Full Length Research Paper

Influence of ultrasonic stimulation on the germination of barley seed and its alpha-amylase activity

Maryam Yaldagard^1*, Seyed Ali Mortazavi² and Farideh Tabatabaie²

¹Department of Chemical Engineering, Affiliated to Engineering faculty, Ferdowsi University of Mashhad, Iran.

²Department of Food Science and Technology, Ferdowsi University of Mashhad, Iran.

*Corresponding author. E-mail: m_yaldagard@yahoo.com. Tel: +985118795618. Fax: +985118787430.

Abbreviations: OD_t = optical density of test sample at 540 nm; OD_s = optical density of the maltose standard; EV = extraction volume (mL); DF = dilution factor; t = incubation time (min); V = used volume of diluted enzyme extract (mL); m = weight of malt flour (g); Mw = molecular weight of maltose.

Accepted 18 October, 2007

In this study, the influence of ultrasonic stimulation was investigated on the germination of barley and alpha-amylase activity grains in the dry state before steeping. All experiments have been performed using an ultrasonic horn operating at a fixed frequency of 20 KHz in 3 different ultrasonic power (20, 60 and 100% setting from total electrical power of device (460W) and time (5, 10 and 15 min) at constant temperature (30^oC). For determining the effects of these parameters, the enzymatic activity was assayed by measuring the reducing sugars released as a result of the alpha-amylase action on soluble starch using 3,5-dinitrosalicylate regent (DNS). The results of these assays were analyzed by Qualitek4 software using Taguchi statistical method to evaluate the factor’s effects on the amount of enzyme activity. The results of assays showed that the activity of this enzyme was increased as a result of the increasing germination rate in the sonicated seeds. Also the findings indicated that both ultrasonic power and treatment time with a contribution percentage as high as 48.456% and 45.273% respectively, had the dominant effects on overall performance.

Key words: ultrasonic stimulation, alpha-amylase activity, germinated barley, Taguchi statistical method.