Worldwide, there are a large number of retailers in popular markets offering fresh orange juice, which is preferred for its nutritional and health value. Incorrect management during the preparation, the presence of pests, and inadequate environmental conditions can affect the microbiological quality of the juices sold in popular markets and can even make them a reservoir for enteropathogenic bacteria. The aim of this study was to evaluate the microbiological quality and presence of enteropathogenic bacteria in freshly prepared orange juice sold in popular markets, by quantifying the fungi, yeasts, aerobic mesophilic bacteria, and total and fecal coliforms. The fecal colonies were subjected to tests to confirm the presence of enteropathogenic bacteria. The results showed that none of the juice sold at popular markets had fungi, while all of them had yeasts, mesophilic bacteria, and total coliforms, and only 14% did not present fecal coliforms. The identification of the fecal bacteria was positive for E. coli and Salmonella. The microbiological quality of the orange juices sold in popular markets needs to be improved, since the high microbial load makes them a health risk.

Non-pasteurized juices may contain microorganisms that cause spoilage and public health problems. Owing to their physical properties, dielectric barrier discharge plasmas show high efficiency in the inactivation of microorganisms; in this study, coliforms, Escherichia coli and Salmonella spp. were identified in samples of orange juice collected from street stalls. Microbiological inactivation in orange juice was analyzed using the Weibull model. Using optical emission spectroscopy, the oxidant particles responsible for the inactivation of bacteria are observed. The 200 mL samples were treated for 2.5, 3.5, 5.0, and 6.0 min using a plasma with electrical power of 40 W. It was observed that for aerobic mesophilic, the colony-forming units were reduced from 4.47 to 1.00 Log; for coliforms, from 4.00 to 1.00 Log; and for yeast, from 4.75 to 3.18 Log. The evaluated physicochemical parameters indicate that there are no significant changes in the properties of the juice; therefore, the interaction process with dielectric barrier discharge is a technique that has viability in the inactivation of microorganisms and offers an alternative for the food industry in treating juices.

Foodborne diseases are a serious public health problem worldwide, frequently caused by bacterial pathogens, many of these microorganisms are capable of protecting themselves from unfavorable environmental conditions by forming a biofilm, which allows them to colonize successfully inert surfaces and living substrates, such as edible fruits. The objective of this study was to evaluate the formation of biofilms by Escherichia coli of different origins, using the microtiter technique, which allows measuring the Optical Densities (OD) produced by the adhesion of bacterial communities to the surfaces, we evaluated a total of 12 E. coli strains, using two different culture media (minimum essential medium with glucose and Bertanni broth) and 24, 48 and 72 hours of incubation. The results showed that the strains differed in their biofilm production levels, with no difference between the two-culture media, reaching its maximum production level at 72 hours. Once the biofilm production results were obtained, the E. coli-producing strains, serotype O157:H7 and 93300 157:H7, were subjected in the laboratory to a bacterial adhesion test on the epidermis of tomato fruits (Solanum lycopersicumL. ) in order to obtain OD, an acetic-curing silicone-based well was designed, which allowed the microtiter technique to be used accurately; when favorable results were obtained, the study was set up under greenhouse conditions, simulating the natural form of these bacteria to reach the fruits still cultivated, the results showed that both strains form biofilms in the tomato fruits, both in green and ripe fruits, greenhouse conditions provide microenvironmental advantages to the bacteria capable of protecting them from external conditions, including the cleaning and disinfection, which could increase its incidence and morbidity.