Agar from the reproductive and vegetative stages of Gracilaria bursa-pastoris

Abstract

Native agar was extracted from cystocarpic, tetrasporic and vegetative plants of Gracilaria bursa-pastoris and the agar yield, gel strength, gelling temperature, intrinsic viscosity and 3,6-anhydro-l-galactose and sulfate content were analyzed. The results showed no significant differences in the agar yield and intrinsic viscosities at different reproductive stages. The vegetative plants showed higher gel strength agars than the carposporic and tetrasporic plants, but their gelling temperature was lower. The gel strengths and gelling temperatures were explained by the sulfate and 3,6-anhydro-l-galactose contents of the specimens. On the whole, the quality of the agar varied as a function of the reproductive stages. These results suggest that harvesting should be avoided during the main period of the reproductive stage of this seaweed.