The risk of Listeria from non-prepacked, ready-to-eat cooked meat sold at retail has been evaluated in Greece.

The work assessed Listeria monocytogenes exposure related to consumption of non-prepackaged ready-to-eat (RTE) cooked meat products handled at retail environments in the country.

The European Food Safety Authority (EFSA) awarded a grant to the Hellenic Food Authority (EFET) and Aristotle University of Thessaloniki for the work. While deli meats represent a risk for listeriosis among RTE foods, most available data are related to pre-packaged food products.

Nitrate impact and Listeria prevention
The evaluation found probability of illness per serving was highly related to nitrite concentration with items that had lower levels showing a higher risk per serving. Initial prevalence and concentration of Listeria immediately after slicing and storage temperature and time in the domestic refrigerator had the highest impact on probability of illness.

Modeling predicted seven listeriosis cases per year but setting a use-by date of 14 days and improving temperature of domestic storage eliminated these annual cases. Results showed most listeriosis cases are related to longer storage of the products and higher temperatures of domestic refrigerators.

Data on consumption of non‐prepacked RTE cooked meat products, types of these products on the Greek market including analyzes of water activity, pH, concentration of nitrite and lactic acid bacteria, consumer practices after purchase of the products such as transport time, handling, storage, temperature profiles in household refrigerators and Listeria monocytogenes prevalence of the slicing machine and sliced RTE product were collected.

The nine non-prepacked RTE cooked meats Greek households reported to buy and eat are parizer, mortadella, boiled and smoked turkey, boiled and smoked ham, smoked steak and boiled and smoked chicken. The most cases was predicted for mortadella, smoked turkey, boiled turkey and parizer, which were the top frequently consumed categories.

A quantitative microbial risk assessment (QMRA) model was developed based on the prevalence and concentration at retail level, growth during domestic storage and consumption data. It predicted listeriosis risk related to consumption of meat products handled at retail stores in Greece.

Slicing machine sampling
Samples were taken at retail points in the region of Attica, Greece. Two of 300 slicing machines for cooked meat products were Listeria monocytogenes-positive.

In one of those, Listeria was also detected on meat previously sliced; but at a concentration below the limit of quantification. So, the estimated prevalence of Listeria on the sliced non-prepackaged RTE cooked meat products was 0.33 percent.

Sampling was performed between 10am and 12.30 Monday to Wednesday from January to March 2018 so samples were not taken first thing in the morning when equipment was still clean.

In total, 87 non-prepackaged RTE cooked meat items sliced at retail were analyzed for pH, water activity, nitrite concentration and lactic acid bacteria. The pH ranged from 5.63 to 7.18 with a mean of 6.34. Water activity went from 0.965 to 0.993 with a mean of 0.979. Lactic acid bacteria concentration ranged from 2.55 to 6.8 log CFU/g with a mean of 4.74 and nitrite concentration from 0.16 to 207.6 ppm with a mean of 26.6.

Three RTE meat products — boiled turkey, boiled ham and smoked turkey — from different producers were seleced representing a high, medium and low concentration of nitrite. The validation experiment was done at three static and two dynamic temperatures simulating conditions during domestic storage.

The QMRA model ranked the 87 tested products based on probability of illness per serving. Those with lower nitrite concentration showed a greater risk per serving and ranked higher.

Differences in probability of illness per serving among products tested were very small, indicating the type of product is not a significant risk factor in the probability of illness per serving. Initial prevalence and concentration of Listeria immediately after slicing and storage temperature and time in the domestic refrigerator had the highest impact on the probability of illness.

The QMRA model predicted a median number of seven listeriosis cases per year for the population.

Setting a use-by date of 14 days in non-prepackaged RTE cooked meat products and improving temperature of domestic storage eliminated the median number of annual cases. Currently, a use-by date for such products sliced at retail is not required.

Consumer role
The Hellenic Center for Disease Control and Prevention (HCDCP) reported 158 cases of listeriosis were recorded in Greece from 2004 to 2017 through the mandatory notification system and 33 people died.

A questionnaire-based consumer survey was conducted via telephone with 800 households across Greece to collect data on consumption of non-prepackaged RTE meat products and consumers’ food safety knowledge as well as domestic storage and food handling practices in February and March 2018.

Usual time between purchase and putting in the refrigerator is less than 30 minutes for most households. The usual number of days to keep meat slices in the fridge is between four to seven days but some households keep the products for more than 10 days.

Of households that reported food poisoning in the past, most attributed it to food prepared outside the home. only 17 associated food poisoning with RTE meat product consumption. Half of the participants had heard of Listeria but not many could identify foods that could support the growth of this pathogen and increase the risk of listeriosis.

Almost half of participating households did not have a thermometer in their refrigerator and 5 percent said the temperature of the refrigerator was above 16 degrees Celsius.

Before handling RTE meat products almost nine in 10 interviewees washed or rinsed their hands with soap or water.

A European workshop to discuss the findings was organized in February this year. In total 80 people attended from Austria, Belgium, Bulgaria, Croatia, Czech Republic, Cyprus, Finland, France, Germany, Ireland, Italy, Latvia, Norway, Poland, Spain, Sweden, and the Netherlands.

It also covered risk assessment to risk management, epidemiology, human pathogenesis and other countries activities on Listeria monocytogenes.