Extraction and Characterization of Refined K-carrageenan of Red Algae [Kappaphycus Alvarezii (Doty ex P.C. Silva, 1996)] Originated from Karimun Jawa Islands

The properties of refined κ-carrageenan (RC) extracted from red algae originated from Karimun Jawa Island has never been studied. The objective of this research was determining the effect of KCl on characteristic of refined κ-carrageenan extracted from the red algae [Kappaphycus alvarezii (Doty ex P.C. Silva, 1996)]. The result indicated that higher KCl concentration resulted in the increase of the carrageenan yield, ash and sulphate content, and the decrease of gel strength, moisture and acid-insoluble ash content. The carrageenan viscosity demontrated a fluctuated value due to KCl concentration. This study suggested extraction process by using 2.5% KCl solution. The carrageenan yield was 34.3% and the result demonstrated the carrageenan properties as follow: 8.20 cP viscosity, 94.45 g · cm–2 gel strength, 6.3% moisture content, 59.4% ash content, 1.78% acid-insoluble ash, and 7.75% sulphate content. The absrbance peak at 849 cm–1 detected from infrared spectrscopy indicated D-galactose-4-sulphate which is related with κ-carrageenan.