A. Mouradi-givernaud et al., Biology and agar composition of Gelidium sesquipedale harvested along the Atlantic coast of Morocco, HYDROBIOL, 399, 1999, pp. 391-395
Gelidium sesquipedale (Clem.) Bornet et Thuret is the main raw material use
d for agar production in Morocco. The biology and biochemistry of this slow
growing alga collected monthly over one year has been studied. The agar co
ntent varied around 40% of algal dry weight and reached a maximum of 44.5%
in November. Agar gel strength was maximum in May and July (1000 g cm(-2)),
and melting (90 degrees C) and gelling (35 degrees C) temperatures varied
slightly. The agar contained a high 3,6-anhydrogalactose content (40-45 mol
%) and low amounts of 6-O-methylgalactose (around 1 mol%) and sulphate (1.0
-1.6% of dry weight). The reproductive status of the alga affected the agar
synthesis and quality. The phycocolloid gel strength was related to the me
an polysaccharide chain length but not to its chemical substitution.