Coloured Malt Production

The manufacture of coloured malts requires intensive energy usage, capital investment, supervision, technology and quality control. Most importantly it requires highly skilled and experienced operators. The very high capital investment is needed to purchase and maintain the specialised equipment needed in the modern roast house.

All coloured malts are now produced in a roasting cylinder or drum. The size of these machines vary from those capable of handling a batch of 500 kilograms to the modern high capacity machines capable of handling a batch of 3.5 tonnes. These machines, which are modified coffee roasters, rotate at approximately 30 r.p.m. They are fitted with vanes which impart a dual mixing system on the grain. This ensures an even roast and minimises corn damage.

The drum is heated by oil or gas burners which provide uniform heat along the drum. These burners are accurately controlled to enable the operator to maintain the correct temperature profile throughout the roast. Above right is a typical roasting control. It is capable of providing either direct heat through the grain or indirect heat around the cylinder. With direct heating, hot dry air passes through the drum; for indirect heating the grain is heated at a constant moisture level giving a “stewing” effect.