2017 (11): "Study of the interactions polysaccharides - antimicrobial biomolecules of protein nature : application to the development of microcapsules and active films for food preservation" (thesis by Chédia BEN AMARA)

Read the thesis online

Thesis supervision:

Dr Adem GHARSALLAOUI, Pr Pascal DEGRAEVE
 

• Funding:

Scholarship from the Ministry of Higher Education and Research
 

• Doctoral school :

EDISS (Interdisciplinary Doctoral School for Health Sciences), ED n ° 405, Université Claude Bernard Lyon 1

This work deals with the development of encapsulation systems based on polysaccharides and antimicrobial molecules of protein nature such as hen egg-white lysozyme and nisin produced by Lactococcus lactis. Complex coacervation of alginate or pectin (two anionic polysaccharides) with lysozyme or nisin, positively charged over a wide range of pH, would be a solution to protect these molecules and ensure their controlled release during food preservation. The used polysaccharides were chosen according to their sensitivity to the enzymes produced by the targeted bacteria. The whole of this work performed at various levels showed (i) the impact of some physicochemical factors (ratio, pH, ionic strength,…) on the interactions between lysozyme or nisin and alginate or pectin, (ii) the influence of these factors on the properties of the formed complexes, and (iii) the role of the selected polysaccharides in stabilizing the structure of lysozyme or nisin during spray-drying. Finally, the structure and the antimicrobial activity of films produced by casting and microcapsules obtained by spray-drying were studied in relation to the properties of the formed complexes. This work makes it possible to contribute to a better understanding of the various mechanisms implied in the formation of peptide/polysaccharide or protein/polysaccharide complexes, their resistance to spray-drying and their ability to protect and release active molecules.