Uv-blocking and hydrophobicity improvement of chitosan-based film with lignin addition from a pilot scale-up Organosolv process of Banana Pseudostem

Abstract

This study aims to analyze the potential use of modified lignin-rich material isolated from banana pseudostem as a green additive in chitosan-based film. Organosolv pulping lignin-rich material was chemically-modified with maleic anhydride, and then added to chitosan-based casting film at 2 and 5 wt% concentrations. The results showed that the molecular weight of lignin increased after chemical modification from 1974 to 2162 g mol^-1. The FTIR spectra also confirmed the chemical modification and showed CO stretching vibrations of carbonyl groups and a reduction in OH stretching vibrations present in aliphatic and phenolic structures. Although lignin has high thermal stability, no differences were observed after adding it to the chitosan matrix according to thermal analyses. However, lower tensile strength was identified with a reduction of up to 17.87 %. An increase of 10.06° in the water contact angle was observed after lignin incorporation, while water vapor permeability decreased by 14.4 % relative to the chitosan-based film. UV-blocking efficiency improved by up to 30.72 % and 50.30 % for films containing 2 wt% and 5 wt% lignin, respectively, compared to the control. All film samples showed an increased antioxidant capacity over 24 h, with maximum activity >34 %; however, no significant variation was attributed to the lignin addition. Overall, the results showed that the addition of esterified lignin at 5 wt% to chitosan-based film was the best formulation, improving mostly its UV-blocking capacity and hydrophobicity, which are valuable properties for industrial applications, such as food packaging.