Chitosan Coating Inhibits the Growth of Listeria monocytogenes and Extends the Shelf Life of Vacuum-Packed Pork Loins at 4 °C

An overview of the potential application of chitosan in meat and meat products

Chitosan is considered the second most ubiquitous polysaccharide next to cellulose. It has gained prominence in various industries including biomedicine, textile, pharmaceutical, cosmetic, and notably, the food industry over the last few decades. The polymer's continual attention within the food industry can be attributed to the increasing popularity of greener means of packaging and demand for foods incorporated with natural alternatives instead of synthetic additives. Its antioxidant, antimicrobial, and film-forming abilities reinforced by the polymer's biocompatible, biodegradable, and nontoxic nature have fostered its usage in food packaging and preservation. Microbial activity and lipid oxidation significantly influence the shelf-life of meat, resulting in unfavorable changes in nutritional and sensory properties during storage. In this review, the scientific studies published in recent years regarding potential applications of chitosan in meat products; and their effects on shelf-life extension and sensory properties are discussed. The utilization of chitosan in the form of films, coatings, and additives in meat products has supported the extension of shelf-life while inducing a positive impact on their organoleptic properties. The nature of chitosan and its compatibility with various materials make it an ideal biopolymer to be used in novel arenas of food technology.

Combined antibacterial effect of 460 nm light-emitting diode illumination and chitosan against Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes on fresh-cut melon, and the impact of combined treatment on fruit quality

This study evaluated the combined antibacterial effect of 460 nm LED illumination and chitosan on Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes on fresh-cut melon surface and its impact on the quality of melon at a total dose of 2.4 kJ/cm2 at 4 and 10 °C. Results showed that the antibacterial effect of LED illumination in combination with chitosan (0.5 and 1.0%) was much better than that of LED illumination alone, showing their synergistic effect. Among the pathogens, L. monocytogenes was the most susceptible pathogen to LED illumination. Although the color of melons became paler after LED illumination, there was little to no change in ascorbic acid content, total flavonoid content, or antioxidant capacity of the illuminated fruits compared with non-illuminated fruits. Thus, these results suggest that chitosan-mediated 460 nm LED illumination could be applied to inactivate foodborne pathogens on fresh-cut melons during storage at food establishments.

Verbascoside: An Efficient and Safe Natural Antibacterial Adjuvant for Preventing Bacterial Contamination of Fresh Meat

Inappropriate and disproportionate antibiotic use contributes immensely to the development of antibiotic resistance in bacterial species associated with food contamination. Therefore, alternative strategies to treat multidrug-resistant (MDR) bacterial infections are urgently needed. In this study, verbascoside was shown to exhibit excellent antibacterial activity and synergistic effects in combination with cell wall synthesis-inhibiting antibiotics, indicating that it can be used as an adjuvant to restore or increase the activity of antibiotics against resistant pathogens. In a mechanistic study, higher concentrations of verbascoside resulted in a longer lag phase and a lower specific exponential-phase growth rate of bacteria. Furthermore, verbascoside exerted its antimicrobial activity through multiple mechanisms, including cell membrane dysfunction, biofilm eradication and changes in cell morphology. The promising antibacterial activity and in vitro safety assessment results suggested that verbascoside can be used as a food additive for fresh meat preservation. Treatment with medium and high doses of verbascoside caused significant bacterial death in meat samples, slowed the spoilage rate, and extended the shelf life. Collectively, verbascoside is expected to be useful as an antibiotic adjuvant to prevent or treat resistant bacteria-related infections and an alternative novel antimicrobial additive in the food industry.

Evaluation of the Antimicrobial, Thermal, Mechanical, and Barrier Properties of Corn Starch-Chitosan Biodegradable Films Reinforced with Cellulose Nanocrystals

Packaging materials play an essential role in the preservation and marketing of food and other products. To improve their conservation capacity, antimicrobial agents that inhibit bacterial growth are used. Biopolymers such as starch and chitosan are a sustainable alternative for the generation of films for packaging that can also serve as a support for preservatives and antimicrobial agents. These substances can replace packaging of synthetic origin and maintain good functional properties to ensure the quality of food products. Films based on a mixture of corn starch and chitosan were developed by the casting method and the effect of incorporating cellulose nanocrystals (CNC) at different concentrations (0 to 10% w/w) was studied. The effect of the incorporation of CNC on the rheological, mechanical, thermal and barrier properties, as well as the antimicrobial activity of nanocomposite films, was evaluated. A significant modification of the functional and antimicrobial properties of the starch–chitosan films was observed with an increase in the concentration of nanomaterials. The films with CNC in a range of 0.5 to 5% presented the best performance. In line with the physicochemical characteristics which are desired in antimicrobial materials, this study can serve as a guide for the development this type of packaging for food use.

Antimicrobial effect of insect chitosan on Salmonella Typhimurium, Escherichia coli O157:H7 and Listeria monocytogenes survival

The antimicrobial capability of chitosan from Tenebrio molitor as compared with chitosan from crustacean (Penaeus monodon) on different pathogenic microorganisms of concern in food safety was studied. The antimicrobial effect was tested at pH 5 and pH 6.2 and at two different initial concentrations (10³ or 10⁶ CFU/mL). Results indicated that chitosan from both sources have antimicrobial activity, although the effect depended on the microorganism considered (Salmonella Typhimurium, Listeria monocytogenes and Escherichia coli O157:H7). Our results indicated that Salmonella was the most resistant bacteria, and that chitosan from insect was less active than chitosan from crustacean, especially against Salmonella. Another important factor on antimicrobial activity was the pH of the sample. When chitosan was added to a solution with a pH of 6.2 it was more active against Listeria and Escherichia coli, than at pH 5.00. Besides, the effect of chitosan appears to decrease with the incubation time, since some increases in counts were observed on E. coli and Salmonella after the 24 and 49 hours of incubation.

Rainbow trout fillet biopreservation by edible chitosan-based coating containing egg yolk antibody (IgY) and lycopene

The aim of the study was to investigate the effect of the extracted egg yolk antibody along with lycopene on the chemical quality of the rainbow trout fillet during 16 days of refrigeration storage. Chickens were immunized against Pseudomonas fluorescens (P. fluorescens), Shewanella putrefaciens (S. putrefaciens) and total spoilage bacteria and their eggs were collected for the isolation of egg yolk antibodies. Then fish fillets were immersed in chitosan-based coating solutions, containing lycopene and extracted antibodies, and analyzed for lipid oxidation changes (peroxide, thiobarbituric acid, free fatty acid and fatty acid profile), physico-chemical properties (pH and water holding capacity), and sensory evaluation, during 16 days of refrigeration storage. Results showed that chitosan solutions with lycopene or IgY could significantly (p < 0.05) increase the oxidative stability of lipids in fish fillets; although, combinational use of lycopene and IgY showed a higher effect on delaying the rate of lipid oxidation. Significant differences were also observed between treatments contained combination of chitosan, antibody and lycopene with the control group, regarding pH and WHC. Saturated fatty acids increased in all treatments, although the changes in the treatments containing lycopene and antibody were significantly (p < 0.05) lower than the control group. Hence the addition of egg yolk antibody and lycopene in coating solution are good bio-preservatives for seafood products as it improves sensory attributes and prevents lipid oxidation.