Improvement of yield and quality of agar from Gracilaria edulis (Gmelin) Silva

摘要

Optimum levels of alkali/acid and thermal manipulations during extraction of agarudwere determined to increase the yield and quality of agar from red seaweed Gracilariaudedulis (Gmelin) Silva. Pre-soaking of dry weeds in water for 2 h increased the yieldudby 11.44%, but did not improve the gel strength. Pre-soaking for 12 h increased geludstrength and melting temperature considerably, but not the yield. Pre-soaking ofuddry weeds in 1.ON NaOH resulted in gel strength of 135 g.cm -2. Pre-soaking of driedudweeds with 0.5N and 1.ON HCl even at higher temperature showed improvementudneither in yield nor in the quality of agar and also resulted in hydrolysis of agar.udPretreatment at 2.0 - 3.0 N NaOH at 80°C for 1 hour to pre-soaked G.edulis for 11 hudin water proved to be the most ideal and optimum extraction procedure to obtainudhigher yield (14.16%), maximum gel strength (291g.cm lowest sulphate (0.732%)udand highest melting point (99°C) of agar.