Comparative effect of physical and chemical treatments on the mechanical and barrier properties of Bambara groundnut-based protein-lipid films

Aim: Increased awareness of environmentally friendly and biodegradable packaging materials and the need to reduce negative and harmful interactions of food with packaging materials have driven research efforts towards edible packaging using combinations of food-based polymeric substances. Such edible packaging materials, including protein-based, carbohydrate-based, lipid-based compounds and their combinations, have revolutionised packaging perception. In this study, protein-lipid films produced from the extract obtained via hydrothermal treatment of Bambara groundnut flour were essentially modified. Methods: The effects of chemical modification (using formaldehyde as a cross-linking agent) and exposure to ultraviolet (UV) light on the film-forming solutions were investigated. Films from the modified and pure solutions were analysed for their barrier and mechanical properties, including water vapour permeability and elongation at break, among others. Also colour parameters of the protein-lipid films were examined. Results: The findings revealed that the values for mechanical and barrier properties of the formed films were comparable to those of other composite films, and also presented an improvement over polysaccharide, protein, or lipid-only films. The film formation rate ranged from 2.92 ± 0.03 to 4.43 ± 0.03 g/10 min, while the film yield ranged from 5.46 ± 0.07 to 8.92 ± 0.02 g/100 mL. Water vapour permeability of the Bambara groundnut films ranged from 0.49–0.63 gm–1s–1Pa–1. The films had high opacity values. Elongation at break values for the UV-modified film (44.37) were higher than those of the unmodified film (43.07). Conclusions: The Bambara groundnut films had better mechanical strength compared to the reference soybean film. This indicates a possible use in the coating of brittle and light-sensitive foods.