Lesson 2 - Speciality Malt
This lesson deals with speciality malt. Speciality malt is any malted product other than standard pale barley malt. We explore how these malts are made. We discover how using speciality malts or malt extracts, provides different beer flavour, aroma and can also affect colour.
Roasted Barley
One product that is generally considered a speciality malt isn’t a malt at all. That is because it is not malted. Roasted barley, which can provide beer with astringent and burnt flavour does not go through the malting process.
Roasted Barley
To produce roasted barley, a variety with good husk adherence and moisture between 12-16% is used. The barley is directly fired in a roasting drum for around two and a half hours. Over the first two hours, the temperature within the drum rises from 80˚C to 180˚C and subsequently rises to 230˚C. Exact temperatures and timings may vary between malt producers. This causes rapid colour formation that must be monitored frequently (typically 2-3 minutes). The amount of heat applied in the final stages is continually reduced until, when the temperature reaches about 215°C, the burners are turned off. However, the grain is close to combusting and the temperature continues to rise spontaneously for the last 5 minutes or so. Water is used to quench the grain to prevent combustion. When the correct colour is achieved, water is sprayed on the grain to cool it. Some believe the water helps to remove unpleasant burnt flavours, which are volatile, and are removed in the resulting steam. Because the grains are so close to combustion in the later stages of the process, there is a significant risk of fires. Historically many roast houses have caught fire and modern facilities are designed to be safer and to deal with fires that may occur quickly and effectively.
Roasted barley grains typically appear reddish, shiny, black and swollen to almost double their normal size. Consequently, approximately 50% of the kernels are split. Roasted barley colour is typically 1200-1500 EBC, with moistures of less than 3%. It is often used in dark, intensely flavoured beers such as stouts. Because of its intense colour and flavour, very little is required (less than 10% of the grist weight is usually recommended). Because it has not been malted, the extract provided by roasted barley is low, in some cases as low as 65%. It is highly friable and as a result may not be suitable for hammer milling. Huskless roasted barley is available from some suppliers who claim that it contributes less astringent flavour.
2,3,5-Trimethylpyrazine gives a chocolate flavour to roasted barley. A wide range of compounds are formed during roasting, many of which are very flavour active.