Search

In May 2016, labeling of certain nonintact mechanically tenderized beef (MTB) products was mandated in the United States. MTB products should be handled differently by the consumer because pathogens can be transferred from the exterior to the interior of the meat during the tenderization process. Without labeling, it is difficult to visually distinguish between some intact beef and MTB products, which is a concern because MTB products require higher internal cooking temperatures for safety. An exploratory study was conducted to understand consumer understanding of MTB products and consumer responses to the new label. Thirteen focus groups were convened in rural and urban settings across Virginia and North Carolina between December 2015 and May 2016. Sessions were audiorecorded, transcribed verbatim, and analyzed through constant-comparison thematic analysis. Although MTB products were commonly bought, prepared, and consumed, consumer awareness of MTB products and the MTB process was limited. Generally, the label confused participants, and they did not understand the message. Specifically, terminology such as "blade tenderized" and "mechanically tenderized" were preferred over the term "needle tenderized" on labels. Once explained, many individuals wanted more information and better messaging. Through a multiprong approach, other messaging methods (e.g., in stores, through technology, and with certifications) were highly valued by consumers and may result in increased message clarity. Ultimately, the intrinsic and extrinsic properties of the beef rather than the MTB product continued to be the primary guide for purchasing and preparation. This study is the first to be conducted regarding American perceptions of MTB products. An understanding of consumer awareness of MTB products and labels is needed to develop targeted risk messaging communication tools.

Salmonellosis has been increasingly associated with contaminated spices. Identifying inoculation and stabilization methods for Salmonella on whole spices is important for development of validated inactivation processes. The objective of this study was to examine the effects of inoculation preparation on the recoverability of Salmonella enterica from dried whole peppercorns and cumin seeds. Whole black peppercorns and cumin seeds were inoculated with S. enterica using one dry transfer method and various wet inoculation methods: immersion of spice seeds in tryptic soy broth (TSB) plus Salmonella for 24 h (likely leading to inclusion of Salmonella in native microbiota biofilms formed around the seeds), application of cells grown in TSB, and/or application of cells scraped from tryptic soy agar (TSA). Postinoculation seeds were dried to a water activity of 0.3 within 24 h and held for 28 days. Seeds were sampled after drying (time 0) and periodically during the 28 days of storage. Salmonella cells were enumerated by serial dilution and plated onto xylose lysine Tergitol (XLT4) agar and TSA. Recovery of Salmonella was high after 28 days of storage but was dependent on inoculation method, with 4.05 to 6.22 and 3.75 to 8.38 log CFU/g recovered from peppercorns and cumin seeds, respectively, on XLT4 agar. The changes in surviving Salmonella (log CFU per gram) from initial inoculation levels after 28 days were significantly smaller for the biofilm inclusion method (+0.142pepper, +0.186cumin) than for the other inoculation methods (-0.425pepper, -2.029cumin for cells grown on TSA; -0.641pepper, -0.718cumin for dry transfer; -1.998pepper for cells grown in TSB). In most cases, trends for reductions of total aerobic bacteria were similar to those of Salmonella. The inoculation method influenced the recoverability of Salmonella from whole peppercorns and cumin seeds after drying. The most stable inoculum strategies were dry transfer, 24-h incubation of Salmonella and spices in TSB (i.e., potential inclusion of Salmonella within native microbiota biofilms), and inoculation of Salmonella cells grown on TSA subsequent to drying. However, with the dry transfer method it was difficult to obtain the large amount of inoculum needed for inactivation studies.

Fresh and fresh-cut tomatoes have been associated with numerous outbreaks of salmonellosis in recent years. One effective post harvest treatment to reduce Salmonella enterica in tomatoes may be high pressure processing (HPP). The objectives of the study were to determine the potential for HPP to reduce S. enterica serovars Newport, Javiana, Braenderup and Anatum in tryptic soy broth (TSB) and to determine the effect of HPP to reduce the most pressure resistant of the four serovars from fresh diced and whole tomatoes. To evaluate pressure resistance, TSB containing 8 log CFU/ml of one of the four serovars was packaged in sterile stomacher bags and subjected to one of three different pressures (350, 450 or 550MPa) for 120s. The most pressure resistant S. enterica serovar evaluated was Braenderup. Subjecting the broth culture to 350, 450 and 550MPa resulted in a 4.53, 5.74 and 7.09 log reduction in S. Braenderup, respectively. Diced tomatoes (150g) and whole red round tomatoes (approximately 150g) were inoculated with 0.1ml of 9.1 log CFU/ml S. Braenderup, and subjected to the same pressure treatments (350, 450 or 550MPa). Significant reductions of S. Braenderup concentrations in diced tomatoes (P<0.05) were seen after processing at 350 (0.46CFU/g), 450 (1.44 log CFU/g), and 550MPa (3.67 log CFU/g). In whole tomatoes, significant reductions (P<0.05) were also seen at 350 (1.41 log CFU/g), 450 (2.25 log CFU/g) and 550MPa (3.35 log CFU/g). HPP may be an effective post harvest strategy to reduce low levels of S. enterica contamination in whole and diced tomatoes., (Published by Elsevier B.V.)

