Exploring the potential of biopolymers with fruit extracts nanoparticles on controlling food pathogens

Abstract

New polymeric materials development with functionalities that ensure safer andhealthier food is needed due to the threat of antibiotic resistance. This problem is associated with economic losses in the food industry, where bacteria food spoilage is one of the main factors responsible for reducing shelf life and increasing the risk of foodborne diseases, decreasing the productivity. The latest generation active nanoparticles development combining more than one antimicrobial agent in the same nanoparticle is a potentially powerful approach to combat antimicrobial resistance and biofilm-associated antimicrobial tolerance, as multiple cellular targets are engaged simultaneously. For this, a nanoparticle that combines biopolymers such as chitosan and lignin with fruit extracts into its structure can secure a tight interaction with the bacterial cell, increase bioactive uptake and work in synergy once materials changes improve particle properties based on smaller size and different charges that improve particles stability. Moreover, these materials are promising due to their chemical structure, which makes the nanoparticles formation easier, and biocompatibility, biodegradability, low cytotoxicity and mucoadhesive characteristics, making them potential to be used as polymeric active packaging. The use of these natural and environmental-friendly antimicrobials also represents a trend in the food industry as they are produced without the need for complex chemical synthesis processes and toxic chemicals, adding value to the materials that are industry spinoff. Recent results showed that chitosan/rhamnolipid nanoparticles are more effective in the control of Gram-positive pathogens when in acidic conditions. Thus, the combination of chitosan, lignin and grape extracts could be advantageous since many foods are acid. This research project aims to evaluate the antimicrobial potential of chitosan/lignin/grape extract nanoparticles against Staphylococcus aureus and Salmonella enterica both against planktonic bacteria and biofilms. Grape extracts from seeds and skin will be obtained, characterized by Gas Chromatography Mass Spectrometry (GC/MS) and their antioxidant activity will be evaluated by Folin-Ciocalteu and DPPH radical methods. Chitosan from two sources commercial (±-chitin) and obtained from squid-pens (²-chitin) will be compared and molecular weight and degree of acetylation will be determined by viscosimetry and 1H NMR spectroscopy. Lignin will be commercial and chitosan/lignin and chitosan/lignin/grape extract nanoparticles will be prepared using different parameters. Nanoparticles will be characterized by Fourier-Transform Infrared spectroscopy (FTIR), hydrodynamic size, zeta potential and Polydispersity Index (PDI) by Dynamic Lightscattering (DLS), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). Stability studies will be performed to verify the effect of pH and storage time. Nanoparticles will also be quantified by High-Performance Liquid Chromatography (HPLC). Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) ofeach substance against planktonic bacteria will be performed using the microdilution assay.Biofilms will be grown on peg lids to asses Minimum Biofilm Inhibitory Concentration (MBIC) and Minimum Biofilm Eradication Concentration (MBEC). Planktonic and biofilmviable cells will be quantified by colony forming units enumeration. Nanoparticles cellinteraction and viable cells in biofilms will be visualized by Confocal Laser Scanningmicroscopy (CLSM). The cytotoxicity effect of samples will be evaluated by the MTT assay.It is expected to understand and modulate the chemical and physical interactions between thecompounds, improve their properties and step up additional characteristics to thesenanoparticles, allowing increased the control of food pathogens. (AU)