Supercritical CO2 technology applied to the production of flavor ester compounds through lipase-catalyzed reaction: A review

The demand for fresh and natural products is increasing worldwide. Therefore, new production methods of natural flavor compounds have attracted the attention of food manufacturers. In this scenario, biocatalyzed chemical synthesis is being explored as an alternative to produce flavoring compounds with application in the chemical and food industries. The use of supercritical carbon dioxide (SC-CO2) as the reaction medium in biocatalytic processes enhances the transport properties of substrates in the active site of enzymes, increasing the reaction's conversion. SC-CO2 has some operational advantages, such as tunability of their properties (density, viscosity, and solubility) and moderate critical conditions (Pc = 7.38 MPa and Tc = 31.05 degrees C). Besides, these pressure and temperature conditions are in the range of stability of most lipases. Nevertheless, the use of co-solvents, reuse of catalyst, nature of lipases (free or immobilized) and pressurization/depressurization steps need to be evaluated in the biocatalyzed production of flavoring compounds in SC-CO2. Careful evaluation of these parameters is necessary to obtain an optimal ratio between enzyme/substrates/solvents. In this work, the use of supercritical carbon dioxide (SC-CO2) for the biocatalyzed chemical synthesis of flavor esters using lipases as a catalyst is reviewed.