transformation of yeast intoalcohol and carbon dioxide. Fermentationbegins when yeast of a culture selected for thetype of beer being produced is added to thecooled oxygen-saturated wort.Fermentation takes place at controlled
Maturation, The next the phase after operation is fermentation, is stabilisati the period in on. Thiswhich the beer is consists of allowed to rest letting the at suitable beer temperatures in stabilise at order for the temperatur undesirable es of
Clarification of the Beer Clarification is the operation that gives the beer its clear limpid quality, eliminating the last remaining traces of clouding still in suspension. It consists of pumping the liquid
BottlingThe final stage of the beer productionprocess is transferring the beer intodifferent kinds of containers(bottles, barrels, cans etc).Before or after bottling, the beer needs tobe biologically stabilised. This operationmay be carried out cold (sterilisingfiltration) or hot (usingpasteurisation, which may be done either
BeerProduction Process:At A Glance
Process Malted Barley and Specialty GrainsMalted barley and specialty grains are runthrough roller mill and cracked open.This grist is then carried by an auger to the
ProcessIn the mash tun the grist is mixed with hot water toform a mash.In the mash, enzymes that exist in the grain becomeactive and convert the starches to fermentable sugar.The sugar rich liquid from the mash, called wort, is
ProcessThe wort is drained from the mash tun andmoved to the brew kettle.In the brew kettle the wort is boiled and hopsare added.
ProcessAfter boiling, the wort is transferred through achiller.While passing through the chiller the wort isinstantly chilled to the appropriate temperature
ProcessFrom the chiller, the wort moves into atemperature controlled fermenter.Yeast is added and fermentation begins. Infermentation the yeast will ferment sugars in the
Saccharomyces cervisiae Saccharomyces uvarium Location of fermentation Top Bottom Risk of infection High Low Fermentation Time Short Long Metabolizes Ethanol, Sugars Glyceraldehyde, Melibiose, SugarsFermentation Temperature 16-22 C 8-16 C
Fermentation Systems• Cylindroconical systems: −Produce ales and lagers. −Conical base, and pressure systems. • Open systems: −Used for the fermentation of ales −Utilize skiming for repitching −Carbon dioxide can
Types of Beer(on the basis of fermentation conditions) Ales & Lagers
Fermentation of AlesTop fermenting-rise to the surface and create a think yeasty head.Warmer temps- 60-70FMore rapid growthCreate more estersComplex and FruityAles, porters, stouts, and wheat beers.
Fermentation of AlesLag phase is when yeast is building cell walls and reserves.Then yeast begin to divide.First visible sign of fermentation is bubbles starting to form, which spread until the surface is covered.After 18 hours the bubbles thicken and change to a light brown color.pH and specific gravity fall, and temperature and yeast count rise.Max fermentation is reached after 36-48 hrs.White yeast head on top, with CO2
Fermentation of LagerBottom fermenting-yeast settle to the bottom of the fermenter as fermentation reaches completion.Colder tempeatures: 47-58FSlower growthCrisp and hoppy like a pilsner or sweet and malty like a Dopplebock.Examples: Pilsners, Bocks,
Fermentation of LagerTime-temperature profiles vary widely.Pitch the yeast at 5-60 C and raise to 8- 90 C. This makes better beer because the low temps retard the development of by-products which are inappropriate in lager (esters, fusel alcohols, diacetyl).Lag period is longer at lower temperatures though.After primary fermentation the temperature is dropped by 1-1.5C each
Compounds produced in primary fermentation and not reduced during lagering• Fuel or higher alcohols: By-product of amino acid metabolism. Levels are affected by yeast strain. Spicy, wine-like, and alcoholic taste.• Organic acids: Formed from carbohydrate metabolism Contribute to the sourness or acid taste (also pH) of beer.
Esters: By-product of lipid metabolism in a reaction between an alcohol and intermediates of lipid synthesis. Acetate esters Fatty acid Usually impart a fruity character to the beer. ester There areethyl acetate ethyl two types: (solventy, caproateAle yeast strains sweet) fruity, (apple, isoamyl aniseed, produce acetate sweet)more esters
Compounds produced in primary fermentation and reduced during lagering• Diacetyl Byproduct of amino acid metabolism. Tastes like butter, butterscotch, and feels slick on the palate.• Pentadione Similar to diacetyl. Milder flavor similar to honey or butter.
Acetaldehyde Intermediate of ethanol production. It can form in autolysis of yeast during lagering if yeast is in poor condition. It can also form if post-fermentation beer is exposed to air (oxygen). Ethanol can be oxidized to acetaldehyde.Acetoin Formed from a secondary reaction of alcoholic fermentation. Pyruvate decarboxylase converts pyruvate to acetaldehyde, which is then converted to
ProcessAfter fermentation the fermented wort, now called beer, istransferred through a filter.The filter removes various proteins, hop residue and yeast cells.
ProcessFrom the filter, the beer moves to the beer servers.These are carbonating tanks, holding tanks and serving tanks.
Making Beer: a three step process Malting BrewingFermentation
Malting• Takes place in malt houses − Occasionally in a brewery (Coors)• Controlled germination of barley − Moisture − Temperature − Carbon dioxide• Goal − Produce enzymes useful for brewing • Amylases • proteases
Malting• Soaking the grain• Allow for controlled germination − Maximum enzyme production − Minimum enzymatic activity and plant growth• Kiln drying − Stop germination − Stabilize malted barley − Impart color and flavor • Light malt, dark
Brewing• Functions: − Enzymatic conversion of starch to maltose, proteins to amino acids − Extraction of hop flavors and aromatic compounds − Sterilize maltose/aa/hop flavor solution
Brewing• Milling of malted barley − Careful cracking of malted barley • Shatter endosperm • Keep husk in large pieces• Adding water• Controlled temperature for enzymatic action
Mash TunThe mash tun is a vessel in which the milled maltedbarley is mixed with water And the enzymes areallowed to degrade the starches and proteins into
MashThese photos show the milledMalted barley being mixed withWarm water. The enzymesConvert the starch to maltose andThe proteins to amino acids creatingWhat is known as sweet wort.
Lautering(filtering) The sweet wort Is separted from The spent barley By a filtration step Known as Lautering. The Barley husks serve As the primary Filtering material. Here, the remaining Spent grains are Being removed from The sweet wort With this screen.
Mash Tun with usedMash These are the spent malt that acted as a filtering bed for the sweet wort.
Fermentation Tanks After the yeast is added to the hopped wort, fermentation of the maltose to Ethanol occurs in these tanks.
Adding yeast to thefermenter
fermentation tanksFermentation producesboth ethanol and carbondioxide. Thecarbondioxide isallowed to vent outthrough these blow-offhoses whose ends areimmersed in a tank ofwater, producing an air-lock and preventingOxygen from enteringthe fermentation tanks.
Cleaning fermentationtanks Cleanliness is critical in producing Quality beer. Microbial contamination Can result in off flavors and aromas.
Raw Materials Preparation Transformation Mashing Barley Water Filtration Boiling Hops Cooling Carbon Dioxide Fermentation and Yeast Yeast Maturation Bottling Clarification
Mill FermentationMashing ClarificationFiltration BottlingWort Boiling Wort Production