SEAFOODplus: Lipid extraction from sardine by-products

Scientific Alert Note

Innovative marine lipid extraction developed and applied on sardine by-products

Upgrading by-products from the seafood industry is one of the main targets in the SEAFOODplus project PROPEPHEALTH. The research described in the present Scientific Alert Note was performed as a part of a Ph.D. study. The thesis was recently presented and defended successfully. The developed process is a combination of enzymatic hydrolysis and ultra-filtration, which has made it possible to extract healthy marine lipids from sardine by-products from the surimi process in an effective way.

Authors: Joop Luten, Fiskeriforskning, Norway, and Justine Dumay, Ifremer, France.

: Jean Pascal Bergé and Justine Dumay

Seafood is a rich source of healthy lipids. Small fatty pelagic fish species, like sardines (Sardina pilchardus) with a low commercial value, are being used more and more in the surimi production as an alternative for Alaska pollack and blue whiting.

Upgrading of the by-products such as heads, viscera and washing water from the sardine based surimi production is necessary. In addition, the interest of the feed and food industries for marine lipids is becoming more and more important. Extraction of the marine lipids is often carried out along two ways. The first one is solvent consuming and the second one requires high temperature treatments and could induce structure oxidation of the poly-unsaturated fatty acids (PUFA).

Justine Dumay, Ifremer, Nantes, has recently finished her Ph.D. thesis regarding marine lipid extraction using mild procedures with low energy consumption and investment. On October she defended her thesis with success in public. Jean Pascal Bergé, Ifremer, involved in PROPEPHEALTH was one of her supervisors in collaboration with Pascal Jaouen and Gilles Barnathan form the University of Nantes, France. RTD Pillar 4 coordinator, Joop Luten, Fiskeriforskning, and participant in PROPEPHEALTH, Patrick Bourseau, University of Bretagne, were members of the Ph.D. exam committee.

In her work hydrolysis and ultra-filtration techniques have been investigated. Firstly, the exogenous proteolytic enzymes Protamex, Alcalase and Flavourzyme were selected for hydrolysis. The optimal conditions for an efficient use in a model substrate system were established taking into account various variables like temperature, pH and costs. The optimal conditions (pH 8, 50°C) were used in the rest of the experimental work. It is shown that a long hydrolysis time is needed to obtain a high degree of hydrolysis of the solid sardine by-products. However a long hydrolysis time does not lead to the most efficient recovery of the lipids from the sardine head by-products. Although in some cases a multi-enzyme hydrolysis gives a slight improvement in yield the higher costs due to the price of the enzymes do not justify this approach, is the conclusion.

A lower degree of hydrolysis obtained for sardine viscera hydrolysis is probably due to the antagonistic effect of endogenous enzymes. However inactivation of the endogenous enzymes does not lead to improvement.

The various aspects of concentrating marine lipids in the retentate and peptides transmitted to the permeate by ultra filtration have been covered in the thesis. Choices of the Molecular Weight Cut Off and cleaning procedures of the membranes have been studied. It is shown that first concentration and then dia-filtration was the best procedure in terms of short time and small water volume needed. Also the quality of the products, being lipids, phospholipids and fatty acids, was best under these conditions.

The thesis of Justine Dumay is entitled ‘Extraction de lipides en voie aqueuse par bioreacteur enzymatique combine à l’ultrafiltration: application à la valorisation de co-produits de poisson (Sardina Pilchardus)’ contains a very extensive literature review and all chapters are summarized in English. The thesis can be ordered as a pdf file from Justine Dumay ( justine.dumay(at)gmail.com) or from Jean Pascal ( jpberge(at)ifremer.fr).