Recognition

Tastes and smells like unripe green apples. Beer may have the smell and taste of cider. Acetaldehyde is detectable above 175 mg/l. At its extreme it tastes like vinegar (Acetic Acid).

Formation

The second and more common cause is the oxidation of alcohol to acetic acid, either by through exposure to the air or acetic acid produced by bacterial infection (acetobacter). The flavour is vinegary and less pleasant.

Examples

Budweiser, the US beer, is deliberately brewed to give 6-8 ppm acetaldehyde.

Recognition

Alcohol can be recognised by its aroma and effect in the mouth. It creates a hot, spicy sensation in the nose and has a vinous aroma. In the mouth and throat it gives a warm, prickling sensation.

Formation

The amount and type of alcohols produced depend on the sugars (fermentables) in the wort, the yeast strain, its attenuation characteristics (how well it can convert sugar to alcohol) and the fermentation temperature.

Examples

Thomas Hardy's ale has a high level of fusel alcohols and a distinctive vinous taste. Pilsners generally have low levels.

Recognition

Astringency is not an aroma or taste but a mouth-feel. It is sensed through the stimulation of the nerves throughout the mouth. It causes an easily recognisable puckering of the mouth and a feeling of dryness. At its extreme it is very unpleasant. The sensation is reminiscent of chewing unripe grape skins.

Formation

The most common cause is poor cleaning of brewing equipment, excessive hop rates or excessive wort attenuation were the lack of residual sugars give a greater perception of astringency. Other causes include, alkaline mash or runoff water; excessive sulphate, magnesium, iron or acidity; over crushing of the grain, boiling the grains, too high a lauter run-off temperature and leaving the beer too long on the trub.  

Examples

Young wine is a good example of an over astringent drink.

Recognition

Bitterness is one of the four basic tastes. The receptors are located at the back of the tongue and over the roof of the mouth.

Formation

Bitterness is measured in IBUs (International Bitterness Units). A beer with a high value of say 40 may not taste bitter if it has been balanced by the sweetness of the malt.

Examples

Beers such as Oakham JHB or De Ranke XX Bitter have a high bitterness. Some beers may have a greater level of bitterness but this is balanced by the sweetness of the malt. Traditional English milds are low in bitterness.

Recognition

Body is the feeling of viscosity in the mouth. Beer may feel light and thin or full and heavy. Sometimes a very full-bodied beer is described as chewy.

Formation

The level of residual sugars and dextrins in beer give it its body. These are the components that the yeast is unable to ferment. Body is a desirable characteristic of many beers. It is created by the use of crystal malt and brewing sugars. A high temperature (saccharification) rest in the mashing process also increases the level of un-fermentable sugars.

Examples

 Strong, extra and export bitters (over 4.6%) will mainly have lots of body.

Recognition

Carbon dioxide (CO2) dissolved in beer gives it its sparkle or more rightly its condition. This carbonation can be seen in the head on the beer and as fine streams of gas rising through the beer. The visible streams will be less evident in cask conditioned beers but the carbonation can still be detected in the mouth. The sharp prickling sensation on the tongue is the small bubbles of CO2 bursting to form carbonic acid. The use of sparklers to create a tight creamy head also forces the CO2 out of the beer leaving it in poor condition.

Formation

CO2 is formed as a by-product of the fermentation process. Some bottled beers and all keg beers have extra CO2 added to increase the level of carbonation.

Examples

Coopers Sparkling Ale has a high level of natural carbonation.

Recognition

Diacetyl has a butterscotch aroma and taste. It can be tasted at quite low levels (0.05 ppm) and recognised at 0.15 ppm.

Formation

High levels are also caused by under-pitching yeast, long wort cooling, poor cleaning of equipment, racking too early, excessive acid rest and a high level of adjuncts in the wort.

Examples

 High levels are a common problem with poorly brewed homebrew. Sam Smiths Nut Brown Ale has a moderate level of diacetyl.

Recognition

DMS has the distinctive smell and taste of cooked vegetables and corn. It can be tasted down to extremely low levels (30ppb). 

Formation

Mainly caused by slow cooling of the wort, which produces the precursors to DMS. The wort bacteria Obesumbacterium of Hafnia also produce DMS. Some coliform bacteria strains can also produce a strong cooked vegetable taste.

Examples

 DMS is never found in well-brewed beer.

Recognition

It is possible to recognise a whole range of fruit tastes in beer, including strawberry, grapefruit, banana, raspberry, pear, peach and apple.

Formation

The fruity taste can come from the hops, as a by-product of the fermentation process or from the yeast strain. The intensity and character of fruit increases with higher fermentation temperatures

Examples

Depending on the beer style, fruity tastes can be intentional or a fault in the brewing process. Old Nick barley wine and Landlord are two beers with distinctive fruit tastes.

