Optimization the process variables for the fractionation of Saccharina japonica to enhance glucan content

Saccharina japonica was fractionated by dilute sulfuric acid to increase the glucan content. The optimal fractionation conditions were determined as follows: reaction temperature 141.14 °C, reaction time 27.85 min and catalyst concentration 0.30%. The CCD model predicted 32.83% glucan content under these conditions. Experiments confirmed the maximum glucan content of 32.67% under the optimal reaction conditions, which was 4.7-fold higher than that of the raw S. japonica (6.95%). With the residual solid, an enzymatic digestibility of 89.38% was obtained using 15 FPU/g-glucan of cellulase enzyme loading, which was 2.6-fold higher than that of the raw S. japonica (34.85%).