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Yeast Fermentation Total Time:
ALES S. cereviseae 3-4 days, 16-27 C 2-4 weeks
LAGERS S. uvarum 7-14 days, 8-18 C 3-16 weeks
Within each species of yeast exist thousands of individual strains each with their own fermentation characteristics and flavour profiles. Yeast character is extremely important, if not the most important aspect of beer flavour. Strain health is of primary importance to the modern brewer. Since they are living organisms which reproduce at a very rapid rate, most strains are susceptible to genetic changes over time (some permanent, some only transient brought on by environmental stress). Certain adverse conditions such as high nitrates in the brewing water will drastically accelerate the rate of mutations. These mutations can seriously affect a beers flavour profile, usually adversely. To overcome this problem, adept brewers employ certain techniques: washing with cold water (often acidified) to limit bacterial growth and remove dead yeast, supplementing wort with yeast food if the problem is a specific micro-nutrient deficiency stress, or regular re-propagation from pure culture to replace the active culture. This final technique, when associated with good sanitation, quality ingredients and a meticulous approach is usually sufficient.
Hops
Hops have no analogue in wine making. they are the spice of beer and provide the main source of bitterness. They look like small, soft green pine cones and are the female flower of the perennial climbing vine, Humulis lupulis. The resins and oils produced in this flower are of primary interest to brewers since they are the source of not only hop bitterness, but also, hop flavour and aroma.
Hops have been used in beer for about 30 centuries but did not come into prevalent use until the 14th or 15th century. Prior to the use of hops, beers were flavoured with herbs, roots and spices such as: juniper, coriander, cumin, nutmeg, oak leaves, lime blossoms, cloves, rosemary, gentian, chamomile and others. It seems that hop use in beer became prevalent not due to the flavour, but rather, due to the natural preservative effect of hops against bacterial spoilage.
Early use of the hop in beer, including its use in mediaeval Germany and France, seems to have been medicinal. Early naturopaths acknowledged the soothing properties of hop oils. Humulis lupulis is a member of the plant family Cannibinaceae and bears remarkable genetic similarities to Cannabis spp. We also now know that certain hop compounds increase the destruction rate of older, less efficient, red blood cells, thus invigorating the consumer as the blood is ‘cleaned’.With over one hundred commercially available varieties, hops fall into two general categories: the bittering hop - high in resins (and thus bittering power), low in oil, it is generally added early in the boil, and the aroma hop - low in resins, high in oil and generally added late in the boil and occasionally even later during the cooling process or even in the aging tank (dry hopping). Bittering hops form the base bitterness to the palate and aroma hops contribute characteristic hop flavour and aroma.
The ProcessThe process can be varied and complex, but at its heart it is elegantly simple. The brewer mills his or her grains and then mixes them with water at an appropriate temperature. The liquid thus formed, termed ‘wort’, is separated from the ‘spent’ grains via a process known as lautering. It is then boiled in the kettle where it is customarily flavoured with hops. Finally, the wort is cooled and ‘pitched’ with an appropriate yeast strain which will ferment it to beer. After the fermentation, the green beer is usually aged to stabilise and mellow the beer flavour prior to filtration (although not always), carbonation and/or nitrogenation and packaging for trade (in the case of ‘real’ ales and bottle conditioned products, carbonation is achieved in the trade package by the inclusion of fermentable sugar and live yeast).
Lagers
Bavarian (Munich or Munchener)
Early 19th century origins in Munich as dark lager.
Mildly hopped, predominant malt aroma character due to the use of Munich malt. Malt flavour dominates the palate. A pale version was introduced in 1928 known as Helles. A very popular style today.
Dortmunder
A blond or gold coloured lager introduced in the 1840’s.
It is drier than the malty Munich lagers and less hoppy and bitter than a Pilsner. It is intermediate in many ways between the aforementioned styles but its sheer balance in comparison is elegantly refreshing.
Pilsner
A general term for a pale to golden hued, highly hopped lager.
The archetypal Pilsner is Pilsner Urquell (from Plzen, in the Czech Republic). It is brewed with a very soft, almost mineral-free water.
Introduced in 1842, it was the palest beer available and the style was soon widely copied. Undoubtedly, the advent of mass production of glassware probably fuelled this worldwide general transition from dark, often murky beers to pale, brilliantly clear ones.
Vienna
- Light golden in colour with a slight redness.
