Campylobacter heat resistance - past, current status and future prospect for New Zealand and beyond

Abstract

New Zealand has a much higher rate of reported campylobacteriosis cases than the rest of the developed world. It has been assumed that New Zealand C. jejuni strains have greater heat tolerance and thus are better able to survive cooking. Therefore there is a need to fully determine the temperature dependence of Campylobacter spp. and to update the current knowledge of kinetic parameters such as D and z values of Campylobacter spp. The significantly higher reported Dvalues for Campylobacter spp. already seen in the Netherlands requires a practical stance in ensuring appropriate evaluation of thermal process lethality of Campylobacter spp. An extensive search of data bases for publications on Campylobacter heat resistance was conducted. The kinetic parameters obtained in New Zealand under isothermal and dynamic conditions in broths or in food matrix are broadly in agreement with previously published international data and do not indicate that New Zealand strains are more heat resistant than other strains. This finding has a significant impact to regulators, consumers, food industry and researchers as it has revealed the scientific evidence to maintain the standards for the heat treatment practices. Any change of heat treatment practice can cause unpredicted loss to the poultry industry and challenges the regulatory bodies to convey the message of altering the consumers cooking temperature to all consumers with a short time given the reluctance of consumers in using thermometers to verify the cooking temperature at home. Consumers play an important role in making certain the food they prepare is safe by preventing cross-contamination in order to avoid the risk of food borne diseases.

Survival of Campylobacter jejuni in chicken at refrigeration and cooking temperatures

“…Campylobacter spp. are fastidious bacteria, sensitive to high and low temperatures (Al-Sakkaf, 2015;Hansson et al, 2018). Therefore, physical interventions, such as chilling or freezing, reduce the contamination of chicken (Sampers et al, 2010;Boysen et al, 2013;Casagrande Proietti et al, 2018) and may result in a lower risk of consumer infection.…”

“…Therefore, physical interventions, such as chilling or freezing, reduce the contamination of chicken (Sampers et al, 2010;Boysen et al, 2013;Casagrande Proietti et al, 2018) and may result in a lower risk of consumer infection. Nevertheless, retail storage conditions for poultry meat often facilitate the Campylobacter survival at lower temperatures (Ritz et al, 2007;Hansson et al, 2018), while safety at the consumer stage relies on domestic kitchen practices, including food hygiene and appropriate cooking (Membré et al, 2013;Al-Sakkaf, 2015;Langsrud et al, 2020).…”

“…Laboratory studies allow to estimate the effect of domestic decontamination procedures for the Campylobacter number on artificially contaminated chicken. However, the mean log reduction of Campylobacter by physical decontamination of chicken is strongly dependent on the tested strains (Boysen et al, 2013;Al-Sakkaf, 2015;Gomes et al, 2018). Studies on C. jejuni survival in laboratory to date have only focused on strains isolated in other countries (Boysen et al, 2013;Al-Sakkaf, 2015), which make it difficult to compare the effect of such strategies on pathogen reduction.…”

“…Interestingly, a metaanalysis has found a log linear effect of temperature within a range of 0 to 42°C on Campylobacter survival, highlighting an ability to persist under 4°C for almost two weeks on a meat matrix (Membré et al, 2013). Although an in vitro analysis have shown the ability of Campylobacter coli Brazilian strains to grow at 4°C for 24 hours in microaerobic conditions, after inoculation in Brain Heart Infusion (BHI) broth (Gomes et al, 2018), it should be noted that thermotolerant Campylobacter are unable to multiply in foods under retail or household storage at low temperatures (Ritz et al, 2007;Membré et al, 2013;Al-Sakkaf, 2015). As found in the present study, the reduced level of C. jejuni during chilled storage of chicken has been reported in comparison with the initial contamination level (Sampers et al, 2010;Casagrande Proietti et al, 2018), but without achieving the pathogen inactivation.…”

“…Based on the resulting equation, the estimated parameters showed 1.35 log reduction of C. jejuni (CFU g -1 ) for each increase of 1 log in the exposure period in minutes at 70°C (Figure 2). The thermal inactivation of Campylobacter depends on the adequate distribution of the temperature in the foodstuff (Al-Sakkaf, 2015;Lahou et al, 2015). Whereas Campylobacter numbers in artificially inoculated chicken burgers have dropped below detectable levels, after 4 min of frying, when core temperature has reached 57.5°C (Sampers et al, 2010), other authors showed that the core temperature of 70°C in hamburgers is not always reached during the regular cooking time, allowing Campylobacter to survive (Lahou et al, 2015).…”