Changes in Barley Kernel Hardness and Malting Quality Caused by Microwave Irradiation

Abstract

Malting quality of feed and malting barley treated by microwave irradiation for 0, 4, 5, 8, 10, 15, 20, and 25 sec was evaluated. Microwave irradiation periods longer than 10 sec increased kernel temperature higher than the physiological limit and significantly affected germination. With 4 sec of microwave irradiation, barley kernel hardness decreased and transformed into malt of good quality. The feed barley Adabella without treatment showed double the hardness (49.3 N) and Pastor Ortiz showed almost three times the hardness (59.8 N) of malting barley Esmeralda without treatment (23.7 N). With 8 sec of irradiation, kernel hardness increased. Irradiation of feed and malting barleys for 4 sec increased the extract content in malt. Barley kernel hardness showed a significantly high correlation with malt extract (r = −0.61; P ≤ 0.001). Extract viscosity decreased with microwave irradiation in all cases. Diastatic power and α-amylase were not affected by the treatments selected for this study. Microwave energy is a new alternative that allows modification of the kernel endosperm in a few seconds and increases the industrial quality of feed and malting barley.