Drying kinetics
Ultrasound pre-treatment had a positive impacton the seaweed drying rate during hot air convective drying.
The drying process is characterized by a progressive decrease in moisture content with time.
For comparison reasons, the dimensionless moisture content was calculated and its change during drying of A. nodosum is presented in Fig. 4.
The moisture content decreased gradually for un-pretreated samples, while a decrease in moisture content was observed at the highest ultrasonic intensity of 75.78 W cm2 studied.
Ultrasound pre-treatments reduced the time required to dry A. nodosum.Drying time for different pre-treatment swere 457minat 75.78 W cm2, 467min at 35.61 W cm2, 470 min at 7.00 W cm2 and 523min for untreated samples.
Thus, with increase in ultrasound power there was a significant reduction (P < 0.05) in drying time for A. nodosum.
At the highest power investigated a reduction of 12.62% in drying time was observed.
Fernandes et al. [16] used ultrasound treatment to reduce the total drying time from 814min to 734min.
This reduction in drying time can reduce energy consumption as previously reported