Chitin Oligosaccharide N,N′-Diacetylchitobiose (GlcNAc2) as Antimicrobial Coating against Listeria monocytogenes on Ready-to-Eat Shrimp (original) (raw)
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In vitro Effects of Chitosan on the Survival of Listeria monocytogenes
2016
1Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Ondokuz Mayis University, Samsun-TURKEY 2Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Erciyes University, Kayseri-TURKEY 3Department of Chemistry, Faculty of Science, Anadolu University, Eskişehir-TURKEY 4Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Ankara University Ankara-TURKEY
Iranian Journal of Public Health
Background: After cellulose, chitin is one of the most important polymers in crustaceans, insects, and fungi. Chitosan is one of the most important derivatives of chitin, which has important characteristics including degradability, non-toxicity, and biocompatibility antimicrobial and antioxidant properties. Methods: Chitosan was extracted from Penaeus semisulcatus shrimp using chemical methods and the degree of its austenitization was determined using a sub-red spectrophotometer and XRD. The nanoparticles were then synthesized using the ionic gelation method and analyzed through SEM. The antimicrobial effects of nanoparticles were also evaluated using antimicrobial tests on Listeria monocytogenes and Salmonella typhi. Results: Nanoparticles have antimicrobial activity and can inhibit bacterial growth at different concentrations. Conclusion: Chitosan nanoparticles have an inhibitory effect on Listeria monocytogenes, which is a gram-positive bacterium.
Inhibition of Listeria monocytogenes by a combination of chitosan and divergicin M35
The antimicrobial activities of the class IIa bacteriocin divergicin M35 and several types of chitosan against Listeria monocytogenes were quantified by agar diffusion, critical micro-dilution, and viable count and observed by electron microscopy. Antimicrobial activity of chitosan depended on its molecular mass (MM) and the pH. Three chitosans with MM values of 2, 20, and 100 kDa and 87.4% degree of deacetylation (DDA) were chosen for further study, based on high anti-listerial activity at pH 4.5. Electron microscopy suggested that the mechanism of anti-listerial activity also varied with the MM. Low-MM chitosan appeared to inhibit L. monocytogenes by affecting cell permeability and growth, whereas medium-and high-MM chitosan may form a barrier on the cell surface that prevents entry of nutrients. The minimum in-hibitory concentrations (MICs) of 2, 20, and 100 kDa chitosan and divergicin M35 against a divergicin-resistant strain of L. monocytogenes (LSD 535) were 2.5, 2.5, 0.625, and 0.25 mg/mL, respectively. The combination of any of these 3 chito-sans and divergicin M35 appeared to have an additive effect against L. monocytogenes, as determined by fractional inhibi-tory concentration (FIC) index. This study provides useful data for the development of chitosan films incorporating divergicin M35 for inhibiting L. monocytogenes in foods. Résumé : Les effets antimicrobiens de la divergicine M35, une bactériocine de classe IIa, et de plusieurs types de chito-sane envers Listeria monocytogenes ont e ´té quantifiés par la méthode de diffusion sur gélose, la méthode de dilution sur microplaques, le dénombrementdes cellules viables et par observation en microscopie e ´lectronique. L'activité antimicro-bienne des chitosanes dépendait de leur masse moléculaire (MM) et du pH. Trois chitosanes de 2, 20 et 100 kDa, déacéty-lés a ` 87.4 %, ont e ´té choisis dans les e ´tudes subséquentes, a ` cause de leur forte activité anti-listeria a ` pH 4.5. La microscopie e ´lectronique a suggéré que le mécanisme associé a ` l'activité anti-listeria variait aussi en fonction du MM. Le chitosane de faible MM semblait inhiber L. monocytogenes en affectant la perméabilité et la croissance cellulaires, alors que les chitosanes de MM moyenne ou e ´levée peuvent former une barrière a ` la surface de la cellule, empêchant ainsi l'entrée des nutriments. Les concentrations minimales inhibitrices (CMI) des chitosanes de 2, 20 et 100 kDa et de la diver-gicine M35 envers une souche de L. monocytogenes résistante a ` la divergicine (LSD 535) e ´taient de 2.5, 2.5, 0.625 et 0.25 mg/mL respectivement. La combinaison d'un des 3 chitosanes et de la divergicine M35 semblait avoir un effet additif en-vers L. monocytogenes, tel que déterminé par l'indice de concentration inhibitrice fractionnée « FIC index ». Cette e ´tude fournit des données utiles pour le développement de films de chitosane où la divergicine M35 est incorporée afin d'inhiber L. monocytogenes dans les aliments.
Food Control, 2020
The antimicrobial effects of nisin (2000 IU/mL) and grape seed extract (GSE, 1%) against Listeria monocytogenes (SSA184, SSA97 and LM10) inoculated on cooked shrimps (Litopenaeus vannamei) were investigated. Notable reductions (1.7–1.9 log CFU/g reduction) of L. monocytogenes were observed after 15-min treatment of combined nisin and GSE while SSA184 showed the highest susceptibility to the activity of nisin and GSE as compared to other strains. The atomic force microscopy results indicated that greater morphological changes were found in combination treated cells of SSA184, whose width (0.47 μm) and height (0.25 μm) were decreased while the surface roughness (10.12 nm) was increased significantly (P < 0.05). Residual nisin and GSE further inhibited the listerial growth during storage (0.4–0.8 log CFU/g increment). Based on the fitting goodness, Weibull and Baranyi models were verified as the best ones to describe inactivation kinetics of L. monocytogenes and growth dynamics during storage, respectively. Additionally, the colour of cooked shrimpsafter combined treatment were not negatively affected and even protected during storage. In conclusion, the antimicrobial treatment of combined nisin and GSE could be a potential antilisterial strategy for shrimps.