Rheological behavior and antioxidant activity of carrageenan extracted from Green seaweed (Eucheuma cottonii) using alkaline solution at low temperature

Seaweed is one of the important biological resources found in coastal and marine regions. One of the main \nproducts derived from seaweed is carrageenan. In this work, the carrageenan was extracted from the seaweed using \nalkaline solution. Two types of bases were used as the extracting solution, namely NaOH and KOH solutions. The \nextraction results showed that the use of KOH solution resulted in a higher carrageenan yield than that extracted using \nNaOH solution. It was also found that the carrageenan yield was increasing with the increase of the basic solution volume \nto mass of the seaweed ratio. The highest carrageenan yield of about 33.4% was obtained using KOH solution at solvent \nvolume to seaweed mass ratio of 45 ml/g. The rheological measurement showed that the rheological behavior fitted best \nto the Power Law model. Meanwhile, the carrageenan extracted using NaOH solution demonstrated higher antioxidant \nactivity. The highest percentage of DPPH radical scavenging activity of the carrageenan extract was 60.7%, while the \nIC50 values were in the ranges of 0.2 – 30 ppm indicating a potent antioxidant activity.