| Summary: | In this study, the esterification reaction of lactic acid and ethanol was explored through application of commercial and customly produced enzymes for ethyl lactate manufacturing. Lipases produced from Candida rugosa were immobilized on different hydrophobic resins and were transferred into different organic phases that included polar (e.g. toluene, chloroform, ethyl acetate) and non-polar (e.g. hexane, decane) solvents, as well as citrus peel oils. Furthermore, the effect of a solvent-free system, where ethanol was used instead of organic solvents, varying substrate concentrations and control experiments conducted in the absence of enzymes were evaluated for their capacity to maximize the production of the ester. Lactic acid was inhibitory for the enzyme at concentrations higher than 0.1 M, while 88% and 75% conversion was obtained in chloroform and n-hexane respectively for lower acid contents. Finally, the study involves comparison of lipases from Candida rugosa to the commercially available Novozyme 435 employing lipases from Candida antarctica B, assessment of the hydrolytic activity for each of the enzymes tested as well as evaluation of the operational stability for the most efficient enzymes on the esterification reaction. The most efficient lipase in both case was the Novozyme 435. Even achieved evaluate whether the effect of the enzyme carrier in the production of ethyl lactate which demonstrated that ethyl lactase production is due solely to the enzyme. Finally, it was examined the functional stability assessment for the most efficient enzymes in the esterification reaction, where it was shown that there was no possibility of reused the biocatalyst in any of the cases considered. Overall, the development of the proposed bioprocess is feasible based on the concentration of ethyl lactate achieved, offering a new potential solution to the environmental problem of whey and an alternative route to the common industrial production of ethyl lactate through chemical synthesis. Στην παρούσα μελέτη, η ...
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