AbstractThe lipid binding capacity of chitosan (partially deacetylated chitin) was determinined with respect to micellar solutions of bile salts, dodecyl sulfate, natural ox bile and an artificial mixed microemulsion. The stoichiometry was determined following the separation of the solid phase by filtration or centrifugation. The major variables in the extent of binding were the pH and ionic strength, suggesting that the interactions are mainly of ionic nature. It is noteworthy that under optimal conditions chitosan could bind, i.e., coprecipitate, with 4–5 times of its weight with all the lipid aggregates tested. These results have a bearing on the nutritional and pharmacological applications of chitosan. The analyses of the components from the precipitates with microemulsion and ox bile show a significant selectivily of binding caused by hydrophobic interactions.