Chemical and gelling profile of ice-ice infected carrageenan from Kappaphycus striatum (Schmitz) Doty sacol strain (Solieriaceae, Gigartinales, Rhodophyta)

The occurrence of ice-ice disease in farmed Kappaphycus spp. has tremendous implication on the carrageenan industry in the Philippines. To elucidate the effect of this disease on the carrageenan quality, the chemical profile of carrageenan extracted from healthy and diseased Kappaphycus striatum sacol strain, was investigated using C-13 and H-1 NMR, FT-IR and GPC methods of analysis. The native carrageenan extracts were composed predominantly of kappa carrageenan with trace amounts of iota and 6-O-methylated carrageenan. Structural evidence indicates depolymerization of carrageenan from the ice-ice infected portion of the thallus (whitish and soft part) lowered levels of iota and methyl constituents. This finding was correlated to its low number average molecular weight (30 kDa) value. Accordingly, appreciable decreases in carrageenan yield, gel strength and viscosity and increase in syneresis index were noted. On the other hand, archetype quality of kappa-carrageenan was observed from both healthy and uninfected portion of the diseased thalli.