Tools to fulfil the compliance with the criteria regarding Listeria monocytogenes. Annie Beaufort EU-RL for Listeria monocytogenes

Transcription

1 Tools to fulfil the compliance with the criteria regarding Listeria monocytogenes Annie Beaufort EU-RL for Listeria monocytogenes Product Shelf-Life and Microbilogical Criteria - 17 th November 2011

2 The safety of foodstuffs is ensured by a preventive approach including: - GHP (Good Hygiene Practices) - HACCP system (Hazard Analysis Critical Control Point) All factors having an impact on microbiological quality must be taken into account: - the quality of raw materials - the good hygiene practices - the evolution of identified hazards during the product s shelf life. Microbiological analyses are used as a verification of the whole process.

3 Shelf-life studies must be conducted for any foodstuffs to investigate compliance with the criteria. In particular, for RTE foods able to support the growth of Listeria monocytogenes.

4 L. monocytogenes (Gram-positive, non-spore forming bacteria) is psychrotrophic. L. m can develop in difficult conditions. According to scientific data: temperature: -2 C ph: 4.2 a w : 0.93 L. m has considerable surface adhesion abilities. L. m can be found in many foods. It can cause listeriosis.

5 Transmitted to humans by foods. Incubation: from 2 days to 3 months (on average: 1 month). Listeriosis can cause: bacteraemia, septicaemia infections of the central nervous system maternal-foetal infections that can lead to: miscarriage premature birth infection in the newborn infant. It can cause gastroenteritis, although this is rare. Lethality is high: around 20%. Asymptomatic carriage is estimated to be between 1 and 20%.

6 Listeriosis probability has been modelised Listeriosis probability Ex: Listeriosis probability according to the susceptibility Susceptible persons Healthy persons Dose (Log cfu/g)

7 EC Regulation specifies : Shelf-life studies must be conducted for any foodstuffs to investigate compliance with the criteria. In particular, for RTE foods able to support the growth of Listeria monocytogenes.

8 A RTE food means a food that is consumed without cooking (or other processing effective in the reduction or elimination of the bacteria) by the consumer; it represents a large range including: Cheeses, butter, margarines Fruits and vegetables Biscuits, chocolate Delicatessen Pastries, bread

9 with ph 4.4 or a w 0.92 with ph 5 and a w 0.94 In practice, such RTE foods may support the growth of L. m. with a shelf-life less than 5 days frozen RTE foods In these cases, be sure that the limit of 100 cfu/g won t be exceeded. other RTE foods based on scientific justifications.

10 RTE foods of highest concern are those: that may be still contaminated by L. m at the end of the process or can be recontaminated that may support the growth of L. m. Roughly, we can estimate that L. monocytogenes can grow in RTEfoods such as: *soft and semi-soft cheeses *processed meat *seafoods *deli-type salads *sandwiches But, often, the classification of a food in the category of RTE foods that support or don t support the growth of L. monocytogenes results in a case-by-case study.

11 Limits defined for Ready-To-Eat foods (EC regulation No 2073/2005) Food category Sampling plan Limits Stage where the criterion m = M applies For RTE foods able to n support cthe growth of L.m, the limit is: 1.1 RTE foods intended for infants and RTE foods for special medical purposes 1.2 RTE foods able to support the growth of L. monocytogenes 1.3 RTE foods unable to support the growth of L. monocytogenes - absence in 25g at the plant -100 cfu/g on the market if the manufacturer is able to demonstrate that the limit will not be exceed throughout the shelf-life Abs. in 25 g Products placed on the market during their shelf-life cfu/g Products placed on the market during their shelf-life 5 0 Abs. in 25 g Before the food has left the immediate control of the food business operator who has produced cfu/g Products placed on the market during their shelf-life

12 Guidance document on L. monocytogenes shelf-life studies for RTE foods, provided by DG SANCO Technical guidance document on shelf-life studies for L. monocytogenes in RTE foods, provided by the CRL for Listeria monocytogenes

