Silver Nanoparticles Entrapped in Zein Films as Biocompatible Coatings for Food Preservation
One of the main causes of large food losses is the cross-contamination of pathogenic microorganisms: Salmonella enterica and Listeria monocytogenes. Contamination is strictly connected to food processing lines, production lines and packaging [1]. In fact, it is required to find advanced systems able to deal with the problem [1]. To this aim, several studies and strategies are constantly proposed by the scientific community. One strategy is to develop release-based antimicrobial coatings, for example entrapping antimicrobial nanomaterials in biodegradable films.
Considering the well-known antimicrobial and anti-odor properties of silver nanoparticles (AgNPs) [2] and excellent filming properties of zein [3], in the present study we propose new coatings combining both components for the development of biodegradable and sustainable food packaging. Zein is a protein from corn, which has good hydrophobicity, and is a barrier material against humidity and gases [3]. AgNPs were prepared through a reduction process using a low amount of silver precursor, near ambient temperature for synthesis, and GRAS (generally recognized as safe) substances [4] as reducing agent (ascorbic acid) and stabilizer (citrate) [5]. As-prepared AgNPs were then properly added to zein solutions in order to obtain self-standing antimicrobial films. Transmission electron microscopy (TEM) images suggested a spheroidal morphology of AgNPs and an average size of about 30 nm. FTIR, XPS characterizations were carried out to investigate Ag loading into the films. The release of antimicrobial Ag ions was analyzed by electrothermal atomic absorption spectroscopy (ETAAS). Preliminary microbiological tests on the antimicrobial efficacy of the proposed films were performed. The perspective is to use these films as coatings for surfaces in real cases within the food industries.
Green Nanomaterials, biodegradable polymers, Zein Film, Antimicrobial Coatings, Food Packaging
A.V. Montefusco acknowledges funding by European Union –NextGenerationEU – NRRP Mission 4, Component 1. ProFood-IV Prodotti e processi innovativi per la filiera ortofrutticola della IV gamma (ARS01_00755) PON Ricerca e Innovazione 2014-2020 ASSE II - Azione II.2 project is acknowledged for funding.
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