Anti-Salmonella A, B and D monoclonal antibody

Gold nanoparticles capped with chitosan (CH-NGs), glycol chitosan (GC-NGs) and poly(gamma-glutamic acid) (PANGs) were synthesized separately, characterized and evaluated for catalytic and antibacterial activities. Surface Plasmon resonance peak at 520-530 nm confirmed the formation of NGs, while FTIR spectra revealed the involvement of hydroxyl, amine and amide groups in biopolymers on NGs formation and coating. Particle size, zeta potential and surface coating were respectively 21.7 nm, +50.2 mV and 20% for CH-NGs, 5.6 nm, +46.5 mV and 43.5% for GC-NGs and 7.4 nm, -37.3 mV and 34.5% for PA-NGs. Compared to citrate-capped NGs (CT-NGs), biopolymer-capped NGs exhibited high catalytic activity in a 4-nitrophenol reduction model with the pseudo first-order catalytic rate for PA-NGs being 4-6 fold higher than CH-NGs and GC-NGs. No significant antibacterial effect was shown for CT-NGs. However, PA-NGs was superior to gentamycin in inhibiting Salmonella enterica and Escherichia coli-O157:H7, while CH-NGs and GC-NGs showed the highest antibacterial effect against Listeria monocytogenes, followed by Salmonella enterica, Escherichia coli-O157:H7, methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus. TEM images showed that GC-NGs were attached on MRSA surface to alter cell permeability, block nutrient flow and disrupt cell membrane, whereas PA-NGs penetrated into Salmonella enterica to generate cavities, plasmolysis and disintegration. (c) 2020 Elsevier B.V. All rights reserved.

Among the non-thermal food technologies, high pressure processing (HPP) is currently the most widespread intervention in the juice industry. The study herein was conducted to challenge a wide range of pressure (401-599 MPa) and dwell time (87-313 s) in orange juice processing. The parameters were combined and targeted a minimum of 5-log cycle reductions in a cocktail for the pathogens of reference -Escherichia coliO157:H7,Salmonella entericaeListeria monocytogenes- inoculated into the juice. Eleven trials were carried out based on a central composite rotational design. All combinations of pressure and dwell time succeeded in reducing all pathogens.E. coliO157:H7 exhibited more resistance to HPP thanS. entericaandL. monocytogenes. The findings demonstrated that relatively low pressure (similar to 400 MPa) and short dwell time (similar to 200 s) can be successfully used to produce a safe orange juice.