The level ofbeta-amylase in germinating barley grain and the kilned malt has been examined by assaying for activity, quantitative ELISA and immunoblotting using antibodies specific tobeta-amylase. During germination there is a substantial increase in combinedbeta-amylase activity; the sum ofbeta-amylase soluble in aqueous salt solutions and that extracted in the presence of β-mercaptoethanol (ME). Although previous studies have attributed this increase to activation ofbeta-amylase, here we report that the increase in activity is matched by an increase in the level of combinedbeta-amylase protein as measured by ELISA. Most, if not all, of this additional activebeta-amylase protein is made available by the release ofbeta-amylase from a newly described latent fraction between day 1 and 4 of germination. The latent fraction is extractable with a solution of 1% sodium dodecyl sulphate and 1% ME. Assessment of barley grain and malt from commercial maltsters has confirmed that similar increases in combinedbeta-amylase activity occur in commercial malt houses. Kilning results in up to a 46% reduction inbeta-amylase activity which is associated with a similar reduction in the level ofbeta-amylase protein measured by ELISA.