Wet steam method for reducing attached cells of Salmonella and Listeria monocytogenes on Hass avocado.

The consumption of avocados and their products has been linked to outbreaks of illness caused by Salmonella enterica and Listeria monocytogenes. These pathogens have been isolated from avocados collected from farms and markets. After contact with the avocado epicarp, the cells of Salmonella and L. monocytogenes can become loosely attached (LA) by suspension in a film of water and attraction by electrostatic forces, or strongly attached (SA) by physical and irreversible attachment mechanisms. Attached cells may have greater resistance to agents used to decontaminate the fruit. The effect of applying wet steam (WS) to the epicarp of Hass avocados on the reduction LA and SA counts of Salmonella and L. monocytogenes was evaluated as a function of the exposure time. The inoculated avocados were washed and exposed to WS for 30, 45, and 60 s inside a treatment chamber. Salmonella was found to be more susceptible to WS than L. monocytogenes. The efficacy of steam in reducing LA and SA cell numbers was similar for both pathogens. Steaming avocados for 60 s reduced LA Salmonella and L. monocytogenes cells by 4.6 and 4.8 log CFU/avocado, whereas SA cells were decreased by 5.2 and 4.4 log CFU/avocado, respectively.•Steaming the avocados for 60 s produced the greatest reduction in loosely and strongly attached cells for both pathogens.•Wet steam treatment efficiently eliminated the loosely and strongly attached cells of both pathogens.•The Listeria monocytogenes attached cells showed greater resistance to steam treatment than Salmonella.

Effect of storage temperature and time on the behavior of Salmonella, Listeria monocytogenes, and background microbiota on whole fresh avocados (Persea americana var Hass).

Avocados are popular fruits; however, contamination of whole fresh avocados and avocado products with foodborne pathogens has raised concern about their safety. Recalls and import alerts of avocado products due to contamination with Listeria monocytogenes cause important economic losses. The behavior of Salmonella, L. monocytogenes, and background microbiota on whole fresh avocados at 5 and 25 °C as affected by temperature and time of storage was investigated. Whole fresh avocados were inoculated by immersion in suspensions containing six rifampicin-resistant strains of Salmonella or L. monocytogenes, and stored at 5 °C for 48 d, or at 25 °C for 11 d. At selected sampling times, avocados were removed from storage and pathogens enumerated. The log counts of both pathogens at each temperature were fitted to the Weibull distribution nonlinear model to estimate kinetic parameters including the time for the first 1-log reduction (δ), the shape of the curve (ρ), and the time for two (2-D) and three (3-D) log reductions. Salmonella and L. monocytogenes initial populations (approx. 7 log CFU/avocado) decreased during storage at 5 and 25 °C; L. monocytogenes mean counts were higher than those observed for Salmonella (P < 0.05). L. monocytogenes showed a lower rate of decline at 5 °C when compared to Salmonella. In general, the ability of both pathogens to survive on the surface of avocados stored at room temperature was similar. Salmonella and L. monocytogenes counts decline over time on the epicarp of whole avocados; however, if the initial number of cells is large enough, the pathogens could be present for large periods of time. Simultaneously, psychrotrophic microorganisms (PM), aerobic plate count (APC), coliforms (C) and yeasts/molds (Y/M) were enumerated from non-inoculated avocados stored at 5 and 25 °C. Initial mean counts for PM, APC, C and Y/M ranged from 6.1 to 6.6 log CFU/avocado and showed no change (P > 0.05) during storage at both temperatures. Good agricultural and handling practices from farm to fork are crucial to prevent or minimize contamination of whole avocados; otherwise, if large numbers of pathogens contaminate the fruit, they could survive and be transferred to the pulp, or to other ready to eat foods, representing a risk for consumers.

Second Version of a Mini-Survey to Evaluate Food Intake Quality (Mini-ECCA v.2): Reproducibility and Ability to Identify Dietary Patterns in University Students.

