Ethylene scavenging properties from hydroxypropyl methylcellulose-TiO2 and gelatin-TiO2 nanocomposites on polyethylene supports for fruit application

Abstract

Several technologies have been proposed to preserve fruits and to avoid postharvest losses. The degradation of ethylene produced by the fruits using TiO2 photocatalysis has shown to be a good option to delay the ripening of fruits. This paper proposed a new application of biopolymers-TiO2 nanocomposites developed to extend the shelf-life of fruits. Photocatalytic coatings were applied on the expanded polyethylene foam nets to degrade ethylene. Gelatin and hydroxypropyl methylcellulose (HMPC) were tested as hydrophobic and hydrophilic matrices for the TiO2 incorporation. First, nanocomposite films prepared by casting were evaluated with regards to their photocatalytic properties. Both matrices, which were loaded with 1 wt% TiO2, degraded 40% of the ethylene injected in a batch reactor. By Langmuir-Hinshelwood model, ethylene degradation using gelatin-TiO2 films (kapp = 0.186 ± 0.021 min−1) was faster than the HPMC-TiO2 films (kapp = 0.034 ± 0.003 min−1). Then, gelatin-TiO2 dispersion was applied as a coating on the foam nets by dip coating. The gelatin-TiO2 bilayer exhibited higher concentration of ethylene degraded per photocatalytic area and photocatalyst mass unit (13.297 ± 0.178 ppmv m2gTiO2−1) than its film form (18.212 ± 1.157 ppmv m2gTiO2−1), which makes gelatin-TiO2/foam nets a promising composite design for fruit postharvest application.