Chitosan and gelatin materials incorporated with phenolic extracts of grape seed and jabuticaba peel: Rheological, physicochemical, antioxidant, antimicrobial and barrier properties

In this study, chitosan and gelatin materials incorporated with grape seed (Vitis vinifera L.) (VSE) and jabuticaba peel (Plinia cauliflora) (PPE) extracts were developed with potential application as food coatings. It was evaluated how the concentration of the extracts and their addition order in the polymeric matrix affect its properties. Samples with VSE presented a higher total phenolic content and also a more elastic behavior than samples with PPE. The addition order effect over viscosity was the opposite for the extracts, and for the samples with VSE a lower viscosity was obtained when the extract was added before gelatin. All samples were hydrophilic, a good result for application as coatings. Films with PPE were less soluble than chitosan/gelatin film, and CG5P sample was chosen as the most suitable for the desired application, due to its lower water vapor permeation value. The microbial permeation test showed that all samples avoid microorganism growth, extending shelf life of food. The results of this study revealed the extracts concentration was the main factor which influenced the studied parameters; however, their addition order had significant importance on rheological and barrier properties, the ones most influenced by the availability of extract compounds in the polymeric system.

Keywords: Antioxidant; Chitosan; Edible films; Gelatin; Grape seed; Jabuticaba peel.