No abstract

BACKGROUND: Sugar-based surfactants are highly relevant alternative ingredients for food grade formulations. Nevertheless, the design of sustainable manufacturing processes is still ongoing. RESULTS: Sorbitol ester surfactants were synthesized by lipase-catalyzed esterification in solvent-free conditions. Octanoic acid was dispersed in a 70 wt% sorbitol aqueous solution (containing the enzyme). The maximal conversion of 23.5 mole % of esterified fatty acid per mole of loaded fatty acid was obtained after 48 h in optimal conditions. The performance of the reactor was affected by both the nature and amount of the reactants and the dispersion state. Detailed structural analysis demonstrated that lipase from Candida rugosa specifically catalyzed the acylation of sorbitol on primary hydroxyl groups. Sorbitol esters accumulated exclusively in the oil phase, which led to easy and efficient product recovery. Oil phase containing the sorbitol esters could be used directly for preparing oil-in-water nanoemulsion without adding any other stabilizer. These nanoemulsions exhibited good stability after 7 days storage at 25 ∘ C or 60 ∘ C. CONCLUSION: A green manufacturing process for food grade oil-in-water nanoemulsions was designed involving a lipase-catalyzed esterification step which produced in situ the required surfactant. Nanoemulsions were prepared without using any other stabilizer. Biocatalyst reusabilityA reusability study of lipase was carried out by consecutive batch reactions with an initial load containing 0.94 g sorbitol (5.2 mmol), 1.487 g octanoic acid (1.25 mmol), 0.34 g lipase (AY Amano) and 400 L water. The total volume of the reaction medium was around

Formulation of submicronic diglyceride-in-water emulsions was carried-out without addition of synthetic surfactant in case of commercial caprylic/capric diglyceride. Sugar surfactant was prepared by contacting the oil with a concentrated aqueous solution of sorbitol (70 wt %) containing lipase AY. Interfacial lipase-catalyzed transesterification took place and led to limited but sufficient amounts of sorbitol ester and monoglyceride, which accumulated in the oil. The enzyme-treated oil could be easily separated from the aqueous phase and used for preparing oil-in-water emulsion without adding any other surfactant. A stable emulsion was obtained for at least 7 days and exhibited better stability at 60 °C than Tween 20-stabilized emulsion.