Significance and Impact of the Study: Freezing chicken livers can reduce, but not eliminate, campylobacters. If poultry processors were to freeze livers destined for human consumption as part of routine processing, there is a potential for a reduction in campylobacteriosis associated with the consumption of imperfectly cooked chicken livers and derivatives, such as pât e. AbstractThe aims of this study were (i) to determine the prevalence and numbers of campylobacters in 63 samples of raw livers purchased at retail across the UK and (ii) to investigate whether the freezing of chicken livers contaminated with Campylobacter was a reliable method for decontamination. Chicken livers naturally contaminated with campylobacters were subjected to freezing at À15 and À25°C for one day and 7 days. Numbers of campylobacters on the livers were determined immediately before and after a 24-h or 7-days freeze treatment and daily during 3 days post-thaw refrigerated storage. Freezing for 24 h at À25°C can reduce numbers of Campylobacter by up to 2 log 10 CFU g À1 . Freezing the livers for 24 h at À25°C, thawing overnight in a fridge set to 4°C and refreezing for another 24 h at À25°C reduced the numbers of campylobacters by up to three logs. Reduction in the numbers of campylobacters was significantly greater following a second freeze treatment compared with a single freeze treatment.

This study devised a protocol for the manufacture of commercial quantities of chicken liver pâté that reliably destroyed campylobacters. A literature search identified 40 pâté manufacture recipes. Recipes stages with a potential to be antimicrobial were assembled to form a new protocol that included washing with organic acid, freeze-thaw and flambé in alcohol. Naturally-contaminated, high-risk livers were obtained from clearance flocks at slaughter and the effect of each stage of the protocol on Campylobacter populations was determined. Organic acid washing changed the color of the liver surfaces. However, there were no significant differences between liver surface color changes when a range of concentrations of lactic acid and ethanoic acid washes were compared by reflective spectrophotometry. A 5% (w/v) acid wash reduced numbers of indigenous campylobacters by around 1.5 log10 CFU/g for both acids. The use of a Bain Marie was found to more reproducibly apply heat compared with pan-frying. Antimicrobial recipe stages reduced the numbers of campylobacters, but not significantly if thermal processing was ineffective. Cooking to 63°C was confirmed to be a critical control point for campylobacters cooked in a Bain Marie. Organoleptic and sensory assessment of pâté determined an overall preference for pâté made from frozen livers.

Summary Four trials were carried out at a broiler processing plant to examine the effectiveness of spraying lactic acid solutions for reducing the numbers of Campylobacter on carcasses. The carcasses were naturally contaminated and treated after the inside–outside washer and before the air chiller. Carcasses were treated by spraying in a tunnel or with one of two hand‐held sprayers. Carcasses were treated with a 1.9%, 4% or 8% solution of lactic acid buffered to pH 4 using sodium lactate, and testing was carried out on skin samples from the breast or back/neck. Treating carcasses with 1.9% acid was not effective. Treatments with 4% acid reduced the numbers of Campylobacter on breast skin by 0.4 log10 cfu g−1 or less and on back/neck skin by 0.8 log10 cfu g−1. Spraying with an 8% acid solution in the tunnel produced a 1.9‐log cfu g−1 reduction on breast skin but adversely affected the appearance of the carcasses. Further work is suggested with a 5% solution with consumer testing for acceptability of appearance.

To investigate whether the efficacy of live vaccines is influenced by the mode of vaccine delivery, a widely-used UK live commercial Salmonella Enteritidis vaccine was delivered to pullet chicks either by spray, in drinking water, or in combination with a bivalent vaccine containing inactivated Salmonella Enteritidis and Salmonella Typhimurium. The birds were subsequently challenged with 10(2) or 10(8) colony-forming units (cfu) of Salmonella Enteritidis through drinking water at either six or 20 weeks of age. Ten days after the challenge, the birds were euthanased and their caecal contents cultured for Salmonella. All of the vaccinated groups contained fewer Salmonella Enteritidis-positive birds than the unvaccinated groups. The 'spray-vaccinated' group contained significantly fewer Salmonella Enteritidis-positive birds than the 'water-vaccinated' group after challenge with 10(8) cfu at 20 weeks. However, there was little or no difference at the other challenge time points between the groups that received vaccine through different modes of delivery.

Aims: To determine the fate of Escherichia coli on vegetables that were processed through commercial wash treatments and stored under simulated retail conditions at 4°C or wholesale at fluctuating ambient temperatures (0-25°C, dependent on season). Methods and Results: Bovine slurry that was naturally contaminated with E. coli O145 was applied without dilution or diluted 1:10 using borehole water to growing potatoes, leeks or carrots. Manure was applied 1 week prior to harvest to simulate a near-harvest contamination event by manure deposition or an application of contaminated water to simulate a flooding event or irrigation from a contaminated water source. At harvest, crops were contaminated at up to 2 log cfu g À1 . Washing transferred E. coli into the water of a flotation tank used for potato washing and did not completely remove all traces of contamination from the crop. Manure-contaminated potatoes were observed to contain 0Á72 cfu E. coli O145 g À1 after processing and retail storage. Manure-contaminated leeks harboured 0Á73-1Á55 cfu E. coli O145 g À1 after washing and storage. There was no cross-contamination when leeks were spray washed. Washing in an abrasive drum resulted in less than perfect decontamination for manure-contaminated carrots. There were five postdistribution isolations from carrots irrigated with contaminated water 24 h prior to harvest. Conclusions: Standard commercial washing and distribution conditions may be insufficient to reliably control human pathogenic E. coli on fresh produce. Significance and Impact: Previous speculation that the cause of a UK foodborne disease outbreak was soil from imperfectly cleaned vegetables is plausible. IntroductionConsumption of fresh fruit and vegetables is associated with good nutrition in humans because they provide an important source of vitamins, minerals and biochemical cofactors (Augusto et al. 2015). However, in recent years, there have been a number of high-profile foodborne illness outbreaks that have been traced back to fresh produce (King et al. 2012;Laidler et al. 2013). In the United Kingdom in 2011, an outbreak of 250 infections was caused by verocytotoxigenic E. coli (VTEC) O157 phage type (PT) 8 (Launders et al. 2015). The consequent casecontrol-based investigation concluded that there was a significant correlation between infection and those households where there was domestic preparation of unwrapped leeks, or potatoes bought in paper sacks. Since both leeks and potatoes are cooked before consumption, a hypothesis was proposed that cross-1597