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Effect of Ultrasound and Germination Time on Alpha-Amylase Activity in Wheat Grain
R. CHÁVEZ-PULIDO (1), A. Islas-Rubio (1) (1) CIAD, A.C., , Mexico.

Alpha-amylase as other amylases has multiple applications in the foods and brewing industry. It is a widely distributed enzyme in nature, with a higher activity in some germinated cereals. Nowadays, the food industry applies ultrasound (US) to improve the rate of different processes of germinated grains such as barley, lentils, and chickpea. However, not much is known about its effect on amylase activity and solid loss in germinated wheat grain. The aim of this study was to evaluate the effect of different intensities of US and germination times on the alpha-amylase activity in two wheat grains (Patronato and Onavas varieties). The US was applied to the stepped grains at 3 intensities (27, 81, and 108 W) during 3 min. Samples were germinated at 25 °C and 90% RH up to 7 days, watering the samples 3 times/day. Germinated samples were collected at 0, 1, 3, 5, and 7 days. Then, they were dried at 50 °C for 48 h and ground with a 0.5 mm sieve Cyclotec mill. Alpha-amylase activity was measured by the rapid viscoanalyzer (RVA) and the Ceralpha method. Alpha-amylase activity by Ceralpha was significantly affected by US application, germination time, wheat variety, and their double interactions. Additionally, the enzyme activity by the RVA was significantly affected by the main factors, and the interaction US application*variety was not significant. Solid loss increased and RVA viscosity decreased with germination time. The smaller solid loss (2.4-2.6%) was to 1-day germination. Patronato had a lower (p<0.05) solid loss than Onavas. The US application to Onavas favored the synthesis of alpha-amylase; while did not enhance the activity of this enzyme of Patronato. Overall, the recommendation is 3 days germination for both varieties, to keep solid losses and significantly increase the alpha-amylase activity.