Improvement of the barrier and mechanical properties of environmentally friendly mango kernel flour/glycerol films by varying the particle size of mango kernel flour

Abstract

The development of environmentally friendly films based on glycerol and different sizes of mango kernel flour particles (MKF), ranging from 100 to 600 µm, is reported. The casting solution method was used to produce the films, using distilled water as the solvent. The mechanical, morphological, barrier, surface, optical, wettability and biodegradability properties of the films were assessed. The mechanical analysis revealed that smaller particles lead to superior mechanical performance in terms of tensile strength, elastic modulus and elongation at break, achieving an elongation at break of 18.1 % for the films with the smallest particle size (100 µm). These results were confirmed by field emission scanning electron microscopy (FESEM) images of the films, where the gap between the mango kernel particles and the glycerol matrix is practically non-existent in films with the smallest particle size (100 µm). On the other hand, it was observed that as the particle size decreased, the barrier properties improved, showing a decrease in water vapor permeability rate (WVPR). With respect to antioxidant properties, it was observed that the films showed strong antioxidant activity, as assessed by 2,2–diphenyl–1–picrylhydrazyl (DPPH) inhibition above 90 % for all films after 1 week. Finally, MKF films proved to be completely biodegradable, with a 100 % of disintegration after 4 weeks of incubation time in compost soil, with the smallest MKF particle size films exhibiting the highest disintegration rate. • Smaller MKF particle size in the films leads to superior mechanical, barrier, antioxidant and biodegradability properties. • MKF/glycerol films possess strong antioxidant capabilities based on DPPH inhibition tests. • MKF/glycerol films present complete disintegration at 21 days of incubation in compost soil.