Accelerated convective drying of sunflower seeds by high-power ultrasound: Experimental assessment and optimization approach

Abstract

The objective of the present issue was to inquire the effect of ultrasound assisted convective drying on a thin layer of sunflower seeds. The process was carried out utilizing a hybrid chamber dryer, outfitted with an ultrasound generator with indirect transmission toward the material surface. Drying behavior was analyzed by drying time, effective moisture diffusivity (Deff), energy consumption (EC), water activity (aw), and total color change (ΔE). Independent variables of air temperature and ultrasound power determined the efficiency of sonication during drying. So that, ultrasound contributed to a noticeable increase in Deff up to 44.84%. Thereafter, a reasonable decrease was found in drying time, energy consumption, and total color change up to 40.85%, 32.95%, and 44.56%, respectively when collocating the variables of 35°C, 3.5m/s, and 2.4W/g. The optimum drying condition in the pure convective drying domain was improved from 50.74°C and 2m/s to the condition of 40.64°C, 2m/s, and 3.932W/g after sonication. In this point, significant reductions of 19.89% and 19.32% were observed in drying time and energy consumption. Optimization results confirmed that ultrasound intervention could provide an intensified and energy-efficient drying process, which generates sustainable and qualified dried seeds.