CHALLENGE TESTING IN AN ACCREDITED LABORATORY

In a chal­lenge test, the growth and death behavior of a pathogen in a product is docu­mented and all proce­dures for ensuring product quality in the manu­fac­turing process are crit­i­cally exam­ined. For this purpose, the starting or finished product is arti­fi­cially cont­a­m­i­nated with the pathogen to be inves­ti­gated and stored until the best-before date.
After inoc­u­la­tion and on the day of the best-before date, as well as at least 3 times during storage, the content of the target pathogen is determined.

In a chal­lenge test, various process para­me­ters and their influ­ence on the bacte­rial count are investigated.

• Influ­ence of storage condi­tions: It can be checked whether the currently selected storage condi­tions have an influ­ence on the germ counts. That is, it is inves­ti­gated whether growth is inhib­ited, delayed or favored.
• Effec­tive­ness of thermal treat­ment: Many foods are made more durable with thermal treat­ment processes such as pasteur­iza­tion and ster­il­iza­tion. Chal­lenge testing can be used to deter­mine the extent to which this process affects the ability of prod­ucts to multiply pathogens.
• Effec­tive­ness of the use of food addi­tives: Addi­tives, such as preser­v­a­tives and antiox­i­dants, are also used to extend shelf life in food prod­ucts. The effec­tive­ness of the use of these addi­tives is veri­fied by chal­lenge tests.
• Effec­tive­ness of protec­tive and starter cultures: Bacte­rial protec­tive and starter cultures are used for chem­ical preser­va­tion and are intended to prevent unde­sired prolif­er­a­tion of microor­gan­isms, which can be tested by a chal­lenge test.
• Influ­ence of special pack­aging on food: Antibac­te­rial pack­aging or pack­aging of food under protec­tive gas atmos­phere slows down the aging of food and thus prolongs shelf life. The influ­ence of different pack­aging can be inves­ti­gated by chal­lenge test.

After a challenge test is completed, it is carefully evaluated. The test results can confirm that the product favors or inhibits the growth of the target germ. Conclusions can thus be drawn about the required storage conditions and the manufacturing process. Adjustments to food safety may then have to be made here, as pathogenic microorganisms and spoilage agents have multiplied.

In order to avoid recalls of your prod­ucts in the future and to ensure the required food safety, we support you with our many years of expe­ri­ence in chal­lenge testing. As an accred­ited labo­ra­tory, we offer you the plan­ning, execu­tion and eval­u­a­tion of chal­lenge tests for all produc­tion steps in accor­dance with the guide­lines published by an EU refer­ence labo­ra­tory, so that your prod­ucts do not have to be recalled due to contamination.

Chal­lenge tests must always be carried out under iden­tical condi­tions to those in the actual produc­tion process in order to make reli­able state­ments. For this purpose, we either receive the required samples from various steps of the produc­tion process from you, or we recreate the entire produc­tion process 1:1 in our pilot plant.

In order to be able to make specific state­ments about shelf life, product safety and neces­sary opti­miza­tions in the produc­tion process, we repro­duce the complete produc­tion line of our customers for the produc­tion of e.g. raw sausage in our labo­ra­tory on a small scale. For this purpose, we have set up a pilot plant in which all your produc­tion steps are precisely simu­lated using state-of-the-art equipment.

At selected produc­tion steps, such as the comminu­tion of the raw sausage, the mincing, the filling or the ripening process, the raw sausage is inoc­u­lated with L. mono­cy­to­genes (or another germ to be exam­ined). With the aid of this proce­dure, we can deter­mine whether the microor­gan­isms to be inves­ti­gated multiply, are inhib­ited or even reduced in the course of further produc­tion or ripening.

We perform chal­lenge tests for the following pathogens and spoilage organisms:

• L. mono­cy­to­genes
• Enter­obac­te­ri­aceae
• Lactic acid bacteria
• Yeasts and molds

FURTHER LITER­A­TURE:
EURL Lm TECH­NICAL GUID­ANCE DOCU­MENT for conduc­ting shelf-life studies on Listeria mono­cy­to­genes in ready-to-eat foods

This docu­ment describes labo­ra­tory studies, chal­lenge tests and shelf-life studies related to the growth of L. mono­cy­to­genes in ready-to-eat foods. The bilacon provides chal­lenge tests in accor­dance with this guide­line for conducting shelf-life studies.

Before a chal­lenge test can be performed, a prelim­i­nary discus­sion is held to iden­tify the factors that may affect the growth of the microor­gan­isms. The produc­tion steps are disclosed and the storage condi­tions, the exact compo­si­tion, the best-before date, as well as the pack­aging of the product are discussed in order to provide you with compre­hen­sive advice regarding the test.

In addi­tion, it is deter­mined in advance how many batches are to be tested and on how many test dates. For ready-to-eat foods, for example, at least 3 batches should be tested.

a) Chal­lenge test in your produc­tion unit

If you choose this option, the produc­tion of your food takes place in your own produc­tion unit. You take samples at prede­fined points in the produc­tion, which we examine in our laboratories.

b) Chal­lenge test in our pilot plant

In order to make very specific state­ments, we bring your entire produc­tion process to our labo­ra­tory. In our specially equipped pilot plant, the entire produc­tion process is simu­lated and the food is produced under these condi­tions. The food is arti­fi­cially cont­a­m­i­nated with the desired microor­ganism either at certain produc­tion steps or after completion.

The product is then stored under the desired condi­tions until the end of the shelf life and micro­bi­o­log­i­cally exam­ined at the agreed exam­i­na­tion times. For compar­ison, the uninoc­u­lated sample is always exam­ined as well.

Finally, you will receive a detailed test report with the analysis results, as well as an eval­u­a­tion of the results.

After confir­ma­tion of the offer, at least two weeks are needed for plan­ning and prepa­ra­tion of the exam­i­na­tion. In case special refer­ence strains are needed, they have to be ordered in advance. This can take an addi­tional one to two weeks depending on the delivery time.

After the start of the chal­lenge test, the prod­ucts are stored until the end of the best-before date of the respec­tive product. Two weeks are required after the end of the chal­lenge test to eval­uate the results and prepare the report.

Generally, one challenge test per product is sufficient. However, if the recipe of the product, the production process or the storage conditions change, a new challenge test must be performed.

After the start of the challenge test, the products are stored until the end of the best-before date of the respective product. Two weeks are required after the end of the challenge test to evaluate the results and prepare the report.

Tobias Stapper
Head of Microbiology
tobias.​stapper@​tentamus.​com
+49 30 206 038 370

Benjamin Ebel
Customer Advisor Meat & Meat Products
benjamin.​ebel@​tentamus.​com
+49 30 206 038 139