Processing and characterization of chitosan films with incorporation of ethanolic extract from “pequi” peels

Abstract

Chitosan is a polysaccharide with excellent film forming ability widely evaluated as active packaging and edible coatings. Chitosan has good antimicrobial activity in gel form; however, in a solid state (film format), a reduction in this activity can occur due to spatial arrangement of the chains in the polymer matrix. Small amounts of natural compounds could then be added to the film formulations to improve both antifungal and antibacterial properties. One possible additive is the “pequi” (Caryocar brasiliense Comb.) peel ethanolic extract (PPE), which forms homogenous blend with chitosan and has proved antimicrobial activity. In this study the preparation of chitosan-PPE was evaluated concerning the effect promoted in the film structure due PPE incorporation. Films processed by casting were analyzed by Fourier transform infrared spectroscopy (FTIR), microscopy, X-ray diffraction, mechanical and thermal properties, water vapor permeability (WVP) and surface wettability. FTIR analysis indicates interactions between the phenolic compounds in the extract and the hydroxyl and amine groups present in the chitosan structure, by establishing a possible ester bonding between constituents. The presence of PPE resulted in a decrease of WVP and an increasing in hydrophobicity. The extract addition also reduced the film’s crystallinity along with a slight decrease of plasticity and lowering of the initial polymeric degradation temperature. However, the blend was characterized by a homogeneous matrix with smooth topography. The results suggest that PPE has good compatibility with chitosan, introducing small changes that do not alter the potential for medical or foodstuff applications.