Aqueous-rich flow intensification for enzymatic transesterification of rose geranium oil in a coiled flow inverter microreactor
5 affiliations
- 1Department of Chemical and Environmental Engineering
- 2University of Nottingham
- 3Department of Chemistry
- 4School of Chemical Engineering
- 5University of Adelaide
Abstract
Enzyme-assisted valorisation of crude floral oils into high-value fragrance esters is constrained by mass-transfer limitations and limited productivity in conventional batch reactors. Rose geranium oil, a naturally complex and terpene-rich multicomponent feedstock containing geraniol, citronellol and numerous other volatile constituents, was selected to investigate continuous enzymatic transesterification directly from a crude floral oil. Using Pseudomonas fluorescens lipase (PFL), geraniol and citronellol were selectively transesterified within the multicomponent oil, without prior isolation of these constituents. A process-intensified strategy was developed using a coiled flow inverter (CFI) microreactor. Aqueous-rich biphasic slug flow at an aqueous-to-organic ratio of 9:1, providing a specific interfacial area of 2319 m 2 m -3 , increased the apparent volumetric mass-transfer coefficient (kLa) by approximately 5-fold for geraniol and 7-fold for citronellol relative to batch operation. At 60 °C and a residence time of 5 min, the CFI achieved 99 % geraniol and 93 % citronellol conversion at 0.2 M rose geranium oil, while maintaining 91 % and 71 % conversion, respectively, at 1.4 M. Increasing the residence time to 7 min increased citronellol conversion at 1.4 M to 95 %. At 1.4 M, the 2 mL CFI provided calculated productivities of approximately 572 g day -1 for geranyl ester and 422 g day -1 for citronellyl ester, assuming continuous operation for 24 h. These results establish aqueous-rich segmented flow as an effective strategy for intensifying selective enzymatic transesterification within a compositionally complex terpene feedstock. The combination of selective conversion, enhanced interphase mass transfer and high calculated productivity provides a basis for the continuous valorisation of rose geranium oil and other complex floral oils into high-value fragrance esters.
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BibTeX
@misc{wikaputri2026aqueousrich,
title = {{Aqueous-rich flow intensification for enzymatic transesterification of rose geranium oil in a coiled flow inverter microreactor}},
author = {Alisa S Wikaputri and Shyam Rana and Rhea Satpute and Derek J Irvine and Robert A Stockman and Volker Hessel and Parimala Shivaprasad},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008471/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008471/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Aqueous-rich flow intensification for enzymatic transesterification of rose geranium oil in a coiled flow inverter microreactor
AU - Alisa S Wikaputri
AU - Shyam Rana
AU - Rhea Satpute
AU - Derek J Irvine
AU - Robert A Stockman
AU - Volker Hessel
AU - Parimala Shivaprasad
PY - 2026
DA - 2026/09/08
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008471/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008471/v1
AB - Enzyme-assisted valorisation of crude floral oils into high-value fragrance esters is constrained by mass-transfer limitations and limited productivity in conventional batch reactors. Rose geranium oil, a naturally complex and terpene-rich multicomponent feedstock containing geraniol, citronellol and numerous other volatile constituents, was selected to investigate continuous enzymatic transesterification directly from a crude floral oil. Using Pseudomonas fluorescens lipase (PFL), geraniol and citronellol were selectively transesterified within the multicomponent oil, without prior isolation of these constituents. A process-intensified strategy was developed using a coiled flow inverter (CFI) microreactor. Aqueous-rich biphasic slug flow at an aqueous-to-organic ratio of 9:1, providing a specific interfacial area of 2319 m 2 m -3 , increased the apparent volumetric mass-transfer coefficient (kLa) by approximately 5-fold for geraniol and 7-fold for citronellol relative to batch operation. At 60 °C and a residence time of 5 min, the CFI achieved 99 % geraniol and 93 % citronellol conversion at 0.2 M rose geranium oil, while maintaining 91 % and 71 % conversion, respectively, at 1.4 M. Increasing the residence time to 7 min increased citronellol conversion at 1.4 M to 95 %. At 1.4 M, the 2 mL CFI provided calculated productivities of approximately 572 g day -1 for geranyl ester and 422 g day -1 for citronellyl ester, assuming continuous operation for 24 h. These results establish aqueous-rich segmented flow as an effective strategy for intensifying selective enzymatic transesterification within a compositionally complex terpene feedstock. The combination of selective conversion, enhanced interphase mass transfer and high calculated productivity provides a basis for the continuous valorisation of rose geranium oil and other complex floral oils into high-value fragrance esters.
ER -