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Beer is an alcoholic beverage produced by fermentation of sugars extracted from malted barley and flavoured with hops. The manufacture of all alcoholic beverages utilises the ability of yeast to ferment sugars into alcohol. 

Beer is an alcoholic beverage produced by fermentation of sugars extracted from malted barley and flavoured with hops. The manufacture of all alcoholic beverages utilises the ability of yeast to ferment sugars into alcohol. 

Types of Beer

Lager - Biggest proportion of beer sold. Has a delicate flavour which comes from relatively under-modified and lightly kilned malt, has a relatively low bitterness, uses a bottom fermenting yeast and a cold maturation. 

Ale - Mainly made in the UK and Ireland. Flavours come from well modified and biscuity flavoured malts which are sometimes highly coloured, sometimes very bitter and uses a top fermenting yeast. Ales come in various forms bitters, pales and mild beers.

Wheat Beer - Beers produced from wheat malt instead of barley malt.

Stout - Very dark in colour, rich in flavour from highly coloured malts or roasted barley.

What is Malt?

Malt is mostly made from barley but also from other cereals like wheat and sorghum. Cereals are seeds of plants and have a store of starch and means of converting that starch into digestible food. Upon germination seeds convert starch into sugars or develop certain enzymes to do this. The malting and brewing processes exploit this so that starch is converted into simple sugars which yeast can ferment.

The Malting Process

Steeping - The seed (barley) is soaked in water to start growth.

Germination - The seed grows under controlled conditions and changes occur inside the seed.

Kilning - Malt is dried and flavours developed.

Adjuncts - Malt is sometimes supplemented with adjuncts (other sources of sugar) wheat, maize, sucrose, dextrose etc..

What are Hops?

A twining vine (Humulus lupulus) having lobed leaves and green female flowers arranged in cone like spikes. The dried ripe flowers of this plant, containing bitter resins called Alpha Acids and oils. They are used in the brewing industry to prevent bacterial action, add the characteristic bitter taste and flavours to beer.

What is Yeast? 

Yeast is a single celled micro-organism that can survive with or without air. Carbohydrates in the form of sugar are used to generate the energy it needs for survival. When no air is present it converts sugars into alcohol and CO2. Brewing yeast is selected on fermentation performance and beer flavour. Some yeasts rise to the top of the wort after fermentation is completed, these produce ales. Other yeasts fall to the bottom of the brew, these produce Lagers.

The Fermentation Process

 During fermentation yeast converts sugar into alcohol. Yeast population grows by about 5x during the fermentation process.There are four stages in brewery fermentation. 

  1. Yeast cells rest.
  2. Yeast cells start multiplying.
  3. Yeast ferments sugar into alcohol.
  4. All the sugar has been converted and the yeast separates from the beer. 

Beer Maturation 

After fermentation beer is not ready to drink in contains ‘green’ flavours and needs to mature before packaging. Beer is matured in tanks or casks, during this time yeast absorbs or modifies unpleasant flavours, settles out and the beer clarifies. At low temperatures beer stabilises preventing haze formation. At home beer is often matured in bottles where yeast produces more CO2 to carbonate the beer.

Beer Filtration 

When beer is bottled or cask conditioned it does not need to be filtered. When bright, clear beer is required it is filtered. Filters work by a combination of sieving out the beer particles, trapping particles in a complex pathway of a filter bed and absorbing particles on a filter aid.

Packaging Beer

Beer is packaged to provide consumers beer in a convenient package and to ensure quality is protected. Packages include bottles, cans, kegs and casks. Beer must be protected during packaging, contamination must be avoided especially from air or micro-organisms. Microbiological stabilisation is done by pasteurisation or sterile filtration. Non-biological stabilisation is done by polish filtration and the addition of a preservative. 

 

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