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Abstract
This study aimed to optimize ultrasound-assisted extraction (UAE) conditions of the red seaweed Gracilaria salicornia (G. salicornia) for total phenolic content (TPC) with antioxidant power using response surface methodology (RSM) based on a Box-Behnken design. The effects of various extraction conditions on TPC and antioxidant activities of G. salicornia were investigated including extraction temperature, extraction time and material to solvent ratio with water selected as the extraction solvent. The results indicated that extraction time and material to solvent ratio signifi cantly affected TPC of G. salicornia (p < 0.05). Of these, extraction time had a positive effect on TPC, while material to solvent ratio had a negative effect. Additionally, the optimum ultrasoundassisted extraction conditions were found to be extraction temperature of 60 °C, extraction time of 40 min and material to solvent of 3/100 (g/ml). Under these conditions, the experimental yield of total phenolic compounds and ferric reducing antioxidant power were 93.95 ± 3.05 (mg GAE/100g) and 54.76 ± 0.89 (mg TE/100g), respectively.
Keywords: Gracilaria salicornia, polyphenol, antioxidant capacity, ultrasound-assisted extraction