Sustainable bioactive pectin-based films to improve fruit safety via a circular economy approach

Abstract

This work reports on the valorisation of persimmon (Diospyros kaki Thunb.) for the development of food-grade antiviral coatings against major viral foodborne pathogens, human noroviruses (NoVs) and hepatitis A virus (HAV). Initially, the antiviral activity of polyphenol-rich pectin extracts with abundant non-covalent interactions (PPN), pectin extracts enriched with intact pectin-polyphenol ester and O-glycosyl bonds (PPC) and hydro-ethanolic polyphenol-rich extracts (EPE) was compared. Higher viral reductions were found for the pectin extracts rich in polyphenols, mainly in those containing covalent pectin-polyphenol interactions. This specific extract was mixed with commercial citrus pectin (CP) to develop active edible films. Dry films were analysed in terms of their optical, morphological, mechanical and barrier properties. Addition of the bioactive pectin persimmon extract resulted in more coloured films with lower transparency. The presence of covalently-linked polyphenols gave rise to stiffer films, with lower sorption capacity and more hydrophobic nature. The infectivity of MNV and HAV on fresh blueberries after the coating treatments was reduced by approximately 4.28 and 2.38 log, respectively, after overnight incubation, as compared to the controls, when 10% PPC was incorporated into the film. Higher amounts of PPC did not significantly improve the antiviral activity and a complete inactivation for both viruses was observed after 4 days of storage at 25 °C. This paper highlights the potential of persimmon discards as a cheap source of food-grade antiviral coatings with improved physicochemical properties as compared to commercial citrus pectin.