13 First Characteristics step to fulfil ofthe compliance product: physical-chemical with the criteria: characteristics, to collect information preservatives content, type of packaging, related to process, the characteristics foreseen shelf-life. of the food Available scientific literature and research data regarding the growth and survival characteristics of the micro-organisms of concern. Predictive microbiology Durability studies Challenge tests. And, when necessary,

14 The characteristics of a food includes: Ingredients Process Shelf-life ph Each of these factors has an impact on the growth of L. m. a w or salt content Preservatives content Associated microflora Packaging atmosphere

15 Log cfu/g The growth of L. m is influenced by the initial ph of the food Evolution de L. m in jelly at 8 C, according to ph ) ph = 5.5 ph = Days

16 log cfu/g The growth of L. m is influenced by preservatives Evolution of L. m in jelly at 8 C, according to potassium lactate [lactate] = 0 g/l [lactate] = 7 g/l Days

17 log cfu/g The growth of L. m is influenced by associated microflora Evolution of L. m in raw diced bacon at 8 C, according to associated microflora without associated microflora with associated microflora Days

18 Characteristics of the product: physico-chemical characteristics, preservatives content, type of packaging, process, foreseen shelf-life. Second Available step to scientific fulfil the literature compliance andwith research the criteria: data regarding to collect the information growth and survival characteristics from scientific of the micro-organisms literature and of research concern. data. Predictive microbiology Durability studies Challenge tests. And, when necessary,

19 Les caractéristiques du produits Results of scientific researches Evolution of L. m in an identical food. Evolution of L. m in a food presenting close similarities with the studied RTE. Growth limits of L. m according to other factors than ph and a w.

20 Characteristics of the product: physico-chemical characteristics, preservatives content, type of packaging, process, foreseen shelf-life. Available scientific literature and research data regarding the growth and survival characteristics of the micro-organisms of concern. Durability studies Challenge tests. And, when necessary, Predictive When microbiology necessary: to collect data from predictive microbiology.

21 Main predictive microbiology software 21

22 Use of Sym Previus growth interface module 22

23 Use of the Sym Previus growth interface module Gives growth probability of a bacteria in a food : - 2 factors, - at a selected temperature.

24 How to use the Sym Previus growth interface module?

25 Use the Sym Previus growth interface module

26 Use the Sym Previus growth interface module

27 Use the Sym Previus growth interface module Growth probability at 8 C Growth probability at 12 C

28 Use of Sym Previus growth probalistic module 28

29 Use of the Sym Previus probabilistic module Gives growth simulation of a bacteria in a food taking into account variabilities related to : - strains, - food, - initial contaminations. 29

30 How to use the probabilistic module? 30

31 Use of the probabilistic module 31

32 Use of probabilistic module 32

33 Use of probabilistic module 33

34 Use of probabilistic module 34

35 Use of probabilistic software 35

36 Use of probabilistic software 36

37 Result 37

38 38

39 Characteristics of the product: physico-chemical characteristics, preservatives content, type of packaging, process, foreseen shelf-life. Available scientific literature and research data regarding the growth and survival characteristics of the micro-organisms of concern. Predictive microbiology Durability studies And, when necessary, When necessary: to implement laboratory tests. Challenge tests.

40 The durability study Test used to assess the growth of L. m in a food : Naturally contaminated Stored at foreseeable conditions (temperature/time) from production to consumption. It is a checking at foreseeable conditions of temperature and duration.

