Aims:  To investigate the changes in bacterial diversity on fresh spinach phyllosphere associated with storage at refrigeration temperatures. Methods and Results:  Community structure and population dynamics of spinach phylloepiphytic bacteria associated with packaging and refrigeration of ready‐to‐eat fresh produce were evaluated using pyrosequencing of 16S rRNA gene amplicons. A diverse community responsive to storage at refrigerated temperatures was detected belonging to over 1000 operational taxonomic units, including many diverse members not previously described on the phyllosphere. Of the approx. 8800 unique sequences examined from fresh spinach leaves, 75% were from previously undescribed taxa. The classified sequences from the fresh spinach phyllosphere were assigned to 11 different phyla with the largest number of reads belonging to Proteobacteria and Firmicutes. Packaging and storage of spinach under refrigerated conditions decreased the richness, diversity and evenness of the bacterial community. Refrigeration at 4 and 10°C and storage resulted in a decrease in number of taxa represented from 11 phyla in fresh spinach to only 5 phyla after 1 day of storage. Sequences belonging to γ‐Proteobacteria, particularly Pseudomonas spp. and members of the Enterobacteriaceae, were the most numerous after 15 days of storage at both temperatures. Growth inhibition of the genera Escherichia was achieved at 4°C but not at 10°C storage, thus highlighting the importance of temperature in fresh packaged spinach. Conclusions:  The application of pyrosequencing to describe composition and diversity of the phyllosphere on spinach leaves provided a broader outlook of the bacterial composition of this community complementing other phyllosphere studies that have used culture‐ and nonculture‐dependent approaches. Significance and Impact of the Study:  Pyrosequencing allowed a broader description of the bacterial composition and diversity of the spinach leaf surface than previously obtained using culture‐based detection and will be a powerful tool to help ensure the future safety and quality of packaged spinach.

Curli fibers are produced by some Escherichia coli cells in response to environmental stimuli. These extracellular proteins enhance the cell's ability to form biofilms on various abiotic surfaces. E. coli 0157:H7 cells readily attach to a variety of fruit and vegetable surfaces. It is not known whether the expression of curli influences the cell's ability to attach to produce surfaces. In this study, the effect of curli expression on the cell's overall hydrophobicity, charge, and ability to attach to cut and whole iceberg lettuce surfaces was examined. All strains, regardless of curli expression, attached preferentially to the cut edges of lettuce (P< 0.05). The curli-producing cells of E. coli 0157:H7 strain E0018 attached in significantly greater numbers to both cut and whole lettuce pieces than did the non-curli-producing E0018 cells (P < 0.05); however, no significant attachment differences were observed between the curli-producing and non-curli-producing cells of E. coli 0157:H7 strains 43894 and 43895. All curli-producing E. coli 0157:H7 strains were significantly more hydrophobic (P < 0.01); however, no association between the cells' hydrophobic characteristics and lettuce attachment was observed. Overall surface charge of the cells did not differ among strains or curli phenotypes. Results indicate that overall hydrophobicity and cell charge in E. coli 0157:H7 strains do not influence attachment to iceberg lettuce surfaces. The presence of curli may not have any influence on attachment of E. coli 0157:H7 cells to produce items. Additional factorsmay influence the attachment of E. coli 0157:H7 to plant surfaces and should be further examined.

As produce consumption has increased, so have foodborne disease outbreaks associated with fresh produce. Little research has addressed food safety practices used on small to medium-sized farms selling locally or in farmers markets. This study evaluated current food safety practices used by farmers on small to medium-sized farms and managers of farmers markets in Georgia, Virginia, and South Carolina based on responses to surveys. Surveys were developed, pretested, and revised before implementation with target audiences and were implemented via mail and the Web to maximize participation, with reminders sent to nonrespondents. Data were collected from 226 farmers and 45 market managers. Frequencies and percentages were calculated for all response variables. Responses from farmers indicated that more than 56% of them use manures. Of those who use manures, 34% use raw or mixtures of raw and composted manure, and over 26% wait fewer than 90 days between application of raw manure and harvest. Over 27% use water sources that have not been tested for safety for irrigation, and 16% use such water sources for washing produce. Over 43% do not sanitize surfaces that touch produce at the farm. Only 33% of farmers always clean transport containers between uses. Responses from market managers indicated that over 42% have no food safety standards in place for the market. Only 2 to 11% ask farmers specific questions about conditions on the farm that could affect product safety. Less than 25% of managers sanitize market surfaces. Only 11% always clean market containers between uses. Over 75% of markets offer no sanitation training to workers or vendors. While farmers and market managers are using many good practices, the results indicate that some practices being used may put consumers at risk of foodborne illness. Consequently, there is a need for training for both farmers and market managers.

