Ipek Goktepe

Biocontrol of Escherichia coli O157: H7 on fresh-cut leafy greens.

The effect of a bacteriophage cocktail (EcoShield™) that is specific against Escherichia coli O157:H7 was evaluated against a nalidixic acid-resistant enterohemorrhagic E. coli O157:H7 RM4407 (EHEC) strain on leafy greens stored under either (1) ambient air or (2) modified atmosphere (MA; 5% O2/35% CO2/60% N2). Pieces (~2 × 2 cm2) of leafy greens (lettuce and spinach) inoculated with 4.5 log CFU/cm2 EHEC were sprayed with EcoShield™ (6.5 log PFU/cm2). Samples were stored at 4 or 10°C for up to 15 d. On spinach, the level of EHEC declined by 2.38 and 2.49 log CFU/cm2 at 4 and 10°C, respectively, 30 min after phage application (p ≤ 0.05). EcoShield™ was also effective in reducing EHEC on the surface of green leaf lettuce stored at 4°C by 2.49 and 3.28 log units in 30 min and 2 h, respectively (p ≤ 0.05). At 4°C under atmospheric air, the phage cocktail significantly (p ≤ 0.05) lowered the EHEC counts in one day by 1.19, 3.21 and 3.25 log CFU/cm2 on spinach, green leaf and romaine lettuce, respectively compared with control (no bacteriophage) treatments. When stored under MA at 4°C, phages reduced (p ≤ 0.05) EHEC populations by 2.18, 3.50 and 3.13 log CFU/cm2, on spinach, green leaf and romaine lettuce. At 10°C, EHEC reductions under atmospheric air storage were 1.99, 3.90 and 3.99 log CFU/cm2 (p ≤ 0.05), while population reductions under MA were 3.08, 3.89 and 4.34 logs on spinach, green leaf and romaine lettuce, respectively, compared with controls (p ≤ 0.05). The results of this study showed that bacteriophages were effective in reducing the levels of E. coli O157:H7 on fresh leafy produce, and that the reduction was further improved when produce was stored under the MA conditions.

The potential of papain and alcalase enzymes and process optimizations to reduce allergenic gliadins in wheat flour

The objectives of this study were to select effective enzymes that catalyze the hydrolysis of allergenic proteins, gliadins, in wheat flour and to optimize the enzymatic treatment conditions. Six proteases were tested. Hydrolyzed samples were tested for residual gliadin concentrations and in vitro allergenicity. The hydrolysis conditions of wheat protein by the effective enzymes were optimized by central composite design. Results showed that alcalase from Bacillus licheniformis, and papain from latex of papaya fruit had greater ability to reduce gliadin content of wheat flour than flavourzyme, pepsin, trypsin or α-chymotrypsin. The sequential-treatment of wheat flour by alcalase-papain was more effective in reducing gliadin content than single enzyme treatment. Under the optimal conditions of sequential enzymatic treatment, gliadin was almost completely removed, resulting in the flour extract showing lowest IgE-binding. Therefore, this could be a promising biotechnology for preparing low allergenic wheat products.

Evaluation of consumers’ perception and willingness to pay for bacteriophage treated fresh produce

Food-borne illnesses caused by bacteria such as enterohemorrhagic E. coli and Salmonella spp. take a significant toll on American consumers’ health; they also cost the United States an estimated

Measurement and modelling of nitrogen dioxide (NO2) emissions: a marker for traffic-related air pollution in Doha, Qatar

77.7 billion annually in health care and other losses.1 One novel modality for improving the safety of foods is application of lytic bacteriophages directly onto foods, in order to reduce or eliminate their contamination with specific foodborne bacterial pathogens. The main objective of this study was to assess consumers’ perception about foods treated with bacteriophages and examine their willingness to pay (WTP) an additional amount (10–30 cents/lb) for bacteriophage-treated fresh produce. The study utilized a survey questionnaire administered by telephone to consumers in 4 different states: Alabama, Georgia, North Carolina, and South Carolina. The results show that consumers are in general willing to pay extra for bacteriophage-treated fresh produce if it improves their food safety. However, income, race, and the state where a consumer lives are significant determinants in their WTP.

Effect of a bacteriophage cocktail in combination with modified atmosphere packaging in controlling Listeria monocytogenes on fresh-cut spinach

In the State of Qatar, recent statistics show a continued increase in the motor-vehicle fleet commensurate with population growth and economic development. This trend, together with the rapid expansion of urban areas and the increased dependence on automobiles, has resulted in an increase in pollution near traffic sources, indicating that the risk of exposure to vehicles’ emissions is higher and that these emissions must be considered in terms of their spatial and temporal occurrence. So far, there are no studies conducted in Qatar to evaluate the traffic-related air pollution. This study is carried out to monitor the levels of nitrogen dioxide (NO2) as a marker of pollution related to traffic. The aim of this study is to build a baseline for traffic-related pollution in Qatar by monitoring and modelling NO2 emissions. The levels of traffic-related air pollution by NO2 were investigated at six major intersections along the C-ring road. The relationship of NO2 was established with traffic volume in each intersection during December 2012 and March–April 2013. Significant differences were established between the pollutant concentrations in each intersection. The CALifornia LINE Source Dispersion Model, version 4 air dispersion model employed had estimated the influence of the measured NO2 concentration on the predicted NO2 values by 31.12%. The low percentage may have accounted for the uncertainties brought by the vehicle emission factor and non-availability of temporal dynamics during the time of sampling. Non-parametric Spearman’s correlation test resulted in a significant correlation between measured and predicted values of NO2 concentrations, rs = 0.525 and p = 0.012.

Enzymatic treatment of peanut butter to reduce the concentration of major peanut allergens

Abstract A Listeria monocytogenes-specific bacteriophage cocktail was evaluated for its activity against a nalidixic acid-resistant L. monocytogenes (Lm-NalR) isolate on fresh-cut spinach stored under modified atmosphere packaging at various temperatures. Pieces (~2 × 2 cm2) of fresh spinach inoculated with 4.5 log CFU/cm2 Lm-NalR were sprayed with the phage cocktail (6.5 log plaque-forming units [PFU]/cm2) or a control. The samples were stored at 4°C or 10°C for up to 14 d in sealed packages filled with either atmospheric air (AA) or modified atmosphere (MA). At 4°C under AA, the phages significantly (P ≤ 0.05) lowered the Lm-NalR populations on spinach, compared to control-treated inoculated samples, by 1.12 and 1.51 log CFU/cm2 after 1 and 14 d, respectively. At 4°C under MA, Lm-NalR was significantly reduced by 1.95 log CFU/cm2 compared to control leaves after both 1 and 14 d. At 10°C under AA, the phages significantly reduced Lm-NalR by 1.50 and 2.51 log CFU/cm2 after 1 and 14 d compared to the control. Again at 10°C under MA, the phages significantly reduced Lm-NalR by 1.71 and 3.24 log CFU/cm2 compared to control after 1 and 14 d, respectively. The results support the potential of lytic bacteriophages in effectively reducing populations of L. monocytogenes on freshcut leafy produce, under both AA and MA conditions.