Extraction optimization by response surface methodology and characterization of Fucoidanfrom brown seaweed Sargassum polycystum

Fucoidanwere recovered from Sargassum polycystum by single-step extraction with ultrasonic wave pretreatment (amplitude 80%, 15 minute). Extraction wereoptimized using central composite design ofrespon surface method. Ultrasonic wave pretreatment conditions were 80%amplitude, for 15 minute. Alga solution in 0.03 MHCl ratio 1:20 (b/v) at70-90°C for 3-5 hour were evaluated duringthis process to establish a condition to maximize the extraction. The yield (%), total carbohydrate (mg/g), fucose (mg/g) and sulfate contents (mg/g) were also determined for eachexperimental condition. The result showed thatall extraction factors had significant effects (p<0.05) onfucoidan yield, fucose, total carbohydrate and sulfate contents. The optimum conditions were 81°C for 4.04 hours. The validated experimental crude fucoidanyield were7.15±5.58%, 131.15±1.92 mg/g fucose, 396.8±65.58 mg/gtotal carbohydrate and 94.67±1.37 mg/g sulfate contents. Characterization of crude fucoidan by FTIR and HPLC showed that crude fucoidan (Sargassum polycystum) is composed by fucose, xylose, galactose, rhamnose, glucose, mannose and sulfate.