Ultrasound-Assisted Enzymatic Synthesis of Fructose Oleic Ester using Supersaturated Fructose Solution

Fructose solubility is one of the major challenges inhibiting enzymatic synthesis of fatty acid sugar ester. Therefore, this study aims to define the optimal parameters for manufacturing fructose oleic ester (FOE) utilizing a supersaturated fructose solution coupled with ultrasound technology. Factors such as esterification time, ultrasound power, and substrate flow rate were evaluated. The reaction was carried out by adding the supersaturated fructose solution and oleic acid to the immobilized lipase in the jacketed fluidized bed reactor equipped with an ultrasound. FOE was evaluated based on ester concentration, ester bond, and emulsification properties. The results showed thatesterification activity of lipase was 36.45±9.95 U/g matrix. Fructose concentration in the supersaturated fructose solution was 12.30±2.33 mg/mL. The optimal parameters for synthesizing FOE were defined at 180 Watt and 0.2 mL/min for 180 min of reaction after one time using a series of esterification apparatus. FOE concentration was 85.13±9.56% and the sample with the best conditions had Rf value of 0.2 to ~0.8, wave absorption band for ester group (C=O) at wavenumber ~1712 cm -1 with a new peak (C-O bond) at 1373 cm -1 , emulsion capacity 99.86±0.01%, emulsion stability of 99.29±0.04%, and droplet size of 1.00 µm with non-uniform droplet size distribution (polydispersity index (PDI)=1.00).