Environmental factors encountered during growing and harvesting may contribute to Escherichia coli O157:H7 contamination of lettuce. Limited nutrients and extended exposure to water may cause E. coli O157:H7 to shed its O antigen. Absence of the O157-polysaccharide antigen could affect the cell's physicochemical properties (hydrophobicity and cell charge) and ultimately influence its attachment to surfaces. The objectives of this study were to evaluate the effect of the E. coli O157:H7 O-antigen on the cell's overall hydrophobicity, charge and ability to attach to cut edge and whole leaf iceberg lettuce surfaces. Three strains of E. coli O157:H7 (86-24 wild type; F-12, mutant lacking the O-antigen and pRFBE, plasmid for O157 gene reintroduced) were examined for their hydrophobicity, overall charge and ability to attach to lettuce. Overall, E. coli O157:H7 attached at higher levels to cut surfaces over whole leaf surfaces (P=0.008) for all strains and treatments. Additionally, the strain lacking the O-antigen (F12)-attached significantly less to lettuce (P=0.015) than the strains expressing the antigen (WT and pRFBE). Cells lacking the O antigen (strain F-12) were also significantly more hydrophobic than strains 86-24 or pRFBE (P≤0.05). Surface charge differed among the strains tested (P≤0.05); however, it did not appear to influence bacterial attachment to lettuce surfaces. The charge was not fully restored in the pRFBE strain (expression of O-antigen reintroduced), therefore, no conclusions can be made pertaining to the effect of charge on attachment in this study. Results indicate that E. coli O157:H7 cells which lack the O-antigen have greater hydrophobicity and attach at lower concentrations than cells expressing the O-antigen, to iceberg lettuce surfaces., (Published by Elsevier B.V.)

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.

Inactivation of Escherichia coli O157:H7 suspended in salt solutions (Na(2)PO(4), NaCl, NaNO(3), NH(4)Cl, CaCl(2), and AlCl(3)) at concentrations ranging from 0 to 5% (w/v) by high-intensity ultrasound at two different temperature conditions (ice water bath, 40 degrees C water bath) and three ultrasonic intensity levels (9.5, 21.8, 49.2 W/cm(2)) was determined. Increases in sonication treatment time, intensity, and temperature led to increased lethality of E. coli O157:H7. However, cell lethality, as a function of solute concentration, varied depending upon type of salt. CaCl(2), NaCl, NaNO(3), Na(2)PO(4), and NH(4)Cl had little or no effect on survival of E. coli O157:H7 (<1-log reduction) regardless of other treatment conditions at 9.5 W/cm(2). Concentrations of >0.5% of CaCl(2), NaNO(3), Na(2)PO(4), and NH(4)Cl adversely affected survival (1.0- to 1.6-log reduction) with treatment of 21.8 W/cm(2) in an ice bath and showed greater inactivation (1.2-4.0-log reduction) in the 40 degrees C water bath. Treatment of 49.2 W/cm(2) showed the greatest impact regardless of other parameters. In the 40 degrees C water bath, treatment for 10 min at 49.22 W/cm(2) led to total inactivation for cells suspended in 0.5% NH(4)Cl, 1% CaCl(2), 2% NaCl, 5% Na(2)PO(4), and all concentrations of AlCl(3). Complete inactivation also occurred in an ice bath for 5% AlCl(3), which was shown to be the most effective salt. The most efficient treatment combination was in the 40 degrees C water bath for 10 min at 49.2 W/cm(2) with 5% AlCl(3). Inactivation of E. coli O157:H7 is attributed to cavitation-induced shear forces, reaction of cavitation-generated hydrogen peroxide with microbial cell wall constituents and electrostatic interactions of dissociated salts with cell membranes.

