SORBITOL BEHENATE: ENVIRONMENTALLY FRIENDLY SYNTHESIS AND EVALUATION OF OLEOGELATION CAPACITY

Natural and biocompatible molecules capable of gelling oils have been intensely
researched, although they have limitations in terms of availability and technological
properties. In this sense, the biotechnological production of oleogelator is an excellent alternative, as it is a clean technology that enables the production of biocompatible ingredients. Gelling esters have been produced mainly with carbohydrates due to their abundance in nature, biocompatibility and relatively low cost, in addition to being subject to easy structural modification for the introduction of hydrophobic groups. Thus, the objective was to synthesize sorbitol esters (hydrophilic part) and behenic acid (hydrophobic part) through the action of lipase on acrylic resin L4777 in ethanol (food-grade solvent). A Plackett-Burman design with 8 runs and 4 central points was performed to identify the most critical variables for the synthesis reaction. Sorbitol-behenic acid molar ratio, temperature, agitation and solvent-water ratio as reaction medium were the evaluated variables. The condition with the highest conversion was chosen to evaluate the oleogelation capacity of the produced ester, which was named sorbitol behenate. Oleogels were prepared by the direct method in sunflower and linseed oils. Tilt test was used as a qualitative parameter to indicate whether there was oleogel formation and to determine the minimum gelation concentration (MGC). Results demonstrated that the solvent-water ratio was the critical factor in the synthesis. The highest conversion (>90%) was obtained without the presence of water, in the molar ratio 1:1, temperature of 60°C and agitation of 200 rpm. A reaction medium considered ideal for the production of carbohydrate esters must have the capacity to solubilize both the hydrophilic part and the lipophilic part. Thus, the high polarity difference between water and behenic acid limited the transport of behenic acid from the reaction medium to the enzyme vicinity and consequently reduced the conversion. Among the other determining variables, there was no statistically significant effect. In both tested oils, the MCG value was 10% (w/w). Enzymatic synthesis of sorbitol behenate has shown promise with high conversion using foodgrade reaction medium and no purification step. The new molecule also demonstrated the ability to form oleogel with lower MGC values than commercial carbohydrate esters.