The kinetics to redefine green flavours and fragrances: solvent-free, enzyme-assisted transesterification of rose geranium oil using wool-immobilised Pseudomonas fluorescens lipase

We introduce a solvent-free transesterification of rose geranium oil using wool-immobilised Pseudomonas fluorescens lipase (WPFL) as a greener and more sustainable alternative to conventional ester synthesis. Targeting the United Nations’ 12th Sustainable Development Goal and aligning with green chemistry principles, the system eliminates solvents, designs an inherently safer process, and utilizes nature's own catalysts: enzymes. WPFL demonstrates catalytic efficiency comparable to Novozym 435, a widely used commercial lipase, while offering a significant cost advantage. Characterisation through ESEM and CLSM imaging confirms that wool provides a uniform enzyme distribution, enhancing both catalytic efficiency and structural stability. The system achieves full conversion of geraniol in five hours and 88% conversion of citronellol, effectively doubling productivity compared to solvent-based systems. The final ester yields are independent of rose geranium oil concentration, underscoring the robustness of the system for processing real flower waste oils which is an essential feature for industrial applications. Sensory analysis showed the enzymatic modification enhanced the fragrance profile by intensifying floral and fruity notes while removing undesirable herbal undertones. Finally, we present a novel parallel Ping pong bi-bi mechanism incorporating specificity constants (kcat/KM) that describes the parallel reactions of citronellol and geraniol, providing a robust framework for comparing enzyme efficiency and selectivity in terpene ester production from diverse floral waste streams. This work establishes WPFL as a cost-effective, scalable, and sustainable alternative to traditional lipases, with transformative potential for industrial terpene ester synthesis.