Display omitted •Proanthocyanidin was used as covalent crosslinking agent of sericin/alginate blend.•PA-crosslinked sericin/alginate was used as matrix for ketoprofen extended release.•The obtained formulations presented gastro-resistant characteristic.•The particle with the lowest amount of PA showed ketoprofen extended release.•A complex release mechanism was associated to ketoprofen release. Sericin and alginate blend has shown good results for obtaining sustained release dosage forms. In the case of ketoprofen, it was necessary to resort to the use of the proanthocyanidin (PA) as crosslinking agent in order to achieve this same goal. Thus, various formulations were developed by adding different initial amounts of PA to the sericin and alginate blend with incorporated ketoprofen. The best results for drug loading, entrapment efficiency and release prolongation were obtained for the particle with the lowest amount of PA (0.5%). Mathematical modeling has indicated that different mechanisms may be involved in drug release, especially a complex release mechanism, with polymer dissolution and polymer chain relaxation allowing drug release. Particles characterization confirmed the incorporation of ketoprofen into the sericin, alginate and proanthocyanidin blend. It was verified that there was no interaction between them and there were no major changes in the physicochemical properties of the drug.