Ying YAN

Composition of the jury:

• Mr Romain KAPEL, Professor, University of Lorraine, Reviewer
• Mrs Loubna FIRDAOUS, Associate Professor, Université of Lille, Reviewer
• Mrs Laurence MUHR, Professor, University of Lorraine, Examiner
• Mr Giancarlo CRAVOTTO, Professor, University of Turin (Italy), Examiner
• Mrs Delphine PRADAL, Teacher-Researcher, ICAM, Examiner

Keywords: Food waste valorization, Sinapic acid, Adsorption chromatography, Membrane filtration, Solvent extraction in membrane contactor, Life cycle assessment

Abstract: Recovery of value-added compounds from agro-industrial by-products plays an important role in developing a sustainable bioeconomy. The by-product, mustard bran, has been reported as a promising source of phenolic compounds, particularly sinapine, a choline ester of sinapic acid (SA), accounting for approximately 80 % w/w of phenolic compounds, and that can be converted to free SA via hydrolysis. SA has been receiving increasing attention due to its attractive biological properties, such as antioxidant, anti-inflammatory, and antibacterial, making it a target for industrial valorization. However, reported studies have shown quite low SA content and purity (0.5 - 3.5 % w/w) in various mustard bran extracts, which highlights the need and challenge to study the purification of SA. This work evaluates the potential and efficiency of individual and combined separation process for the recovery of SA from mustard bran hydrolysate, focusing on technical performance and environmental footprint.

The first part of the work focuses on studying the purification of SA using adsorption chromatography process. Under static mode, the adsorption kinetics, equilibrium isotherms, and desorption test were studied on four macroporous adsorbent resins. The optimization of the dynamic process was performed on the best resin. The second part of the work studies the combination of membrane filtration and adsorption chromatography to enhance SA purity. The performances of two ultrafiltration (UF) and three nanofiltration (NF) membranes were evaluated and the suitable membranes were selected. Neither UF nor NF alone significantly increased SA purity but combining each with adsorption improved the adsorption results. The third part of the work focuses on SA recovery through solvent extraction in membrane contactor (MC) using cyclopentyl methyl ether as the organic phase, emphasizing mass transfer mechanisms and performance. The last part of the work analyses the environmental impact of the three laboratory-scale separation processes for SA recovery from mustard bran through an early-stage life cycle assessment.

Overall, this work improves the production processes for the bio-based SA and brings insights into their underlying mechanisms. Furthermore, it demonstrates the high potential of coupling processes for improved SA purity. These findings lay the groundwork for developing sustainable approaches for the recovery of SA that may apply to comparable phenolic compounds.