Exploring the Growth Dynamics, Carrageenan Yield, and Bioactive Properties of Eucheuma spinosum Cultivated with Different Methods

      Eucheuma spinosum, a type of macroalga, is cultivated in Indonesia for applications in food, medicine, and cosmetics. This alga produces iota carrageenan, which is softer than kappa carrageenan. The objective of this study was to analyze the growth, carrageenan yield, and bioactive compounds of E. spinosum grown using different cultivation methods. Conducted in Gerupuk Bay, Central Lombok, West Nusa Tenggara, Indonesia, from June to September 2024, this research employed an experimental method with a completely randomized design. The treatments compared two cultivation methods: floating rafts and bottom-off. Observed parameters included growth, carrageenan yield, thallus slices, proximate composition, chlorophyll-a, phycoerythrin, and carotenoids. The results showed that the absolute weight of E. spinosum was 74.7g on floating rafts and 150.775g on bottom-off. The specific growth rates were 2.01 and 3.99%/day, respectively. Carrageenan yields were 24% for the bottom-off method and 11% for floating rafts. Carotenoid contents were 6.69 mol/L on floating rafts and 4.23 mol/L on bottom-off. Phycoerythrin levels measured 2.69µg/ L on floating rafts and 0.91µg/ L on bottom-off. Chlorophyll-a content was 5.42mg/ L on floating rafts and 1.38mg/ L on bottom-off. Proximate analysis revealed the following for floating rafts: water content 28.2098%, ash 32.0270%, crude fat 0.0199%, crude fiber 4.5991%, and protein 7.9170%. For the bottom-off method: water content was 31.6676%, ash was 30.7466%, crude fat was 1.7061%, crude fiber was 6.0548%, and protein was 4.3919%. The study concluded that E. spinosumcultivated using the bottom-off and floating raft methods exhibited differences in growth, carrageenan yield, pigment content, and proximate composition.