Performance of Husked, Acid Dehusked and Hull-less Barley and Malt in Relation to Alcohol Production

Abstract

Studies carried out on normal husked barley, normal hull-less (naked) barley, acid dehusked barley and acid dehusked hull-less barley, as well as the malts derived from them, showed that when acid dehusked barley samples (obtained from either husked or hull-less barley), were processed using commercial enzyme preparations, they produced more alcohol when compared with the alcohol yield obtained from the barley samples from which the acid dehusked samples were derived. When the husked (Optic) control, acid dehusked and hull-less barley samples were malted, Optic control barley produced malt that gave higher dextrinising units (DU) and diastatic power (DP), whilst acid dehusked Optic and hull-less barley produced malts that gave similar DU results on day 5 of the germination time. When mashed, acid dehusked (Optic) barley malt produced wort that filtered faster than the wort obtained from the malt made from hull-less barley. This observation is very important because it shows that the husk of the barley is not the only factor that determines the filtration performance of the malted barley, since both the malt samples made from husked and acid dehusked barley had similar filtration rates on day 5 of the germination time. The slow filtration rate observed for the wort made from hull-less barley suggests that other factors play some role during the filtration of the mash made from hull-less barley malt. Although hull-less malt appeared to develop lower DU and DP enzyme activities, when compared with the values obtained for the Optic control, hull-less barley malted faster and produced optimum predicted spirit yield (PSY) at day 4 of the germination time. In contrast, the control husked Optic barley malt that had higher DU and DP produced equivalent (optimum) predicted spirit yield one day later at 5 days germination time. This is an advantage for hull-less barley, both in terms of time and energy saving during the malting of barley. Although the acid dehusked Optic barley produced more alcohol than the husked control when commercial enzyme preparation was used to process barley, it was surprising that when the derived malt was assessed, it gave a lower predicted spirit yield than the husked control, even though it produced a higher amount of hot water extract (HWE). The higher extract yield and lower predicted spirit yield obtained from the malt made from acid dehusked malt confirmed that high extract yield is not necessarily associated with high fermentable extract.