WATER UPTAKE AND ENZYMIC ACTIVITY DURING STEEPING OF BARLEY

Abstract

During steeping of barley, the increase in moisture content of the grain exhibits two phases, of duration respectively 6–10 hr. and 35–50 hr. In the first phase, the embryo absorbs water preferentially with the endosperm imbibing less quickly. In the second each part absorbs slowly. In the first phase, amylase, ribonuclease and phosphatase activities of the embryo all rise appreciably, paralleling water uptake, but after about the first 6 hr. all fall and only rise again if the steep liquor is changed or if the grain is exposed to the atmosphere. There is no fall in activity if the liquor is drained after 6 hr. Enzyme activities in the endosperm show no appreciable rise until after 4 hr. steeping. In the second place, activity of the whole grain and of the individual parts bears no relation to water uptake. Gibberellic acid stimulates enzymic activity in both embryo and endosperm at very early stages. The importance of these findings in regard to multiple steeping processes is discussed.