Ultrasound-assisted hydration of wheat grains at different temperatures and power applied: Effect on acoustic field, water absorption and germination

Wheat has been increasingly employed as malt in the food industry. As the malting process demands long processing time, ultrasound can be a clean intensifying alternative. This work studied the ultrasound-assisted hydration of wheat grains at different nominal input power (0 - 1500 W) and temperatures (15 - 25 degrees C). The actual acoustic field within the reactor was characterized. The effects of the studied variables on hydration kinetics were assessed separately by the Weibull and Peleg Models. Thermodynamic parameters were evaluated. Grains germination was also addressed under the studied conditions. Increasing temperature as well as higher acoustic density caused an improvement in the hydration kinetics, reaching 72 % when both variables were combined. Hydration was an endothermic and non-spontaneous process. In the range of actual acoustic density (0.061-0.102 W mL(-1)) and hydration temperature, the maximum germination was kept at similar to 5 days with 86 % germinated grains.