Synthetic application and activity of cutinase in an aqueous, miniemulsion model system: Hexyl octanoate synthesis

Cutinase has been shown to be a promising biocatalyst for applications in processes targeted for industrial scale. This work aims to further contribute for highlighting such role, by bestowing detailed insight on the application of cutinase for the synthesis of value added compounds in miniemulsion environments (oil-in-water). The synthesis of hexyl octanoate was used as model system, due to the relevance of this compound for industrial applications as flavor and fragrance agent. The nature, specificity and selectivity of the catalyst enable operation under mild reaction conditions, without undesirable side reactions, leading to a very pure product. A high conversion yield, about 86%, for an enzyme concentration of 5 mg ml−1, was achieved.Hexyl octanoate synthesis and cutinase activity for different acid: alcohol molar ratio (R), under different pH environments, were evaluated. A maximum cutinase activity of 2.20 μmol mg−1 min−1 was observed for R = 0.5, which was tentatively ascribed to the stabilizing effect of hexanol on the miniemulsion. It is thus considered that the accumulation of the hydrophobic hexyl octanoate inside the droplets stabilize the miniemulsion system.

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► The application of cutinase on hexyl octanoate synthesis in a miniemulsion system was used to assess the influence of substrate influence on enzyme activity.
► A promising esterification yield (86%) for the synthesis of hexyl octanoate was achieved.
► Fluorescence spectroscopy showed a red shift due to the denaturation of the enzyme during time course of the esterification.
► The higher enzyme activity when an excess of hexanol was used confirms the stabilizing effect of the alcohol within the miniemulsion system environment.