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Lecture Outline

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Lecture 13 - Basic beer making
 

Objectives

•      List changes in beer making throughout history

•      Outline steps in modern beer making

•      Describe changes in beer quality as a function of processing changes

Early beer making

•     Considered the ancestor of lambics

•     Sumerians: 1^st written references; 20 recipes for beer, Sikaru was a ceremonial beer

•     Babylonians had commercial brewery in city of Ur 2000 BC

•     Ancient beer is more different from modern beer than ancient wine is from modern

•     Beer making was local; Major breweries with wide distribution is modern phenomenon

•      New trend toward microbreweries and home-brewing (legal since 1978)

•   Brewing tends to flourish in grain growing areas

Rheinheitsgebot : German "Pure beer" law

–   Beer could be only barley malt, hops and water (with exception for wheat beer)

–   Did not know about yeast

•      E.C. overruled Reinheitsgebot but most German brewers still adhere to the law

•      Early beer makers often added herbs, spices and honey

Basic steps beer-making: Grain harvest, Malting grain, Brewing, Fermenting, Finishing

Malting - Yeast can only convert sugar to alcohol

•      Malting is the process of converting starch to sugar by allowing the grain to sprout, then roasting the grain to stop the process and maximize sugar level

•      Malting was invented by the Egyptians; Early beer makers used other methods

Malting process

•      Grain soaked in water and drained several times

•      Spread on big floors: Germinates in 5 days, Stirred regularly

•      Enzymes produced during germination

–   Proteases - break apart the protein holding the starch granules

–   Amylases - convert starch to sugars

•      When sprouts are ¾ of seed length, grain is baked in an oven to dry: Crisp, chewable

–   Longer times and higher T° à darker, more flavorful malt

–   Same ingredient used in making malt whiskey and various cereals

Brewing process

Mashing - malt mixed with hot water (60°C)

–  Hydrates starch; Allows amylase to convert starch to sugars (maltose and dextrin, collectively called wort and pronounced "wert")

Lauter - strain wort from spent grain (used for cattle feed, incorporated into bread, etc)

–   Sparging: rinse w/ boiling water, recover all wort possible

Kettle boil

–   Sterilizes wort before fermentation

–   Precipitates unwanted proteins

–   Add hops several times while boiling

Fermentation

•   Cool and strain out spent hops and precipitated proteins

•   Add desired yeast (called pitching)

–   Ale - top fermenting yeast (S. cerevisiae)

–   Lager - bottom fermenting (S. carlsbergensis = S. uvarum)

•   Aerobic phase where the yeast multiples and conditions followed by Anaerobic phase where alcohol is produced

•  Mature several days at cool T° - Allows flavor development & Facilitates clarification

–   Ale: 6-8 days; Lager: 14-21 days

Finishing

•      Remove protein haze and yeast by (light) filtration

•      Carbonation

–   In bottle: bottle conditioned (bottled without removing yeast)

–   In tank (Krausen): small dosage of wort added to the conditioning tank, then conventionally filtered

–   In line: like soft drinks

•      Filtration makes beer clear, but not microbially safe

–   Cold filtration through small pore membranes to avoid pasteurization

–   Pasteurize if not cold filtered

•      Package (bottle, can, keg)

Styles of malt

•  Pale malt: most common, used in both light ales & lagers

–  Kilned 48 hours with slowly rising temperature

•  Amber and brown malts: less often used today

–  Heated at higher temperature to give more coppery color

•  Crystal malt: Rapidly rising temperature dries out husk

–  Hard, sugary, crystalline core; gives fuller, sweeter flavor

•  Chocolate malt: steadily heated to 400°F

–  Has dark color and complex flavor

•  Black malt: Chocolate malt taken to just short of burning

–  Used in stout, porter sparingly. Bitter, smoky flavor

Types of hops

•      Good King Wenceslas killed those taking hops cuttings out of Bohemia

•      Varieties have differing amounts of flavor compounds

–   Alpha acids -

•   Most desired bittering agents (Measured in bittering units- IBUs)

•   Known collectively as humulus, has 3 different chemical forms

–  Air oxidized hops don’t have much a acid flavor

•     Beta acids - Known collectively as lupulus, are less desirable

•      Other secondary compounds add complex flavors

Types of Hops

•      About 20 varieties of high alpha acid hops are in common use

•      Many countries with colder climates have good hops

•      Common high a acids ones are:

–   Admiral (UK), Centennial (US), Cascade (US), Magnum (Germany)