Seasonal variation of the growth, chemical composition and carrageenan extracted from Hypnea musciformis (Wulfen) Lamouroux harvested along the Atlantic coast of Morocco

Abstract

Hypnea musciformis is a common species of the Moroccan Atlantic coast. Both biology and chemical composition of the carrageenan extracted were studied on samples collected monthly during two years on the jetty of Mehdia in the Northwest of the country. The growth of the alga was at its maximum in summer and autumn. Chlorophyll a and R-phycoerythrin (maximum in winter) was the main pigments of the alga. The ash content presented significant fluctuations between 11 to 55% of dry matter. The carrageenan content could reach up to 41% of the dry matter in winter and then decreased in autumn. Its chemical composition did not show marked seasonal variations. Galactose and 3,6-anhydrogalactose were the main components of the carrageenan and varied respectively between 53.79 and 63.79 mole %  for galactose and 31.69 and 41.41 mole % for 3,6-anhydrogalactose. The sulphates oscillated between 15 and 23% of carrageenan dry matter. I.R and NMR13C Spectra showed that the native phycocolloid extracted from H. musciformiswas formed by the repetition of the disaccharidic unit of kappa carrageenan.   Key words: Biology, carrageenans, chemical composition, pigments, Hypnea musciformis, seasonal variation.