Tomatoes have been linked to outbreaks of salmonellosis, demonstrating the need to identify sources of contamination. Objectives of this study included determining the ability for Salmonella enterica serovar Montevideo to be internalized into tomatoes from contaminated irrigation water and seed stock, and establishing whether Salmonella Montevideo can survive in fertilizer solutions. Six treatment groups (five plants per group) were irrigated with 350 ml of 7 log CFU/ml of Salmonella Montevideo every 14 days for 70 days, each group receiving an increased number of contaminated water events progressively: group 1 received one contaminated watering at day 0, and group 6 received a total of six contaminated waterings. Group 7 was a control, and group 8 was grown from seeds soaked in 8 log CFU/ml of Salmonella Montevideo for 24 h. All plants were watered daily with uncontaminated water. Three replications were completed. Fruit from every plant, and roots, stems, and leaves of one plant per treatment were sampled. All tomatoes were negative for Salmonella Montevideo; five root samples tested positive. For fertilizer studies, a commercially available fertilizer, two custom mixed and 1.0% dilutions of each (total of six solutions), and sterile water were inoculated with 8 log CFU/ml of Salmonella Montevideo and stored at 25 degrees C. Solutions were sampled at 24, 48, and 72 h. There were no differences (P > or = 0.05) between survival of Salmonella Montevideo in diluted fertilizers and the control. Results indicate Salmonella Montevideo is unable to contaminate tomato fruit via irrigation water and seed stock but can survive in fertilizer solutions.

No abstract

Sodium benzoate has been shown to produce benzene in combination with ascorbic acid. This has led to research for safe alternatives from plant essential oils and parabens that have shown some antimicrobial activity, but many of these compounds exhibit poor solubility in aqueous solutions. Cyclodextrins can increase the solubility of many compounds. This work aimed to investigate the solubility of 23 plant essential oils and 4 parabens in water and an apple juice medium. Four of these compounds were chosen for their low aqueous solubility to determine if complexing the compound with α- and β-cyclodextrin would increase solubility. Three of the complexes were dissolved in an acidified aqueous solution and then studied in glass and polyethylene terephthalate (PET) to determine if storage material would affect the stability. Solubility of the 27 compounds in distilled water ranged from 1.6 mg/L to 2460.6 mg/L and the solubility of 18 of the compounds decreased from 2.5 to 84.7% in apple juice medium (pH = 3.4, 12-13 °Brix). Complexation with cyclodextrin dramatically increased the solubility of the compounds, up to 10-fold. Packaging material had no effect on concentration of compounds present over 7 days. Cyclodextrins were able to increase solubility of these compounds to more suitable concentrations, and may lead to viable natural alternatives to sodium benzoate.

No abstract

Chili peppers (Capsicum spp.) may possess antibacterial properties and have potential to be used in foods as antimicrobial. The complete chili pepper extract should be evaluated to determine which compounds are responsible for the antimicrobial activity. Extraction of compounds from the pepper is completed using a solvent. The type of solvent used for extraction influences which compounds are isolated, therefore the best extraction method needs to be determined. The purpose of this study was to identify which solvent is most successful at extracting unknown antibacterial compounds from jalapeño peppers. Fresh jalapeño peppers were chopped, weighed, and blended with a solvent (sterilized hot water, 70% methanol, 95% methanol, 70% ethanol, or 95% ethanol) at a 1:1 ratio (g/g) until the mixture was homogenized, followed by shaking for 15 min. The slurry was centrifuged; supernatant was removed and used for antibacterial testing against Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica. The diameter of growth inhibition was measured and statistically evaluated using ANOVA to determine the extract with the greatest antimicrobial activity. Solvents were tested alone as a control. There was greater bacterial inhibition from extracts created with methanol and ethanol than hot water. Listeria monocytogenes was significantly more susceptible to the extracts than E. coli or Salmonella isolates. Each solvent extract was then analyzed using high‐performance liquid chromatography (HPLC) and fractions (A–G) were collected and used for subsequent disk diffusion analysis against L. monocytogenes. Fractions E and F (eluded between 20 and 30 min) exhibited the most antibacterial activity. There were no differences between solvents used (p = .05). Further investigation into specific compounds within these extracts will be completed in the future.