Practical users of rice, refined corn starch, wheat starch and torrefied cereals are discussed. Brewer's rice, a by-product of rice milling, accounts for < 25% of brewing adjuncts in U.S.A., but finds favour in having lower protein and oil contents and in ease of handling. However, it has a high gelatinization temperature and not all varieties are acceptable. It may be mashed at 97 to 107 degrees F for a protein rest and 5 to 10% of malt is added to the cooker to liquefy the mash sufficient for pumping. Boiling is necessary for gelatinization. After proper conversion, rice adjunct usage does not create runoff problems: the extract is slightly lower in soluble protein and quantitatively exceeds that given by corn grits. Quality of brewer's rice can be judged by cleanliness, gelatinization temperature, mash viscosity, mash aroma and moisture, oil, ash and protein contents. Rice must also be tested and qualified according to variety and growing area. Refined corn starch is dearer than corn grits or brewer's rice and it is more difficult to handle, but is an attractive alternative. Its gelatinization and liquefaction proceed at lower temperatures and brewhouse yields can be 1 to 2% greater than those of rice, fermentations attenuate better and colloidal stability is unaffected. Refined wheat starch is relatively dear in U.S.A., but it is a satisfactory adjunct and has been used in Canada. Chemically it resembles refined corn starch and it can be added directly to the malt mash, although 10% higher yields can be obtained using a mash cooker, in which it may be advantageous to break down beta glucans by treatment at 118 degrees F for 30 min with 10% of the malt before heating to 205 degrees F. With torrefied barley and wheat, cooking is unnecessary, the starch having been gelatinized by torrefication. Torrefied cereals create no handling or dust problems and they can be ground and mashed in with malt, although separate cooking at 160 to 170 degrees F gives better yields. Their use increases the depth of grain bed and tends to create slight runoff difficulties, especially with barley. Mill setting is therefore critical. In comparing adjuncts by analysis, the refined starches give the best and the torrefied cereals the poorest extracts. While the latter have relatively high protein contents, only about 10% of this appears in the wort, the remainder having been denatured by the torrefication process.
Keywords: adjunct brewing rice roasting starch survey