Physicochemical changes in barley starch during malting

Abstract

The objective of this work was to study the physicochemical modifications of starch during the malting of barley. The results showed that malting modifies the physicochemical properties of the starch over time by the action of barley enzymes. The gelatinisation temperature of starch increased as a function of the malting time owing to the selective enzymatic attack. The viscosity of starch decreased through malting. During germination, scanning electron microscopy showed that the enzymes degrade some starch granules which exhibited micro-holes on the surface. X-ray diffraction showed an apparent increase in the crystallinity during the first three days of germination, reflecting the consumption of amorphous regions. Such changes have not been previously reported. Infrared spectroscopy (1200–1500 cm−1) showed the unfolding of carbohydrates as a result of enzymatic action. Such changes in the physicochemical properties of starch indicate that the amorphous area is consumed in the early stages of malting. © 2018 The Institute of Brewing & Distilling.