Biotechnological production of 2-phenylethanol from agroindustrial byproducts: experimental evaluation, techno-economic analysis, and life cycle assessment

Abstract

2-Phenylethanol (2-PE) is an alcohol with a rosy scent, commonly used as a fragrance, flavoring agent, and preservative in food and cosmetics. This study evaluates 2-PE bioproduction using apple pomace and whey as low-cost, biobased substrates for the growth of the yeast strain Kluyveromyces marxianus CBS600. Apple pomace resulted in the highest 2-PE productivity in shake flasks, reaching 44.5 mg.L⁻¹.h⁻¹-(1.07 g.L⁻¹ in 24 h), while its upscaling to a 1 L bioreactor led to 1.60 g.L⁻¹ in 48 h. Fermentation of acid whey supplemented with yeast extract and minerals for growth purposes significantly improved the bioconversion, leading to 2.64 g.L⁻¹ of 2-PE in 72 h. Using a membrane-based solvent extraction system, 2-PE was recovered efficiently from a glucose fermentation medium without impacting cell-specific product yield, showing promise for 2-PE recovery from waste-stream-based fermentation processes. The economic viability and environmental impacts of this process were also assessed based on process simulations of 2-PE fermentation at industrial scale. Techno-economic assessment showed that 2-PE production from whey was highly profitable, with a unit production cost of US$186 per kg and an internal rate of return of 24.9%. Life cycle analysis indicated that 2-PE fermentation has 1500 times lower greenhouse gas emissions than conventional 2-PE produced by extraction from roses. This study thus shows that the fermentative production of 2-PE is a sustainable and economically viable process that can contribute to a circular bioeconomy by valorizing agroindustrial residues.