Malt is one of the 4 primary ingredients in beer, and the number of different malt varieties can be truly mind-boggling. It’s easy for new brewers to be overwhelmed, but this introductory guide to malt is here to help!
Malt is most commonly produced from barley. Two major types of barley are common, called two-row and six-row barley. They are named after the number of rows of kernels around the central shaft. Two-row barley is generally preferred for brewing as it contains less protein and has more uniformly sized kernels. Six-row barley is still sometimes used in American lager styles, but it is combined with adjuncts like corn to dilute the protein levels. Malt can also be made from wheat and is a primary ingredient in wheat beers.
Remember from the article on how beer is made that yeast eat sugar to make alcohol? Well that sugar comes from cereal grains! Beer is primarily made from malt, but sometimes other grains such as corn or rice are added to change the colour or flavour of the finished beer. These unmalted grains are called adjuncts, and are usually only used in small quantities.
To be able to use the sugars in grains for brewing the grains need to be malted. The grains are filled with a giant sugar molecule called starch. Malting produces enzymes that break the starch down into small sugars that the growing plant can use for food. To produce those enzymes the seeds need to be brought to life. Malting begins by soaking the grains in water, which causes them to start sprouting. As the grain comes to life it begins producing the enzymes that unlock the sugars. These enzymes are used later by the brewer in a process called mashing to convert the sugars from the grains. Once the grains have germinated enough and the internal structure of the grain is fully modified, they are dried. Drying stops the germination process and locks in the desired qualities of the malt.
After drying, malts are kilned. The temperature and length of the kilning process determines the characteristics of the final malt. Malts kilned at a low temperature are called base malts, and are used for the majority of the grain bill of a beer. Specialty malts are made by kilning at different temperatures. Higher kilning temperatures produce lightly roasted malt, which is used in smaller quantities to add flavour complexity and darker colour to a beer. Highly kilned, heavily roasted dark malts give beer a burnt, bitter flavour and dark colour. They are used in small quantities to make dark beers such as stouts and porters.
Crystal malts are made by wetting and roasting the malt before it is kilned. This process converts the starch into sugar inside the grain, which means the grains don’t need to be mashed to extract the sugar. Like other malt, crystal malt can be kilned to different temperatures to create different flavours and colours. Lightly kilned crystal malt gives toffee or caramel flavours to a beer when used in smaller quantities which is pleasant in pale ales. Dark roasted crystal malt gives a flavour like sultanas or port which adds interesting depth to darker beer styles.
So here is where the complexity comes from. A single grain, barley, can be converted into base malt, specialty malt, roasted malt and crystal malt. And within each of those malt varieties there are different degrees of kilning that change the flavour and colour of the finished beer. So many possibilities from one little grain!