The more you discover about beer and brewing the more, it seems, there is to learn. In part one of our alphabetised series, we lift the lid on brewing tastes, flavours and terms used. Explaining what they mean and how they come about.


It’s true to say that many beer drinkers enjoy a dry and bitter tasting beer, but what is it that causes dryness and bitterness and what’s the difference between these two taste characteristics?

Astringency is a dryness of the mouth, particularly the cheeks, upper palate, and tongue. It is primarily caused by tannins in beer that make the surface of the mouth contract and leave a ‘puckering’ mouthfeel.

Tannins are a form of polyphenol, they are what give tea its distinct characteristics and they occur naturally in malted grains. If grains are over-crushed or the mash over-sparged tannins will increase. That’s why breweries attempting to squeeze the last drop of wort from their malt are more likely to end up with a dryer, harsher beer than those who are more generous with their raw materials.

Wood can also release tannins into beer with some brewers deliberately using wooden fermenters or casks to create dryer beer. However, it’s important to remember microbial contamination is more likely in wood than in stainless steel or aluminium cask. So poor quality control or a lack of cleaning can lead to unpleasant flavours caused by Lactic and Acetic acids from resulting infections.

Not to be confused with dryness (astringency), bitterness is a different characteristic of flavour. Bitterness is caused by iso-alpha acids from hops during the wort boil. These stimulate particular taste receptors at the back of the tongue and in the throat and provide that recognisable lingering bitterness experienced after swallowing.

A successful brew achieves the right balance of dryness and bitterness. The right amount of astringency will ensure your beer will have a good mouthfeel with residual sugars providing a smooth body (viscosity) and the correct balance of graininess, dryness and bitterness will deliver a memorable drink.


What is a well-balanced beer? You often hear the term ‘balance’ when describing wine but can a beer be well balanced or is the term a misnomer in brewing? The concept of balance refers to the mix of sensory characteristics that make up a beers flavour profile. It’s fair to say that the taste of a beer will depend on a drinkers personal preferences and sensitivity but, in general terms, a poorly balanced beer will be less well received than a well-balanced one.

A particular beer will have one primary flavour profile. For example:

  • Crisp and Clean (eg. Pale Ale)
  • Hoppy and Bitter (eg. IPA)
  • Malty and Sweet (eg. Lager)
  • Dark and Roasty (eg. Stout)
  • Smokey (eg. Porter)
  • Fruity and Spicy (eg. Saison)
  • Sour and Tarty (eg. Sour)

While a primary flavour gives a beer its character it’s also important to have additional secondary flavours to back up the primary flavour and it’s this subtlety which differentiates one brand from another. Not all secondary flavours will be detectable to everyone however as each of us has limits to our sensitivity and these vary according to our heredity and experience. So you may notice a flavour characteristic that a drinking partner does not or vice versa.

But in general beers with high levels of primary flavour are perceived as being too bland. Brewers should aim for a fine balance of primary and secondary flavours as it’s this that makes a great beer. For example, a bitter IPA may also have a fruitiness, caramel, spiciness secondary flavour achieved by complex grist mixtures, imaginative hop additions and careful maturation.

How a beer feels in the mouth is also important. A good body benefits the overall richness of a brew. It should be low in thin, drinking beers, like lager and pale ales, but high in complex beers like porters, stouts and milds. It will encourage a beer to be savoured with relish rather than drunk with abandon that’s why it is often excluded from mass-produced brands. However, today’s’ craft brewers have the opportunity to concentrate on the all-round character of their beer and not leave a drinker disappointed wondering why the flavour of their pint vanished so quickly.

Chill Haze

Ever pulled a beer from the fridge to find it less bright than when it went in? If so you are likely to have experienced the effect of chill haze – the precipitation of the beer’s proteins and tannins induced by low temperatures.

Naturally, this affects the overall impression of the beer and in a bar may lead to a serious discussion over the beer’s quality or even rejection. The Chill Haze effect is reversed when the beer warms up – although this may only add to any disagreement!

Brewers, bar staff and beer drinkers seeking clarity (get it?) can trace the origins of Chill Haze to the proteins and tannins from the malts used in the brew. Malts typically release about a gram of protein into a litre of beer much of which remains to produce its mouthfeel and the foam forming the head. Some, however, can interact with itself to form large complex molecular structures.

Much of this happens during maturation but high protein malts or short maturation times can also lead to residual levels of proteins which can make a beer more susceptible to haze. Low temperatures then induce this although this will have no discernible effect on flavour. Temporary chill haze can become permanent with time so bottles at the back of the fridge may differ from one regularly replenished at the front.

Brewers can reduce the chance of chill haze by their choice of malts and processing times but also by adding in an adsorbent such as PVPP (polyvinylpolypyrrolidone) to remove polyphenol tannins or an enzyme to digest the protein. These additions are often standard in large scale production but may be undesirable in small scale craft beers. Polyphenols and proteins do contribute to flavour and physical features of beers and their extensive removal may change its character. Perhaps a little temporary haze is a small price to pay for a more natural beer.

Dimethyl sulphide

What does warm lager smell of? A question an ale drinker may rarely consider important or worth investigating. Dimethyl sulphide or DMS is, however, a pungent flavour in many beers giving a range of unusual vegetable smells to lighter beers, including at times, bitters and pale ales
To experience the full character of DMS agitate a warmish half pint of lager in a pint glass and breathe deeply. A variety of vegetables are likely to dominate the aroma. Identification of these may be easier for some people than others but onions, sweet corn, cooked cabbage and occasionally parsnip or celery are typical associations.

A certain low level of these is natural in lagers and should blend with other flavours, particularly hop character to provide a rich and pungent character to the beer. In ales, even lower levels would acceptable and should never dominate the typical malt and hop characteristics of standard bitters and pale ales and dark ales typically have a strong roast or caramel flavours that easily overpower any DMS which may develop.

DMS comes from the malt but occurs at much lower levels in ale malt due to its higher roasting temperature (lager malt is dried at lower temperatures). Excessive levels of DMS in real ale could occur if lager malt is used by mistake but is more likely be from a bacterial infection. Such bacteria are typically killed by alcohol but can produce enough DMS to carry through to your pint before they die.


Written by Dr Keith Thomas
Brewlab Director

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