Inactivation of Escherichia coli O157:H7 and Salmonella in apple cider and orange juice treated with ozone was evaluated. A five-strain mixture of E. coli O157:H7 or a five-serovar mixture of Salmonella was inoculated (7 log CFU/ml) into apple cider and orange juice. Ozone (0.9 g/h) was pumped into juices maintained at 4 degrees C, ambient temperature (approximately 20 degrees C), and 50 degrees C for up to 240 min, depending on organism, juice, and treatment temperature. Samples were withdrawn, diluted in 0.1% peptone water, and surface plated onto recovery media. Recovery of E. coli O157:H7 was compared on tryptic soy agar (TSA), sorbitol MacConkey agar, hemorrhagic coli agar, and modified eosin methylene blue agar; recovery of Salmonella was compared on TSA, bismuth sulfite agar, and xylose lysine tergitol 4 (XLT4) agar. After treatment at 50 degrees C, E. coli O157:H7 populations were undetectable (limit of 1.0 log CFU/ml; a minimum 6.0-log CFU/ml reduction) after 45 min in apple cider and 75 min in orange juice. At 50 degrees C, Salmonella was reduced by 4.8 log CFU/ml (apple cider) and was undetectable in orange juice after 15 min. E. coli O157:H7 at 4 degrees C was reduced by 4.8 log CFU/ml in apple cider and by 5.4 log CFU/ml in orange juice. Salmonella was reduced by 4.5 log CFU/ml (apple cider) and 4.2 log CFU/ml (orange juice) at 4 degrees C. Treatment at ambient temperature resulted in population reductions of less than 5.0 log CFU/ml. Recovery of E. coli O157:H7 and Salmonella on selective media was substantially lower than recovery on TSA, indicating development of sublethal injury. Ozone treatment of apple cider and orange juice at 4 degrees C or in combination with mild heating (50 degrees C) may provide an alternative to thermal pasteurization for reduction of E. coli O157:H7 and Salmonella in apple cider and orange juice.

The efficacy of ozone and ultraviolet light (UV) treatment as hurdles against Listeria monocytogenes suspended in fresh (9% NaCl, 91.86% transmittance) and spent brines (20.5% NaCl, 0.01% transmittance) was evaluated. Brines were inoculated with a cocktail of L. monocytogenes -strains N1-227, N3-031, and R2-499. Ozonation was performed by sparging gaseous ozone into brine. This was followed by UV irradiation (253.7 nm) of the brine in sterile quartz cuvettes. Enumeration was performed by spread plating on modified Oxford medium and Trypticase Soy agar supplemented with yeast extract. In fresh brines containing L. monocytogenes , 10 min of ozonation lead to a 7.44 ± 0.13 log CFU/ml mean reduction and 10 min of UV radiation caused a 1.95 ± 0.41 log CFU/ml mean reduction. Sequential exposure of 10 min of ozonation and UV resulted in >9 log CFU/ml reduction in L. monocytogenes populations in fresh brine. Sixty minutes of ozonation of spent brines resulted in a 4.85 ± 0.61 log CFU/ml mean reduction of L. monocytogenes populations. Ten minutes of UV exposure in spent brines resulted in 0.49 ± 0.14 log CFU/ml mean reduction in L. monocytogenes . A sequential treatment of 60 min ozonation and 10 min UV resulted in an excess of 5 log CFU/ml reduction in L. monocytogenes cells in spent brine. Ozonation did not cause a significant increase in the transmittance of the spent brine to aid UV penetration but resulted in color change. Sequential treatments of Ozonation and UV maybe effective in reducing L. monocytogenes in chill brines. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated the effects of packaging and storage temperature on the spinach phylloepiphytic bacterial community and fate of Escherichia coli O157:H7. Freshly harvested spinach was rinsed and/or disinfected, packaged and stored under typical retail conditions (4 °C) or under temperature abuse conditions (10 °C) for a period of 15 days. The final population size of culturable epiphytic bacteria after 15 days of storage was not affected by the temperature of storage or the presence of E. coli O157:H7. However, analysis of the bacterial community using denaturing gradient gel electrophoresis of 16s rDNA revealed changes with time of storage and the presence of E. coli O157:H7. Excision and sequencing of prominent DGGE bands identified that the majority of sequences belonged to the phyla Actinobacteria, Bacteroidetes, Firmicutes and Alphaprotebacteria. After 10 days of storage at 4 °C or 10 °C the population became more dominated by psychrotrophic bacteria. Removal of the epiphytic bacteria resulted in significant increases in numbers of E coli O157:H7 at 10 °C and was associated with decreased expression of E. coli O157:H7 virulence (stxA, curli, eaeA) and stress response (rpoS, sodB) genes. In conclusion, storage temperature and time of storage of packaged spinach affected the diversity of the epiphytic spinach microbiota which influenced the growth, establishment, physiology and potentially virulence of E. coli O157:H7. [Copyright &y& Elsevier]