Seaweed samples were air-dried in a forced circulating air-drying oven (GallendkampPlus II, Weiss Technik, UK) after ultrasound pre-treatment. The forced circulating air-drying oven was set at 50C.
The air velocity inside of the oven was maintained at 0.3 m s1 and measured using an anemometer
(Testo 400, Total Temperature Instrumentation, Inc. USA).
Seaweed samples were kept in trays and were transferredto the forced circulating air-drying. Samples were weighed every 10 min for the first 1 h of drying, every 20 min for the next 2 h, and every 30min for the next 2 h and finally until constant weight was observed.