earticle

영어

In this study, a novel sugar fatty acid ester (SFAE), maltoheptaose-palmitate ester (G7-PA), was synthesized using commercially available 3 lipases, free or immobilized form, as catalysts. The central composite design of RSM based on three-factor (DMSO concentration, the molar ratio of substrates, and enzyme amount) at five-level was used to optimize the G7-PA synthesis. Among these lipases, the immobilized CALB with the greatest esterification/hydrolysis activity ratio was the best enzyme for the G7-PA synthesis. The optimal conditions for achieving 92.75% conversion yield was determined as 10% DMSO, 0.2 of G7/PA molar ratio, 1g of the immobilized CALB per 0.128 g of PA at 60°C for 24 h. G7-based sugar esters using capric (C10:0), lauric (C12:0), myristic (C14:0) acid as substrates were also synthesized at the same optimal condition. Among the G7-FAEs, G7-PA exhibited improved properties as a biosurfactant in O/W emulsion compared with a commercial sucrose-PA (S-PA). However, emulsions prepared with the other G7-FAEs were unstable at pH 7. At the low surfactant concentration (0.1%), G7-PA emulsion exhibited a droplet distribution similar to 0.2% surfactant condition, while S-PA emulsion was quickly destabilized. Intriguingly, the G7-PA showed better emulsifying properties than the S-PA at the acidic condition (pH 3). Flocculation and phase separation observed at the S-PA emulsion, but that of G7-PA was stable for 7-day. In thermostability tests, G7-PA and S-PA both were stable at the pasteurization and the boiling treatment. Conclusively, the novel bio-surfactant G7-PA could expand the application fields of sugar esters based on its superior properties.