Preparation of Alginate Oligosaccharides by Autoclaving Pretreatment Combined with Enzymatic Method

The enzymatic method is the primary focus for alginate oligosaccharide (AOS) production. However, the high viscosity of sodium alginate (SA) substrate often limits enzymatic efficiency. Pretreatment strategies aimed at reducing SA viscosity offer a promising and innovative solution to enhance process efficiency. This study compared the effects of three pretreatment methods-high-pressure vapor (HP-v), high-pressure solution (HP-s), and atmospheric-pressure air (AP-a)-on the physicochemical properties of SA. These pretreatments reduced SA viscosity and induced visible color changes in the order HP-v > HP-s > AP-a. Additionally, the effects of high-pressure treatments on molecular weight, M/G ratio, and chemical structure of SA were analyzed, confirming the feasibility of pretreatment-assisted enzymolysis. Molecular weight distribution and ESI-MS analysis of AOS after enzymolysis demonstrated that brief HP-v treatment maximizes the catalytic potential of alginate lyase, facilitating efficient AOS production without altering its structural characteristics.