Research reports on extracts, proteins, total nitrogen and free amino nitrogen content of sorghum malt and worts obtained from mashes indicate that sorghum is potentially an alternative substrate for conventional beer brewing in the tropics. Remarkable variations in biochemical characteristics among different sorghum cultivars affect their optimal malting conditions. Factors such as temperature and time of steeping and germinating of grains with their intrinsic enzymic activities, and kilning temperature determine the quality of malt. Further works on mashing, viscosity and fermentability of worts as well as the character of the resulting beers, such as alcoholic content, colour, taste and specific gravity tend to confirm the status of sorghum as a credible substitute for barley in beer brewing. This review reports on progress made in the use of sorghum for brewing beer.Key Words: Sorghum, steeping, diastatic power, malting, mashing, wort, extract. Storing sorghum grains for 2 to 3 years at 12 to 23°C gives higher level of amylases (between 57 and 73%) while newly harvested grains contain about 25%.Lowering storage temperature to 7°C reduces level of soluble amylases in the grains to about 31% after 3 years.But, storing malts for any period of time seems not to affect soluble amylase content73-76. Nevertheless, malting yields higher proportions of hydrolytic enzymes such as a-glucosidase, a-and B-amylases which may be either completely soluble or largely insoluble22-51-73-119. For example, insoluble amylases and a-glucosidase have been detected in malts from sweet sorghum and related variety. The insolubility of these enzymes is apparently due to their strong adhesion to insoluble malt solids73-119. Malting causes a decrease in density of caryopsis in sorghum grain10, lowers the amount of lysine from 0.25% in unmalted sorghum to 0.18% in sorghum malt84 and also reduces milling energy114. Sorghum endosperm contains both vitreous and mealy regions with the percentage of vitreous endosperm highly correlating with grain hardness42. The vitreous part of endosperm seems to influence grain milling energy and also malt milling energy since it is largely unmodified during malting5. Thus, there is a positive correlation between grain milling energy and malt milling energy115. The loss in milling energy due to starch granule modification during malting may be responsible for the highly significant correlation between diastatic power and malt milling energy. However, grain milling energy shows no significant correlation with percentage extract in P-Amylase is more labile than a-amylase and is influenced by germination time and temperature. A rapid increase in P-Amylase activity occurs within the first 2 days of germination and subsequently declines in rate of increase up to 6.5 days. There are wide variations regarding P-amylase activity of sorghum malt in some reports and this may be due to assumptions that Pamylase activity is the difference between total amylase and a-amylase activities. An assumption which ignores a...
