Analysis of process factors of dry fermented salami to control Listeria monocytogenes

Challenge tests are a clear opportunity for manufacturers interested in the evaluation of their management system with the aim to reduce the spread of foodborne pathogens. This is a main concern especially in ready-to-eat food in relation to the risk associated with Listeria monocytogenes. For small and medium-scale food industry the manufacturing practices and products formulation are characterized by a wider variability and poor repeatability. The use of ad-hoc challenge test and the comparison among different processing systems are strongly required. This paper reports a preliminary comparison among different challenge tests (n=12) commissioned by three manufacturers of raw-fermented Salami during a period of three years (2013-2016). The challenge tests were designed to evaluate the growth potential (δ) of L. monocytogenes during the whole processing period of the Salami. The doughs were prepared according to different formulations: the simplest formulation was represented by the use of salt, potassium nitrate, black pepper and starter cultures while the most composited formulations also included the use of sugars and ascorbic acid in addition to nitrite salt. All the processing steps were conducted within an experimental laboratory dedicated for the processing of meat. After stuffing the salami were dried and ripened under temperature and relative humidity control. The sugar inclusion can be considered as protective factor, while the drying step at high temperature (above 20°C) was associated with higher δ values (δ>0.5 log cfu/g). The addition of starter cultures, and the subsequent acidification highlighted the importance of pH as the parameter able to affect the L. monocytogenes growth.

Download Full-text

Growth Potential of Listeria monocytogenes in Three Different Salmon Products

Foods ◽

10.3390/foods9081048 ◽

2020 ◽

Vol 9 (8) ◽

pp. 1048 ◽

Cited By ~ 2

Author(s):

Corinne Eicher ◽

Andres Ruiz Subira ◽

Sabrina Corti ◽

Arnulf Meusburger ◽

Roger Stephan ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Challenge Test ◽

High Growth ◽

Growth Potential ◽

High Concentration ◽

Food Borne ◽

Smoked Salmon ◽

Good Manufacturing Practices ◽

Challenge Tests ◽

Low Levels

Cold smoked salmon and sushi salmon have been implicated in outbreaks of listeriosis. We performed challenge tests and a durability study with Listeria monocytogenes on different salmon products to determine the growth potential of this important food-borne pathogen. Data from the challenge test showed a significant growth potential of L. monocytogenes on all of the tested salmon products, with faster growth in sushi salmon than in cold smoked salmon. In identical products that were naturally contaminated at low levels, the durability study did not confirm a high growth potential, possibly due to interactions with competing microflora. The injection of sodium lactate (NaL) at a high concentration (30%) into cold smoked salmon significantly reduced the growth potential of L. monocytogenes. In addition to good manufacturing practices, the injection of higher concentrations of NaL may therefore be a useful additional hurdle to prevent growth of L. monocytogenes to high numbers in the tested salmon products.

Download Full-text

Challenge Test as Special Tool to Estimate the Dynamic of Listeria monocytogenes and Other Foodborne Pathogens

Foods ◽

10.3390/foods11010032 ◽

2021 ◽

Vol 11 (1) ◽

pp. 32

Author(s):

Luigi Lanni ◽

Valeria Morena ◽

Adriana Scattareggia Marchese ◽

Gessica Destro ◽

Marcello Ferioli ◽

...

Keyword(s):

European Union ◽

Listeria Monocytogenes ◽

Foodborne Pathogens ◽

Challenge Test ◽

Growth Potential ◽

Economic Losses ◽

Hospital Treatment ◽

The European Union ◽

Advantages And Disadvantages ◽

Challenge Tests

Over 23 million cases of foodborne disease (FBD) occur in Europe each year, with over 4700 deaths. Outbreaks of FBD have a significant impact on our society due to the high economic losses they cause (hospital treatment of affected patients and destruction of contaminated food). Among its health objectives, the European Union has set itself the goal of reducing the incidence of the main FBDs, approving various regulations that codify requirements in order to produce food that is “safe” for human consumption. Among these rules, Regulation 2005/2073 establishes precise food safety criteria for foods that are judged to be most at risk of causing episodes of FBD. The food business operator (FBO) must know their food better and know how to estimate whether a food can support the growth of food pathogens or if they are able to hinder it during the food’s shelf life. It is becoming crucial for each FBO to schedule specific laboratory tests (challenge tests) to establish the growth potential of individual pathogens and their maximum growth rate. In 2008 the European Union published the guidelines for programming the challenge tests for Listeria monocytogenes in RTE foods. These guidelines were further implemented in 2014 and again in 2019. In June 2019 the UNI EN ISO 20976-1 was published, which contains indications for setting up and carrying out challenge tests for all foodborne pathogens in all foods. In this article, we compare the three official documents to highlight their common aspects and differences, highlighting the advantages and disadvantages that each of them offers for those who have to set up a challenge test for the various foodborne pathogens. Our conclusion is that the challenge test is today the most effective tool to estimate the dynamics and growth potential of pathogenic microorganisms in food, if it is designed and implemented in a scrupulous way. It is important to develop a rational experimental design for each challenge test, and for each food, and this requires professionals who are experts in this specific field of study and who must be properly trained.

