Physical and Chemical Properties of Agar from a New Member of Gracilaria, G. lemaneiformis (Gracilariales, Rhodophyta) in Japan

Abstract

Agars of Gracilaria lemaneiformis, a new member of Gracilaria in Japan, were extracted by the alkali treatment method with various concentrations of NaOH (1, 3, 5, 7, 9%) at 80°C. The treated samples were incubated for 1, 2, and 3 hours. Agar gel strength, gel deformation, and apparent Young's modulus were measured, and showed excellent gel characteristics. The highest gel strength of 1706.8±164.0 g/cm2 was obtained from 1% agar of 3% NaOH, 3 h treatment, with gel deformation of 9.9±0.9mm, and apparent Young's modulus of 171.7±1.1 g/mm, compared with the other treatments in this study. Agar solutions of this seaweed could form a firm gel at the very low concentration of 0.5% agar. Sulfate and 3,6-anhydro-L-galactose contents reached the highest value of 4.4% from non-alkali treated agar, and 48.1% from 3% NaOH, 3 h treated agar, respectively. The methoxyl contents attained the highest value (1%) in non-alkali treated agar and 1% NaOH, 1 h treated agar. The agar of G. lemaneiformis showed an essentially higher gel strength compared with the Japanese commercial grade agars. © 1995, The Japanese Society of Fisheries Science. All rights reserved.