Extraction de lipides en voie aqueuse par bioréacteur enzymatique combine à l'ultrafiltration : application a la valorisation de co-produits de poisson (Sardina pilchardus)

The main goal of this work was to up-grade sardine (Sardina pilchardus) by-products using mild procedure, environmentally sound, in order to obtain valuable compounds involving moderate investment and low energy consumption. Hydrolysis and ultrafiltration techniques have been investigated. Firstly, selected enzymes have been calibrated in order to determine their optimal conditions with a model substrate and to permit the comparison between them. Then, hydrolysis on sardine head and viscera have been carried out in two steps. The first one had the objective to determine the enzyme efficiency and the study area. The second step was to optimise enzymatic hydrolysis using experimental designs. The aim of this second step was to obtain the highest lipid recovery in the liquid fractions using the variation of the influents hydrolysis parameters such as temperature, hydrolysis time and enzyme concentration. The soluble phase obtained after this optimised step have been filtered using ultrafiltration technique in order to separate lipids from peptides. Lipids from sardine by-products have been mainly recovered in the liquid fractions of the hydrolysates. Moreover, aqueous fraction has shown a high content of phospholipids. W3 fatty acids represent around 20% of the total fatty acids into those fractions. Regarding viscera, which is a hardly crushing matrix, the lipid extraction yields have been improved using enzymatic treatment compared to traditional extraction. The ultrafiltration treatment of the soluble phase has allowed, after the determination of operating conditions, to separate lipids from peptides and to concentrate the phospholipids in the retentate.