Polyphenols from Olea europaea L. cv. Caiazzana leaf pruning waste for antioxidant and UV-blocking starch-based plastic films

Olive tree waste products, such as leaves, can be used to formulate antioxidant additive mixtures for bioactive and functional packaging. In this context, with the aim of better enhancing the flavonoid component, the extract obtained by ultrasonic accelerated maceration was fractionated to obtain the OlP fraction, characterized by UltraViolet-Visible (UV-Vis) and Attenuated Total Reflectance Fourier Transform InfraRed (ATR FT-IR) spectroscopic techniques and chromatographic analysis coupled to high-resolution tandem mass spectrometry. The extract, consisting of 60.4 % flavonoids, exhibited a marked antiradical capacity but did not exert cytotoxic effects. The incorporation, at two different percentage levels, in a starch-based film, already with the plasticizers glycerol and sorbitol, was previously characterized chemically by ATR FT-IR tools, morphologically by Scanning Electron Microscopy (SEM), for the thermal behaviour and physical-chemical properties of thickness, density, water vapor transmission rate, moisture absorption, and colour. The data obtained, including the assessment of the UV-blocking, photoprotective, and antiradical activities, emphasize that the composition of the film was maintained, with OlP preserving its antioxidant efficacy while also acting more effectively as a moisture absorber and natural plasticizer.