Institution: | a Departamento de Oceanografia e Limnologia, Laboratório de Macroalgas, UFRN, Praia de Mãe Luiza s/n 59014-100, Natal, RN, Brazil b Lab. Phys. Mol. Struct., Falculté de Pharmacie, 15 av. C. Flahault, 34060, Montpellier Cedex 2, France |
Abstract: | The effect of season on yield and physical properties of agars extracted from Gracia gracilis and G. bursa-pastoris were determined. The agar yield from G. gracilis was maximum during spring (30%) and minimum during autumn (19%). In G. bursa-pastoris, the agar yield was greatest in summer (36%) and lowest in winter (23%). Agar yield from G. bursa-pastoris was positively correlated with temperature (r=0.94; P<0.01) and salinity (r=0.97; P<0.01) and negatively with nitrogen content (r=?0.93; P<0.01). Agar gel strengths fluctuated from 229 to 828 g cm?2 and 23 to 168 g cm?2 for G. gracilis and G. bursa-pastoris, respectively. The gelling temperature showed significant seasonal variation for both species. Chemical analysis of agar from the two seaweeds indicated variation in 3,6-anhydrogalactose and sulfate content (P<0.01). Furthermore, there was an inverse correlation between the two chemical variables. In general, agar extracted from G. gracilis possessed better qualities than agar extracted from G. bursa-pastoris and can be considered a candidate for industrial use. |