Karakteristik Karagenan dari Rumput Laut dan Hasil Samping Garam (kappaphycus alvarezii) di Pulau Sebatik Menggunakan Pelarut Natrium Hidroksida (NaOH)
Kappaphycus alvarezii seaweed is a primary source of carrageenan, possessing significant economic significance and extensively cultivated in coastal regions, including Sebatik Island. In the manufacture of seaweed salt, waste is generated that has not been effectively utilized. This study aimed to assess the properties of carrageenan derived from the by-product of the K. alvarezii seaweed salt production process utilizing sodium hydroxide (NaOH) as a solvent. The parameters analyzed included yield, moisture content, sulfate content, ash content, and viscosity. Extraction was carried out using the hot alkali method with 0.5% NaOH at 90-95°C for 5 hours, followed by precipitation with KCl, drying, and grinding. The results showed that carrageenan from salt residues had a yield of 21.64 ± 5.81%, moisture content of 6.66 ± 1.52%, sulfate content of 2.72 ± 0.39%, ash content of 32.6 ± 0.57%, and viscosity of 12.6 ± 0.9 cPs. In comparison, carrageenan from whole seaweed showed a yield of 32.8 ± 2.42%, moisture content of 9.66 ± 2.51%, sulfate content of 1.58 ± 0.14%, ash content of 44.33 ± 3.78%, and viscosity of 9.6 ± 0.9 cPs. Although derived from waste, carrageenan from salt residues exhibited competitive physicochemical properties, particularly in terms of water content and viscosity. Thus, seaweed salt by-products have potential as an alternative raw material for carrageenan production, especially for non-food industrial applications.