Iota-carrageenan from a newly farmed, rare variety of eucheumoid seaweed-endong

A seaweed with the local name endong is a rare eucheumoid variety that has recently been farmed in Tawi-Tawi, southern Philippines. Local farmers describe it as eel-like because of its long, slender and smooth thalli. Being somewhat similar in appearance to the dominantly farmed seaweed tambalang (Kappaphycus alvarezii var. tambalangii), farmers mix their harvests of endong with those of tambalang. We analyzed the hydrocolloid extract from endong using spectroscopic and chemical techniques. The extract's infrared and nuclear magnetic resonance (H-1 and C-13) spectra, and sulfate and 3,6-anhydrogalactose contents revealed carrageenan of the iota-type, similar to extracts from another farmed species, Eucheuma denticulatum. This result implies that endong carrageenan exhibits physico-chemical properties different from those of kappa-carrageenan of tambalang. The findings of this study are of significance to the seaweed industry, as carrageenan quality problems could potentially arise from a mixed harvest. Seaweed farmers are advised to separate their harvests of endong and tambalang.