The adjuncts used are generally corn, rice, rye, oats, unmalted barley and wheat which are used in the mash to improve flavour, head retention, mouth feel and clarity. There are other adjuncts such as black teacle that can be added however the strictest definition of the word ‘adjuncts’ means anything that is added to the mash.
Adjuncts have been considered inferior due to their use in mass produced beer where they are sometimes used as a cheaper alternative to grain. The German purity laws were introduced in 1516 to ensure that ‘true’ beer contained only three ingredients water, barley and hops. These laws were followed in Germany right up to the twentieth century. However adjuncts are now recognised for the improvements they can bring to beer and are adding an edge to existing beer styles for example Oat Stout.
Here is a list of a few adjuncts and the qualities they add to a beer:
Oat: Is now a popular addition to stout as it adds smoothness and mouthfeel.
Rye: Another adjunct that is used for it’s distinctive flavour it adds a rustic, spicy character to beer and is used in Rye Pale Ale where it is substituted for part of the barley malt.
Rice: Not commonly used by home brewers. Budweiser use rice as they claim it creates the ‘snap’ in their beer. It also helps with colour when making lighter beers.
Wheat: An example of this that springs to mind is torrified wheat which is used in Belgian style ales to add body and head it is especially useful for this in English Ales as well.
Corn: Helps in brewing a beer that has a lighter flavour, body and colour. It is a popular adjunct in America and imparts a corn flavour to the beer which means it is good to use with lagers.
Unmalted Barley: Adds flavour, richness and head retention. However it can contribute to chill haze so it isn’t used as an adjunct in lighter beers, hence it is ideal for Guinness.
This is just a brief guide to adjuncts but one thing which is important is to always use the correct ratio of adjunct to malted barley.