Superior quality agar from red alga Gelidiella acerosa (Rhodophyta, Gelidiales) from Gujarat coast of India: An evaluation

Abstract

Physicochemical and rheological properties of agars extracted from 20 samples of Gelidiella acerosa collected from Gujarat coast in various seasons have been evaluated. The agar yields varied significantly (8.5–40.4%). The gel strength values were in the range of 200-700 g cm⁻² (1.5% gel at 20ºC) having gelling temperatures 36-41ºC. It was observed that agar obtained from Gelidiella acerosa of Okha, in almost all seasons has superior physicochemical and rheological properties than the rest of the samples. The 3,6-anhydrogalactose (3,6-AG) and sulphate content too varied significantly among the agar of each place. It was observed that the better quality agar has relatively lower sulphate and higher 3,6-anhydrogalactose contents. Therefore, Gelidiella acerosa of Okha can be used as a good source of agar. Rheological data of the best agar of the lot were also in good agreement with the other physicochemical data e.g., high gel strength agar showed higher G' value and vice versa.