ULTRASONIC-ASSISTED EXTRACTION OF ANTIOXIDANT PHENOLIC COUMPOUNDS FROM EUCHEUMA COTTONII

Abstract

The influences of ultrasonic-assisted extraction (UAE) conditions on phenolic compounds of Eucheuma cottonii seaweeed were investigated. The effects of temperature, time and liquid-solid ratio were evaluated based on the total phenolic content (TPC). The result showed a significant variability of effect of temperature, time, and liquid-solid ratio on TPC. Application of ultrasound reduced the optimum temperature, time and liquid-solid ratio of the extraction when compared to the conventional extraction. The highest phenolic content (4.44 mg gallic acid equivalent/g dry weight) was obtained at 3:1(v/w) of liquid-solid ratio, 55^oC of temperature and 35 min of extraction time. At this condition, the extract showed ability to scavenging 91% of 1,1-diphenyl 2 picrylhydrazyl (DPPH radical) and 10.9% of H₂O₂. High ability of the extract to scavenge DPPH radical but low in scavenging H₂O₂ indicated that the extract dominated by primary antioxidant compounds which work by donating hydrogen atoms to bind free radical.