41 How to use durability studies? All the results may be pooled. Final result = Proportion of units exceeding 100 cfu/g at the end of the shelf-life. "n" Number of units analysed "r" Number of units 100 ufc/g "p" Estimated proportion (Confidence Interval at 95 %) 5 0 [0% - 46%] 10 0 [0% - 28%] 15 0 [0% - 21%] 20 0 [0% - 16%] 25 0 [0% - 13%] 30 0 [0% - 11%] [0% - 9.7%] 40 0 [0% -8.6%] 45 0 [0% - 7.7%] [0% - 3.8%] [0% - 2.9%]

42 Laboratory test used to assess the growth rate of a bacteria in a food: Artificially contaminated Stored at a fixed temperature. Exponential phase µ max : " daily growth rate of the bacteria". Lag phase (days)

43 How to use the µ max? D0 D1 D2 For a RTE food with a shelf-life of 10 days D3 D4 D5 D6 D7 D8 [L. m] = 1.8 log cfu/g µ max = 0.20 d -1 at 8 C D9 D log cfu/g [L. m] = 2.4 log cfu/g 2 log cfu/g

44 Laboratory test used for the estimation of the growth of a bacteria in a food: Artificially contaminated Stored under foreseeable conditions from production to consumption. The growth potential can be used: To determine if a food permits the growth of L. m To set up the concentration of L. m at the end of the shelf life according to the concentration at the plant To set up the concentration at the production according to the limit of 100 cfu/g at the end of the shelf life.

45 How to use the growth potential (0.68 log cfu/g)? Initial concentration of L. m = 1 log cfu/g Growth potentiel (δ) = 0.68 log cfu/g + Final concentration of L. m = 1.68 log cfu/g < 2 log cfu/g

46 o EU RL for L. m has written a document listing the points to be checked to be sure that CT assessing growth potential are implemented according to the technical guidance document. o The document is named: Guidance document to evaluate the competence of laboratories implementing challenge tests on the growth potential of L. m in RTE foods " o It was written in collaboration with representatives of 12 NRLs for L. m from Belgium, Cyprus, Czech Republic, Denmark, Ireland, Latvia, Norway, Portugal, Slovenia, Spain, Sweden, The Netherlands.

47 o Either experts basing their opinion on documents. o Or auditors conducting audits in laboratories.

48 o The laboratory has to be accredited according to ISO 17025, for the detection and enumeration of L. monocytogenes. o The laboratory has to get satisfactory results from PT trials for parameters such as ph, a w, preservatives, microflora,

49 Packaging conditions Air, vacuum, MA Characterization of the cold chain Temperature distributions Process Flow diagram Scientific literature Growth ability, Physico-chemical characteristics ph, a w, microflora, preservatives Description and composition of the product Shelf-life, Storage temperature This data justifies the decision to perform or not the CT. Predictive microbiology Growth probability, Growth simulation Historical data Prevalence, Enumeration This data will help the laboratory to perform the CT.

50 Preparation of the inoculum Number/ source of the strains, Preparation of the subcultures and inoculum Inoculation of the samples Part to be contaminated, Method and level of inoculation of inoculation Information about batches Number, Representativeness This data is compared to the technical guidance document specifications. Storage conditions of the samples Temperature distributions, or temperatures proposed by the EU

51 Enumerations of L. m in the at D 0 and D end in the inoculated samples Enumeration method, Enumeration threshold Calculation of the growth potential Concentration of L. m at D 0 and D end, Calculation of the growth potential Use of the results Classification of the RTE food, Calculation of the [L. m] at the plant Characterization of the RTE food Physical-chemical characteristics, Enumeration of associated flora, Blank L. m detection/concentration This data is compared to the technical guidance document specifications. Test report Report number, Accreditation logo, Data related to the food Data related to the CT

52 o The laboratory is able to perform challenge tests assessing the growth potential YES NO o The laboratory will be able to perform challenge tests provided that improvements are made on few points:

53 To constitute a collection of strains from various origins (meat, dairy products, fish, ) and various serotypes selected for their ability to grow rapidly and to grow in harsh conditions of temperature, ph and a w. The strains collection will be available for each NRL for L. monocytogenes. To prepare a new version of the Technical Guidance Document (TGD) on shelf-life studies for L. monocytogenes in ready-to-eat foods.

54 Thank you for your attention!