[Thesis defence] 16/12/23, Yosra Belghith: "Eco-extraction of high added-value biomolecules from olive pomace" (SQPOV)

Title of the thesis

Eco-extraction of high added-value biomolecules from olive pomace

Date and place

16 December 2023 at 11 a.m., Faculté des Sciences de Sfax, Tunisia

Discipline

Chemistry

Laboratory

MicroNut, UMR408 SQPOV

Framing

• Ms Valérie TOMAO
• Mr. Noureddine ALLOUCHE

Composition of the jury

• MRS. RAOUDHA MEZGHANI JARRAYA: PROFESSOR (FSS) : PRESIDENT
• MR. MICHEL TREILHOU: PROFESSOR (INU CHAMPOLLION): RAPPORTEUR
• MR. MHAMED BEN MESSAOUDA: SENIOR LECTURER (IPEST): RAPPORTEUR
• MR. FAKHER CHABCHOUB: PROFESSOR (FSS): EXAMINER
• MRS. VALERIE TOMAO : LECTURER HDR (AU) : THESIS DIRECTOR
• MR. NOUREDDINE ALLOUCHE: PROFESSOR (FSS) : THESIS SUPERVISOR

Summary of the thesis

Olive pomace is the main by-product of the olive oil extraction process. Although harmful to the environment, olive pomace is a potential source of natural molecules that are beneficial to human health. Part of our work was devoted to characterising an ethanolic extract of olive pomace. UPLC/MS analysis enabled us to identify 59 secondary metabolites, the most abundant of which were hydroxytyrosol, tyrosol, oleuropein aglycone, oleoside, caffeic acid and p-coumaric acid. Biological tests showed that the ethanolic extract had antioxidant, anti-diabetic and analgesic activity. The second part focused on optimising extraction yields of olive pomace polyphenols using eco-responsible extraction technologies. This work led us to conclude that optimal extraction conditions were obtained for a ratio of (60/40) (EtOH/H2O) using the accelerated solvent extraction process. In the final section, a new approach was developed to optimise the extraction of phenolic compounds using vegetable oils as the extraction solvent. Based on a complete factorial design with three factors (type of oil, temperature and extraction technique), we were able to show that the optimum conditions for extracting polyphenols from pomace were ultrasound-assisted extraction in olive oil at 65°C.

Key words Olive pomace, polyphenols, LC/MS, biological activities, accelerated solvent extraction, ultrasound-assisted extraction, microwave-assisted extraction, microbeads, conventional maceration, full factorial design