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Recently, the research on innovative food packaging has been oriented toward biodegradable materials to lower the environmental impact generated by conventional plastics. The films often carry functional additives interacting with the matrix and modifying its physical properties. In this work tannin, a scarcely exploited active additive, was used to obtain potato starch-based films, and its content was optimized on the basis of mechanical and microscopic tests. Rheological measurements were adopted to evaluate the tannin-starch interaction and the microstructure of the film forming solutions (FFSs). Their thickness, color, thermal conductivity, elastic modulus (E el ), elongation at break (EAB), surface wettability and water solubility were evaluated. Furthermore, microstructure was investigated through Fourier-transform infrared spectroscopy (FTIR), polarized light (POM) and scanning electron microscopy (SEM). It was observed that all FFSs behave as weak gels and tannin addition weakens the gel structure and decreases the gelatinization temperature from about 60 °C to 57 °C. Plastic and deformable films (E el  = 1.96 MPa and EAB = 189 %) were obtained at low tannin fractions, whereas, at a higher concentration, stiffer films (E el  = 12 MPa and EAB = 10 %), with hydrophobic behavior were produced. Among the tested tannin fractions, an intermediate value of 1.7 % (w/w) was found to be promising for industrial purposes., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Proteins are widely used in the formation and stabilization of multiphase systems, thanks to their ability to adsorb at the interface reducing the interfacial tension and promoting the formation of viscoelastic layers. Owing to the growing consumer demand, the food industry is moving toward the growing use of plant-based proteins, suitable for consumers who do not eat products of animal origin, for either ethical or health reasons. Nevertheless, the scientific literature lacks information on the surface activity and emulsifying ability of these proteins. In this work, the interfacial properties of soy, hemp and brown rice isolate proteins were investigated at the interface with commercial sunflower oil (O/W) to evaluate their characteristics in view of potential uses in food applications such as emulsions, sauces, dressing, topping and soft foods. Dilatational and shear kinematic, with pendant drop and magnetic rod techniques, respectively, were used. The dilatational analysis was performed in static and dynamic conditions, to obtain the equilibrium adsorption isotherms and the rheological parameters of the interfacial layers under both oscillation and stress relaxation. The interfaces were studied in shear conditions with small amplitude oscillations and creep tests. The obtained results evidenced that all tested proteins are able to build a strong viscoelastic layer with properties comparable to those of animal proteins. Brown rice protein seems particularly effective in reducing the interfacial tension even if shear tests evidence that the interface is weaker than that obtained using hemp or soy protein. Hemp protein seems very promising for potential practical uses yielding intermediate interfacial tensions and strong viscoelastic layers., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Noemi Baldino reports financial support was provided by University of Calabria., (Copyright © 2022 Elsevier B.V. All rights reserved.)