Many raw vegetables, such as tomato, chili, onion, lettuce, arugula, spinach, and cilantro, are incorporated into fresh dishes including ready-to-eat salads and sauces. The consumption of these foods confers a high nutritional value to the human diet. However, the number of foodborne outbreaks associated with fresh produce has been increasing, withEscherichia colibeing the most common pathogen associated with them. In humans, pathogenicE. colistrains cause diarrhea, hemorrhagic colitis, hemolytic uremic syndrome, and other indications. Vegetables can be contaminated withE. coliat any point from pre- to postharvest. This bacterium is able to survive in many environmental conditions due to a variety of mechanisms, such as adhesion to surfaces and internalization in fresh products, thereby limiting the usefulness of conventional processing and chemical sanitizing methods used by the food industry. The aim of this review is to provide a general description of the behavior and importance of pathogenicE. coliin ready-to-eat vegetable dishes. This information can contribute to the development of effective control measures for enhancing food safety.

Quorum sensing (QS) is a process of cell–cell communication for bacteria such as E. coli and Salmonella that cause foodborne diseases, with the production, release, and detection of autoinducer (AI) molecules that participate in the regulation of virulence genes. All of these proteins are useful in coordinating collective behavior, the expression of virulence factors, and the pathogenicity of Gram-negative bacteria. In this work, we review the natural or synthetic inhibitor molecules of QS that inactivate the autoinducer and block QS regulatory proteins in E. coli and Salmonella. Furthermore, we describe mechanisms of QS inhibitors (QSIs) that act as competitive inhibitors, being a useful tool for preventing virulence gene expression through the downregulation of AI-2 production pathways and the disruption of signal uptake. In addition, we showed that QSIs have negative regulatory activity of genes related to bacterial biofilm formation on clinical artifacts, which confirms the therapeutic potential of QSIs in the control of infectious pathogens. Finally, we discuss resistance to QSIs, the design of next-generation QSIs, and how these molecules can be leveraged to provide a new antivirulence therapy to combat diseases caused by E. coli or Salmonella.

Strawberries are highly consumed around the world; however, the post-harvest shelf life is a market challenge to mitigate. It is necessary to guarantee the taste, color, and nutritional value of the fruit for a prolonged period of time. In this work, a nanocoating based on chitosan and ZnO nanoparticles for the preservation of strawberries was developed and examined. The chitosan was obtained from residual shrimp skeletons using the chemical method, and the ZnO nanoparticles were synthesized by the close-spaced sublimation method. X-ray diffraction, scanning electron microscopy, electron dispersion analysis, transmission electron microscopy, and infrared spectroscopy were used to characterize the hybrid coating. The spaghetti-like ZnO nanoparticles presented the typical wurtzite structure, which was uniformly distributed into the chitosan matrix, as observed by the elemental mapping. Measurements of color, texture, pH, titratable acidity, humidity content, and microbiological tests were performed for the strawberries coated with the Chitosan/ZnO hybrid coating, which was uniformly impregnated on the strawberries’ surface. After eight days of storage, the fruit maintained a fresh appearance. The microbial load was reduced because of the synergistic effect between chitosan and ZnO nanoparticles. Global results confirm that coated strawberries are suitable for human consumption.

Microencapsulates of ethanolic extracts of Renealmia alpinia (Rottb.) Maas fruit pericarp were obtained by spray drying. Physicochemical properties (pH, °Bx, titratable acidity, maturity index, moisture content and color), bioactive compounds (anthocyanins and other phenolic compounds) and antioxidant capacity of the fresh fruit pericarp were assessed. Microencapsulates were produced by feeding a 1:3 mixtures of ethanolic extracts (encapsulated material) and different encapsulating agents (maltodextrin, gum arabic and a 1:1 mixture of both) to the spray dryer. Physical properties (yield, particle size, moisture, color, wettability, bulk and compact densities) of the resulting powders were determined while both stability of antioxidant compounds and maintenance of antioxidant capacity were evaluated during a 28-day storage at 4 and 25 °C. Fresh pericarp was an important source of phenolic compounds and anthocyanins which heavily contributed to fruit color parameters. The highest yield 21.58% and moisture content 2.45% were observed in powders with 1:1 maltodextrin-gum arabic ratio. Gum arabic microencapsulates better preserved anthocyanins (10.37 ± 2.38, 11.65 ± 0.58, mg Cyd-3-Glu/g) and phenolic (7.58 ± 0.51, 8.70 ± 1.28 mg GAE/g) at both storage temperatures 4 and 25 °C, respectively. Two individual anthocyanins were identified by HPLC: cyanidin-3-O-glucoside and delphinidin-3-O-glucoside. While maltodextrin capsules exhibited increased stability of antioxidant compounds and activity at 4 °C storage. Evaluated microencapsulates might represent a suitable alternative as a natural coloring agent with potential antioxidant activity.

The demand for healthier meat products is increasing remarkably and natural antimicrobial agents such as essential oils (EOs) are required, which can be applied in the vapor phase. For this experiment, the effectiveness of essential oils of oregano, thyme, and orange in the vapor phase on the microbiological and sensory characteristics of sausages inoculated with Salmonella enterica and stored at 4°C during 72 hrs and 144 hrs, were studied. Oregano EO with 2000 ppm was the most effective treatment against Salmonella enterica with a logarithmic reduction of 1.97 Log10 CFU/g compared to thyme 1.36 Log10 CFU/g and orange 1 Log10 CFU/g) after 144 hrs. In relation to the general acceptance level, the meat product exposed to the orange EO in vapor phase presented the highest approval by the judges nevertheless, however, were the ones that showed the least reduction in the microbial population. Finally, the results showed that the addition of essential oil in the vapor phase to meat products exerted a bactericidal effect with higher EOs concentrations and some also caused alterations in the sensorial properties of the product.