Optimization of one-step enzymatic hydrolysis conditions for two large brown algae and analysis of the antioxidant activity of the hydrolysis products

Background The industrial production of alginate lyase provides high-quality tool enzymes for the enzymatic hydrolysis of large brown algae. Establishing a seaweed enzymatic hydrolysis process that is simple to operate while offering both high enzymatic hydrolysis efficiency and a high yield of oligosaccharides contributes to the high-value utilization of large brown algae. Results A one-step enzymatic hydrolysis process combining alginate lyase, pectinase and cellulase was adopted to conduct enzymatic hydrolysis experiments on Sargassum horneri and Saccharina japonica, respectively. The Box-Behnken experimental design was applied to optimize the dosage of the three enzymes, as well as the temperature, pH and reaction time of enzymatic hydrolysis. The results showed that the optimal enzymatic hydrolysis conditions for S. horneri were as follows: alginate lyase 490 U/g, pectinase 4660 U/g, cellulase 380 U/g, hydrolysis temperature 47°C, hydrolysis pH 5.5 and hydrolysis time 8 h. For S. japonica , the optimal enzymatic hydrolysis conditions were alginate lyase 360 U/g, pectinase 5000 U/g, cellulase 284 U/g, hydrolysis temperature 49.5°C, hydrolysis pH 5.2 and hydrolysis time 8.8 h. After process optimization, the solid hydrolysis rates of S. horneri powder and S. japonica powder were increased to 71.4% and 66.3%, respectively, and the proportion of low-molecular-weight alginate oligosaccharides (DP < 6) in the hydrolysates reached approximately 70%; both enzymatic hydrolysates exhibited favorable antioxidant activity according to the detection. Conclusions The findings of this study greatly simplify the technological process for preparing alginate oligosaccharides via brown algae enzymatic hydrolysis and significantly improve the production efficiency. How to cite: Shi K, Dong Y, Wang Q, et al. Optimization of one-step enzymatic hydrolysis conditions for two large brown algae and analysis of the antioxidant activity of the hydrolysis products. Electron J Biotechnol 2026;83. https://doi.org/10.1016/j.ejbt.2026.100722 .