## 4 Conclusions  
Kinetic and mass transfer studies demonstrated that Eversa(r) Transform 2.0, a low-cost commercial liquid lipase formulation, was preferentially adsorbed via reversible interactions (based on the mechanism of interfacial activation) inside the pores of PSty-DVB beads. A maximum immobilized protein amount of 31 mg:g\({}^{-1}\) was obtained after 480 min of contact time in a batch mode under mild experimental conditions \(-\)25 \({}^{\circ}\)C, 200 rpm at low ionic strength (5 mmol\(\cdot\)L\({}^{-1}\)) pH 5.0. The catalytic performance of immobilized lipase was examined in the production of flavor esters via direct esterification of octanoic with six different alcohols and compared with its soluble form. According to results, the heterogeneous biocatalyst provided, in general, better catalytic activity than soluble lipase due to excellent partition and diffusion of starting materials in its microenvironment under the experimental conditions used to perform this study. In fact, soluble lipase also exhibited good catalytic performance for reaction mixtures composed by fused oil and benzyl alcohol. However, all reaction systems using homogeneous catalyst (soluble lipase) led to an emulsification of the reaction systems that made downstream processes difficult (flavor esters separation). Reusability tests showed a drastic decrease of catalytic activity using highly polar alcohols (methanol and propanol) after consecutive batch reactions. On the other hand, the heterogeneous biocatalyst retained nearly 34% and 53% of its original activity after six successive batches using commercial isoamyl alcohol and fused oil, respectively. The latter is an interesting option due to its renewable nature, low-cost and easy acquisition in several countries. Environmental assessment studies demonstrated that the production of flavor esters in solvent-free systems catalyzed by immobilized lipase is a sustainable and eco-friendly process. This study confirms the promising application of immobilized lipase to catalyze biotransformation reactions in organic media (flavor esters production). Moreover, it also raises possibilities for new industrial applications of lipase Eversa(r) Transform 2.0, a commercial lipase used to produce biodiesel from waste oils on an industrial scale. Further studies should be conducted using fused oil as an alcohol source from bioethanol distilleries, evaluating the influence of relevant factors, including water molecules removal strategies that will improve the catalytic performance and operational stability of immobilized lipases on esters production in batch or continuous processes. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/catal12111412/s1](https://www.mdpi.com/article/10.3390/catal12111412/s1)]([https://www.mdpi.com/article/10.3390/catal12111412/s1](https://www.mdpi.com/article/10.3390/catal12111412/s1)), Figure S1: Illustration of the reaction mixture at equilibrium for esterification of fused oil and octanoic acid catalyzed by soluble lipase. Conceptualization, A.A.M. and R.F.-L.; methodology, J.M.J., F.R.M., G.R.C. and A.B.R.Z. ; software, A.A.M. ; validation, J.M.J., F.R.M., G.R.C. and A.B.R.Z. ; formal analysis, A.A.M. ; investigation, J.M.J., F.R.M., G.R.C. and A.B.R.Z. ; resources, J.M.J., F.R.M., G.R.C. and A.B.R.Z. ; data curation, J.M.J., F.R.M., G.R.C. and A.B.R.Z. ; writing--original draft preparation, J.M.J., F.R.M., G.R.C. and A.B.R.Z. ; writing--review and editing, A.A.M. and R.F.-L.; visualization, J.M.J., F.R.M., G.R.C. and A.B.R.Z. ; supervision, A.A.M. ; project administration, A.A.M. and R.F.-L.; funding acquisition, A.A.M. All authors have read and agreed to the published version of the manuscript. The present study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)--Brazil--Finance Code 001. The authors also thank the financial support of Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG)-- Brazil (Process APQ-01691-21).