Lesson 4 - Adjunct Composition and Application

Historically, adjuncts were used as an additional source of extract to replace or supplement malt. Today, adjuncts are used to reduce raw material costs, extend brewhouse capacity without the need for significant capital expenditure, and to provide beers with specific attributes such as particular flavours and improved foam stability.

Reducing costs

As we discovered in the Malting Process lesson, malt production is complex and energy intensive. The manufacturing process employed for many adjuncts is simpler and uses less water and energy. As a result, adjuncts can be purchased more cheaply. In addition, in certain countries, malting barley may not be as widely available as other cereals (maize, sorghum, and rice, for example) increasing this disparity in price. Having said this, some adjuncts are expensive to produce, so these are used to improve beer quality or increase brewhouse capacity, rather than to reduce production costs.

Extending brewhouse capacity

Later in this course, we will learn that the limit on the volume of beer a brewhouse can produce is typically determined by the maximum amount of grist the mashing and wort separation vessels can process effectively. Adding adjuncts that provide sugar after wort separation enables us to increase (or extend) the output of the brewhouse without the need to install much in the way of additional equipment.

Adding sugar sources after wort separation can also facilitate an increased number of brews per day. If we reduce the amount of malt used in each brew, we will have less malt to mill and mash in, and fewer spent grains to discharge. This reduces the time taken for each process. Furthermore, reducing the mash bed thickness and wort gravity enables wort to be run off from the wort separation vessel at a faster rate. In combination, each of these individual time savings add up to provide a significant reduction in wort production system turnaround times.  

Affecting wort fermentability

Adjuncts added after wort separation provide sugar direct to the wort. It is possible to specify the proportions of each type of sugar in the adjunct. This means we can increase the fermentability of the wort by increasing the proportion of fermentable sugars. Furthermore, when processed in the correct way, adjuncts added to the mashing vessel can provide starch, which is more readily converted in the mash than that of malted barley. This increases the concentration of fermentable sugars in the wort and hence the fermentability. This can be achieved using the adjuncts grits, flour, or purified starch powder. Increasing the wort’s fermentability will of course change the characteristics of the finished beer. This leads us nicely on to our next topic of discussion.

Influencing beer flavour

Beers brewed using just malted barley tend to have fuller palates and aftertastes than other beers. With stronger beers (above 8% abv) in particular, this can cause them to be satiating and in turn less drinkable. It is widely believed that many forms of adjunct result in a beer with a lighter, cleaner flavour. For example, the Belgian strong golden ale and tripel styles are brewed using adjuncts that provide additional fermentable sugars. These additional sugars help to make them less cloying than all-malt barley wines of an equivalent alcoholic strength. Many well-known international lager brands use rice and maize as sources of starch, making the resulting beers lighter in palate than lagers brewed in accordance with the Reinheitsgebot.

We must avoid viewing adjuncts as just ‘diluters of malt flavour’. Each type of adjunct will have a particular impact on the attributes of the finished beer.

Wheat contains high molecular weight proteins that become soluble during mashing. These proteins can increase palate fullness. They also increase levels of haze in the finished beer, which is essential for certain beer styles. Wheat is of course the key ingredient in witbier/biere blanche and weissebier (wheat beer) styles. Oats are also used by some craft brewers, who believe that they provide a silky palate and increase levels of haze.

Beer flavour is very complex and there are many unknowns. The impact of any raw material is influenced by the other raw materials in the recipe, the equipment used, and the process parameters. Some flavour compounds can promote the contribution of others, while some can mask or remove them. There are very few scientific ‘facts’ about the flavour contributions of raw materials, so brewers must rely on anecdotal evidence. As brewers, we need to be careful about who and what we choose to believe. When brewing, the impact of adding a raw material to affect a change is never as simple as adding another spoonful of sugar to a coffee to sweeten it!

This article describes the effect of different varieties of wheat and of barley malt modification on beers brewed on a laboratory scale.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2004.tb00203.x

Improving foam stability

We will cover beer foam in more detail in Module 2 of the Diploma in Brewing. Foam is formed as gas (carbon dioxide and nitrogen) leaves the beer in the form of bubbles. The bubbles form the foam on the beer and are stabilised by foam positive material. Without this material, the beer would have no head, much like champagne. The biggest contribution to the stabilisation of the foam is made by the degradation products of high molecular weight proteins. As we discovered earlier, wheat is a good source of these, and is thus sometimes used to improve beer foam stability. As other forms of adjunct do not add significant amounts of protein or polypeptide, beers brewed with high proportions of these can suffer from poor foam stability.

The article below discusses the use of wheat in brewing.

https://onlinelibrary.wiley.com/doi/full/10.1002/jib.107

Improving colloidal stability

Colloidal stability is how unlikely a filtered beer is to form a haze over time. A beer with high colloidal stability will not go hazy before the end of its shelf life. While reducing the concentration of proteins and polypeptides in the beer is bad news for foam stability, it is good news for beer clarity. Beer haze is composed of proteins and polyphenols. Both of these are provided by the malt, so by reducing the proportion of malt used to make the beer, we can reduce the potential for haze formation in the package.

So, adjuncts are more than just a cheap source of extract (and, yes, this lesson is at risk of becoming an advert for using adjuncts!). To add some balance, in the next section we will discuss some of the disadvantages of using adjuncts.