Optimization of the preparation for the agar oligosaccharides by enzymatic hydrolysis

The agar was obtained from Gracilaria lemaneiformis by water extraction. The optimal solvent-to-solid ratio,temperature and extraction time in the extration process were analysed by orthogonal test according to the yield of agar.Then the optimal p H value,hydrolysis temperature and substrate concentration in agar's enzymatic process were analysed by response surface method according to the degree of hydrolysis of agar.Result showed that the conditions containing solvent-to-solid ratio of 28∶1( v/w),temperature of 120 ℃ and extraction time of 90 minutes was found to be optimal for extraction of agar and the yield of agar was 32.8%. The condition cantaining p H value of 6.4,temperature of 54 ℃ and substrate concentration of0.6%( w/v) was found to be optimal for degrading agar and the degree of hydrolysis of agar was 89.75%. The products of enzymatic hydrolysis were determined as neoagarooligo saccharides with DPs of 2,4,6,and 8 by TLC,in which Neoagarotetraose was the major product,lay the foundation for the development and application of functional oligosaccharides agar.