Evaluation of food intake quality using validated tools makes it possible to give individuals or populations recommendations for improving their diet. This study's objective was to evaluate the reproducibility and ability to identify dietary patterns of the second version of the Mini Food Intake Quality Survey (Mini-ECCA v.2). The survey was administered using a remote voting system on two occasions with four-week intervals between administrations to 276 health science students (average age = 20.1 ± 3.1 years; 68% women). We then performed a per-question weighted kappa calculation, a cluster analysis, an ANOVA test by questionnaire item and between identified clusters, and a discriminant analysis. Moderate to excellent agreement was observed (weighted κ = 0.422-0.662). The cluster analysis identified three groups, and the discriminant analysis obtained three classification functions (85.9% of cases were correctly classified): group 1 (19.9%) was characterized by higher intake of water, vegetables, fruit, fats, oilseeds/avocado, meat and legumes (healthy food intake); group 2 (47.1%) frequently consumed both fish and unhealthy fats (habits in need of improvement); group 3 (33%) frequently consumed sweetened beverages, foods not prepared at home, processed foods, refined cereals and alcohol (unhealthy food intake). In conclusion, the Mini-ECCA v.2 has moderate to excellent agreement, and it is able to identify dietary patterns in university students.

Salmonella, Listeria monocytogenes, and Indicator Microorganisms on Hass Avocados Sold at Retail Markets in Guadalajara, Mexico.

Hass avocados may become contaminated with Salmonella and Listeria monocytogenes at the farm and the packing facility or later during transportation and at retail. In Mexico, avocados are frequently sold in bulk at retail markets, where they are stored at room temperature for several hours or days and exposed to potential sources of microorganisms. These conditions may favor the entry, adhesion, survival, and biofilm formation of Salmonella and L. monocytogenes. The aim of this study was to determine the occurrence of Salmonella, L. monocytogenes, and other Listeria species and the levels of indicator microorganisms on the surface of avocados sold at retail markets. A total of 450 samples (Persea americana var. Hass) were acquired from retail markets located in Guadalajara, Mexico. One group of 225 samples was evaluated for the presence of Salmonella and for enumeration of aerobic plate counts, yeasts and molds, Enterobacteriaceae, coliforms, and Escherichia coli. The other 225 samples were processed for isolation of L. monocytogenes and other Listeria species. Microbial counts (log CFU per avocado) were 4.3 to 9.0 for aerobic plate counts, 3.3 to 7.1 for yeasts and molds, 3.3 to 8.2 for Enterobacteriaceae, 3.3 to 8.4 for coliforms, and 3.3 to 6.2 for E. coli. Eight samples (3.5%) were positive for Salmonella. Listeria spp. and L. monocytogenes were detected in 31 (13.8%) and 18 (8.0%) of 225 samples, respectively. Listeria innocua, Listeria welshimeri, and Listeria grayi were isolated from 7.6, 1.3, and 0.9% of samples. These results indicate that avocados may carry countable levels of microorganisms and could be a vehicle for transmission of Salmonella and L. monocytogenes.

Food Consumer Behavior and Salmonella Exposure Self-Perception in the Central Region of Mexico.

In Mexico, there is limited information regarding food consumer behaviors at home. The knowledge of food consumption and food handling practices can help to determine more realistically the exposure to different hazards, such as Salmonella spp. on the population. The main goal of this study was to characterize the food consumption habits of five food groups (fruits and vegetables, fresh meat, dairy products, processed meat products, and seafood), food handling practices, and Salmonella exposure self-perception of the population of the central region of Mexico using an online survey. A total of 1,199 surveys were analyzed. The group of fruits and vegetables is the most consumed and one of the most related to the consumer self-perception of suffering from salmonellosis. Mexican consumers regularly use refrigeration as the principal food storage method for the five food groups (42.2% to 90.8%), and generally, they store the products between 2 and 3 days (26.5% to 38.1%). A total of 86.4% of consumers reported that they always wash their hands prior to food preparation. A total of 16.9% and 13.0% use the same cutting board and knife, respectively, to cut more than one product without applying sanitization. Men, people between 20 and 24 years, and people between 60 and 64 years, had the highest risk food handling practices at home. Finally, age (P < 0.0001), education level (P = 0.0004), and suffering from gastrointestinal diseases (P = 0.0005) showed significant effects with self-perception of having salmonellosis. PRACTICAL APPLICATION: Data presented in this study could be used in future risk and exposure assessment research to evaluate the public health risk from the consumption of contaminated food. In addition, it could be used by government agencies to design education campaigns in food safety area.