How the temperature and salt content of food simulant affect the release of tyrosol or phenolic acids from bioactive films?

Abstract

Active films made of chitosan and fish gelatin blends containing 5% (w/wt of polymers) of tyrosol, ferulic acid or caffeic acid were prepared by the casting method. The kinetic of release was assessed in water or in 1% (w/v) NaCl solution, at three temperatures (4, 25 and 32°C). Partition (Kf/S) and the effective diffusivity (D) was modelled which allowed to characterize the release mechanism. Tyrosol has a faster release at a higher concentration than the other antioxidants, because of its structure and a lower level of intermolecular interactions with the biopolymer matrix. There is less effect of temperature and of the salt content on the release of tyrosol contrarily to the phenolic acids. The NaCl solution (food simulant) induced conformational changes in the biopolymer network due to the modifications of the interactions between the gelatin, chitosan and antioxidants, inducing a less strengthen network and a faster release.