Superior quality agar from Gracilaria species (Gracilariales, Rhodophyta) collected from the Gulf of Mannar, India

Gracilaria edulis, G. crassa, G. foliifera, and G. corticata are naturally occurring agarophytes of Indian waters. These agarophytes were evaluated for their agar contents using an improved process recently reported by us (US Patent 2005/0267296A1). The effect of different concentrations of NaOH in the alkali treatment was studied for optimizing the extraction conditions. These Gracilaria species of Indian waters produced agars, both native and alkali treated, with different properties confirming the heterogeneity of the agar polymers in this genera, as one would expect. Among these, G. edulis and G. crassa produced agar polymers having high gel strengths of 490 +/- 8.16 and 800 +/- 15.4 g cm(-2), respectively, with 8% NaOH treatment as opposed the low gel strength agars that have been reported in the literature to date.