Development of active films utilizing antioxidant compounds obtained from tomato and lemon by-products for use in food packaging

This study focused on the recovery of antioxidant compounds from lemon and tomato by-products for use as natural additives in the development of active food packaging formulated using three different polymeric matrices that included low-density polyethylene (LDPE), polylactic acid (PLA), and G-polymer (GP). The films were characterized according to chemical-physical, thermal analyses, and their barrier and mechanical properties. Migration assays were performed to evaluate the release of active compounds from polymeric matrices, which were quantified in the food simulant by high-performance liquid chromatography with a diode array detector and then confirmed via liquid chromatography coupled to mass spectrometry. The antioxidant capacities of the films were determined to evaluate their applicability for use as antioxidant-active packaging. The incorporation of extracts into polymers resulted in different structural changes and enhanced properties according to the nature of the polymeric matrix based on the interactions of the –OH groups of polyphenols and the chemical groups of the polymers. The lemon (LE) and tomato (TE) extracts lead to a substantial improvement in water barrier properties of PLA and GP-based films. The active PLA and GP films released high amounts of polyphenolic compounds (up to 65% for GP containing LE); mainly hesperidin and eriocitrin for LE films, and chrologenic acid for TE films. PLA loaded with lemon extract at 4% was selected as the most suitable for use as antioxidant packaging to extend the shelf-life of foods with high fat contentL. Barbosa-Pereira is grateful to the Spanish Ministry of Science, Innovation and Universities for her “Juan de la Cierva-Incorporación” Grant (Agreement No. IJCI-2017-31665). C. H. Barbosa is grateful for her research grant in the frame of the VIPACFood project (ARIMNET2/0003/2016) and for the Ph.D. Grant 2021.08154.BD from the Fundação para a Ciência e Tecnologia (FCT), PortugalS