Structure and properties of three alginates from Madagascar seacoast algae

Three original alginates extracted from Madagascar seacoast algae are purified and characterized. Especially, a protocol for isolation of pure alginate is proposed including EDTA to obtain a good yield of recovery. The main characteristics of alginates are given (M/G ratios, average molecular weight) and discussed in relation with their origin. At end, gels are formed in presence of calcium excess and their rheological moduli are compared and related to the M/G ratios.