- Sweet and bitter taste where neither malt nor hop predominate.
- The term is now considered synonymous with Marzen or Oktoberfest beer styles.
Bock
- Origins in the 13th century Northern Germany as an ale. It is now a dark heavy malty, strong lager available customarily in the spring. Today bocks come in many colour vari ations and strengths.
Steam Beer
- A highly hopped, highly carbonated lager fermented at temperatures more typical of an ale. Single producer: Anchor Steam Breweries (San Francisco).
Stock Ale
Strong ale, often vinous in character.
Designed for long storage.
Cream Ale
50/50 blend of ale and lager.
Also used in reference to ales conditioned in trade package.
Stout
A very dark, very heavy, very bitter ale.
7-15% roasted barley in the mash.
Porter
Dark ale, neither malt nor hop predominate, often sweet, bitter taste. Licorice is sometimes used as a flavorant and colouring agent.
Like stout, it uses large amounts of roasted malts and cereals.
Bitter/Pale Ale
- Accentuated hop character but otherwise a very wide ranging style in terms of body and colour. Archetypal Bitter was from Burton where the water is high in gypsum thus accentuating hop character in their ales.
Pale Ale Bottled Bitter.
India Pale Ale Stronger hoppier version designed to travel.
Brown Ale
Another wide ranging style.
More malty than bitter.
Not hoppy in aroma as a rule.
Barley Wines/Old Ales
Highly alcoholic ales brewed to age for long periods.
Can be very sherry-like or madeira-like. Some, but not all, are aged in wood, some times untreated wood, sometimes sherry barrels.
Bottle conditioned, filtered or unfiltered, they are designed to age and develop sometimes for more than twenty years (like Eldridge, Pope’s ‘Thomas Hardy’s Ale’.)
Scotch Ale
Ale brewed with very hard water and a long slow cool fermentation.
Usually deep amber to dark, strong, thick and heavy with pronounced hop character.
Usually contains small amounts of roast barley and amber malt.
Altbier
German ale. Unlike many of its British cousins, it is aged for longer periods.
Kolsch
Pale, light, refreshing, highly hopped, highly carbonated German ale originating in Koln (Cologne).
Berliner Weisse
A wheat beer, low in alcohol, low in bitterness which uses at least 30% malted wheat in the mash. Usually dispensed unfiltered (mit hefe).
It is intensely tart due to a secondary fermentation using certain species of the Lactic Acid Bacteria group of organisms. Because of this, it is often served with a dash of woodruff or fruit syrup.
Suddeutsches Weizenbier
Wheat beer from the south of Germany. It is higher in alcohol, fuller in body and more liberal with the use of malted wheat than its northern cousin.
Typical yeasts used to ferment this style create a marked clove-like character. Like Weisse bier, it is only mildly hopped. It does not undergo a lactic fermentation and is consequently less acidic than Weisse bier.
Lambic
Very old (1400’s) style. Extensive use of raw wheat producing milky, turbid worts boiled for three hours or more. Highly hopped but long aging periods subdue the bit terness.
Completely wild fermentation.
Very complex, often very acidic.
Geuze A blend of old and young Lambic.
Bottle conditioned. Dry to sweet.
Faro Sweetened Lambic.
Often blended young Lambic or what might be considered inferior Lambic with the best held for blending.
Sweetened with sugar, molasses, sometimes spiced or diluted with water.
Belgian Wit biers
- 50% raw wheat - 50% malted barley mash.
- Ale fermentation, sometimes spiced in the kettle with coriander and Curacao orange.
Flemish Brown Ale
- Complex blend of malts, boiling with lime, multi strain fermentations and blending makes this style very complex.
- Dry to sweet, high in acidity. Usually identifiable by an element of ‘olive-like’ bitter ness, and ‘raisiny’, ‘spicy’ notes.
Biere de Garde
- Regional specialty of the north of France.
- Amber coloured, simple mash, aged long periods in tanks before bottle conditioning in corked and wired bottles.
Belgian Red Ale
- All malt, occasionally corn to about 20%.
- Highly hopped but subdued by long aging in untreated wood.
- Multiple yeast strain fermentation.
- Often sold blended.
- Highly acidic.
- Deep red in colour.
Belgian Golden Ale
- Bottle conditioned pale ale.
- All malt and highly alcoholic.
- Elaborate triple fermentation with two distinct strains of yeast.
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