Open Access

ARTICLE

Improving Antioxidant Properties of Chitosan Films by Incorporating Extracted Fractions of Propolis

by Clara Pastor, Chelo González-Martínez, Maite Cháfer, Amparo Chiralt^*

Instituto Universitario de Ingeniería de Alimentos (FoodUPV), Universitat Politècnica de València, Camino de Vera s/n, Valencia, 46022, España

* Corresponding Author: Amparo Chiralt. Email:

(This article belongs to the Special Issue: Special Issue in Celebration of JRM 10 Years)

Journal of Renewable Materials 2024, 12(12), 1949-1962. https://doi.org/10.32604/jrm.2024.056404

Received 22 July 2024; Accepted 23 September 2024; Issue published 20 December 2024

Abstract

Chitosan films with propolis aqueous extract were obtained in order to improve the antioxidant capacity of the materials. Likewise, oleic acid (OA) was also incorporated to enhance the film hydrophobicity, with and without previous infusion with propolis, to extract other potentially active compounds. The propolis extracts and the chitosan film-forming dispersions were characterised as to their particle size distribution, zeta potential and rheological behaviour. Chitosan-based films with aqueous extract and with oleic acid, containing or not propolis compounds, were obtained and characterised as to their microstructure, mechanical, barrier and optical properties and antioxidant capacity in order to evaluate their ability to extend the food shelf life. The propolis compounds from the aqueous extract notably modified the chitosan conformation and charge density of chitosan molecules, giving rise to more folded chains with a milder viscous effect. These changes in the polymer gave rise to a coarser film microstructure, which exhibited greater stiffness, and less stretchability and resistance to break, but a greater barrier capacity to water vapour and oxygen. These films had a ten-fold greater antioxidant capacity, thus having great potential to preserve food from oxidative spoilage. The incorporation of OA, containing or not propolis compounds, into these films reduced the film stiffness and resistance to break, and led to a highly enhanced oxygen permeability without there being any notable changes in either the water vapour barrier capacity or antioxidant power.

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