Recognition

The aroma of fresh cut grass.

Formation

The grassy aroma and taste is derived from the use of grain that has been stored in warm, humid conditions or milled too early and left in poor storage conditions for many hours before use.

Examples

This is not a normal taste in beer.

Recognition

The taste of stale nuts and damp grains.

Formation

The grainy taste is derived form the starches and tannins in corn and other adjuncts. The husky taste comes from the tannins in the husks of the grains. Over sparging can increase the level of tannins.

Examples

Some beers are brewed to exhibit a nutty taste. Or brewed with oats and other grains to give a distinctive taste. These will have a pleasant aromas and taste from beers brewed with poor quality malts.

Recognition

A light-struck beer is easily recognised by its skunky aroma.

Formation

Light with a wavelength between 400 and 500 nm can cause a photochemical reaction within the hop resins in the beer.

Examples

Leave a green glass bottle containing beer out in the sun for a few hours and it will exhibit the characteristic light-struck aroma and taste.

Recognition

The metallic taste is most prominent on the tip of the tongue and roof of the mouth. It has a slightly tingling, polished taste.

Formation

The metallic tastes can come from a range of sources, including the iron content of the brewing equipment, organic compounds formed by hydrolysis of cereal lipids in the grains, oxidation of free fatty acids and water with a high iron content.

Examples

This is not a normal taste in beer.

Recognition

The smell of damp earth, mouldy bread and old cabbage.

Formation

Fungal contamination during fermentation and storage are the main causes of the mouldy taste and aroma.

Examples

This is not a normal taste in beer.

Recognition

Oxidation is recognisable from its damp cardboard aroma and taste.

Formation

Oxidation can occur at any point throughout the brewing process. The process involves the combination or the reaction of compounds in the beer with oxygen to form fusel alcohols, trans-2-nonenal and acetaldehyde.

Examples

Oxidation is a sign of poorly brewed beer, poor quality or old ingredients and old beer. It is not a desirable taste.

Recognition

Phenols have a distinct hospital or medicinal flavour and aroma. They may also remind you of cloves or have a smoke taste and smell.

Formation

The phenolic taste can come from the yeast strain, chlorophenols in the water, residuals from the chlorine sanitizer and incorrect sparging with water at too high a temperature or pH.

Examples

Belgium wheat beers tend to have a high amount of phenol 4-vinyl guaiacol to give the characteristic taste of cloves.

Recognition

Salty is one of the four basic tastes. It has a harsh taste that is unpleasant even at low levels.

Formation

The salty taste comes from the mineral salts in the brewing water, including sodium chloride and magnesium sulphate.

Examples

The brewing water for IPAs is usually 'Burtonised' by the addition of gypsum salts. Bass ale has a distinct aroma from its high mineral content.

Recognition

This can be one of several aromas and tastes. Acetone, lacquer, nail polish remover and thinners are all examples. It is a pungent, acrid aroma that is followed by a harsh, burning sensation on the tongue and at the back of the throat.

Formation

The main cause is ethyl acetate from wild yeast and some strains of brewing yeasts. It can also leach from plastic equipment and be caused by too high a fermentation temperature.

Examples

Solvent-like aromas and tastes are a sign of a poorly brewed beer.

Recognition

Sour is one of the four basic tastes. It gives tartness in the mouth and leaves a dry sensation.

Formation

Excessive citric acid or ascorbic acid can also cause sourness. Excessive acid rest, mashing for too long, fermenting at too high a temperature and storage in warm conditions can also cause sourness in beer.

Examples

Lambic beers have a distinctive sourness caused by the wild yeast used for fermentation.

Recognition

Rotten eggs have a distinctive sulphury aroma and taste.

Formation

The amino acids methionine and cysteine in the malt, some yeast strains and bacteria such as zymononas, pectinatus and megasphaera can form hydrogen sulphide. The sulphury taste is also formed by the degradation of yeast or autolysis.

Examples

Sulphur is an undesirable taste in beer and a sign of poor brewing, poor storage or contamination.

Recognition

Sweetness is on of the four basic tastes. At excessive levels it can be cloying and unpleasant.

Formation

The sweetness of a beer depends on the level of residual sugars. High levels can be caused by the use of low attenuating yeast, a lack of yeast nutrients in the wort or poor fermentation due to a lack of oxygen. Sweetness can be deliberately increased by the addition of non-fermentable sugars.

Examples

Traditional English brown and mild ales tend to taste sweet, although in some cases this may not be due to an excess of sugar but a lack of hop bitterness to balance the sweetness of the malt.