Download Full-text

Evaluation of growth potential and growth dynamics of Listeria monocytogenes on ready-to-eat fresh fruit

Italian Journal of Food Safety ◽

10.4081/ijfs.2021.9337 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

David Collu ◽

Luisa Marras ◽

Adriana Sanna ◽

Gerolamo Carrucciu ◽

Antonella Pinna ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Challenge Test ◽

Growth Dynamics ◽

Food Product ◽

Growth Potential ◽

Salmonella Spp ◽

E Coli ◽

Hygiene Practices ◽

Short Period ◽

Challenge Tests

The consumption of fresh or RTE fruits is increasing every year and Listeria monocytogenes has been identified on raw or minimally processed fruits. A food product can become contaminated with L. monocytogenes anywhere along the pathway of food production during planting, harvesting, packaging, distribution and serving. The aim of this work was to assess the microbiological risks associated with consumption of ready- to- eat fruit such as melon, pineapple, coconut and fruit salad. The presence of Escherichia coli, Salmonella spp. and L. monocytogenes was also evaluated. Microbiological challenge tests were carried out for the evaluation of the L. monocytogenes growth potential in RTE fruit stored at 4 and 8°C. E. coli counts resulted under the detection limit of 10 CFU g-1, Salmonella and L. monocytogenes were not detected (absence in 25g). The growth potential values in coconut and melon (δ>0.5) showed the growth capacity of Listeria at the temperatures considered. A low initial load, also derived from good hygiene practices, and correct storage temperatures are essential to reduce bacterial growth in RTE fruit. The challenge test showed how each type of RTE fruit has a different commercial life based on its specific growth potential and that food should be stored at temperatures not higher than 4°C for a short period.

Download Full-text

Thermal inactivation and growth potential of Listeria monocytogenes in smoked tench

Italian Journal of Food Safety ◽

10.4081/ijfs.2016.5974 ◽

2016 ◽

Vol 5 (3) ◽

Cited By ~ 2

Author(s):

Raffaella Branciari ◽

Andrea Valiani ◽

Raffaella Franceschini ◽

David Ranucci ◽

Alessia Lupattelli ◽

...

Keyword(s):

Experimental Study ◽

Listeria Monocytogenes ◽

Thermal Inactivation ◽

Challenge Test ◽

Listeria Innocua ◽

Growth Potential ◽

Post Processing ◽

Colony Forming Unit ◽

Post Process ◽

Hygiene Measures

An experimental study for the evaluation of Listeria monocytogenes inactivation during a hot smoking process in tench was performed using Listeria innocua strains. Furthermore, the survival of L. monocytogenes in smoked tench was determined after post-processing in contaminated samples, evaluating the growth potential during storage. L. innocua was not detected after the smoking process. In the challenge test, the growth potential of L. monocytogenes was 5.68 log colony forming unit g−1. The results showed that hot smoking at an inner temperature around 72°C is able to eliminate the microorganism. Nevertheless, the product is able to support the growth of the pathogen if post-process contamination occurs, as the food is suitable for Listeria multiplication. Product recontamination should be prevented by means of appropriate application of hygiene measures.

Download Full-text

Determination of the growth potential of Listeria monocytogenes in various types of Belgian artisanal cheeses by challenge tests

Food Microbiology ◽

10.1016/j.fm.2020.103582 ◽

2020 ◽

Vol 92 ◽

pp. 103582

Author(s):

Amaury Gérard ◽

Soundous El-Hajjaji ◽

Els Van Coillie ◽

Azeddine Bentaïb ◽

Georges Daube ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Growth Potential ◽

Challenge Tests

Download Full-text

Growth potential of Listeria monocytogenes in veal tartare

Italian Journal of Food Safety ◽

10.4081/ijfs.2021.9419 ◽

2021 ◽

Vol 10 (3) ◽

Author(s):

Simone Stella ◽

Cristian Bernardi ◽

Erica Tirloni

Keyword(s):

Lactic Acid ◽

Listeria Monocytogenes ◽

Lactic Acid Bacteria ◽

Shelf Life ◽

Challenge Test ◽

Growth Potential ◽

Daily Maximum ◽

Initial Concentration ◽

Spoilage Bacteria ◽

Sampling Times

In the present study the growth potential of Listeria monocytogenes in veal tartare was evaluated. A challenge test was performed on three tartare batches at 8°C, aiming to evaluate the growth potential of the pathogen. The data indicated the absence of a significant growth (δ<0.5 log cfu/g) during the entire period. When considering intermediate sampling times, an increase of 0.56 log cfu/g was detected after five days of storage in one of the batches. Microflora of veal tartare was dominated by lactic acid bacteria, that increased gradually during the trial, reaching counts up to 7 Log CFU/g in two of the three batches considered. Spoilage bacteria were present (especially Pseudomonas spp., yeasts and Enterobacteriaceae) but in very low counts and with a limited increase during the period considered. Finally, daily maximum tolerable L. monocytogenes counts were calculated to highlight the maximum acceptable load to avoid the overcoming of the legal limit of 100 CFU/g: a total increase of 0.95 log cfu/g in 12 days of shelf-life was estimated, obtaining a “safety initial concentration” at t0 of 10 CFU/g of the pathogen.

Download Full-text

Definition of a standard protocol to determine the growth potential of Listeria monocytogenes and Yersinia enterocolitica in pork sausage produced in Abruzzo Region, Italy

Italian Journal of Food Safety ◽

10.4081/ijfs.2015.4575 ◽

2015 ◽

Vol 4 (4) ◽

Author(s):

Anna Franca Sperandii ◽

Diana Neri ◽

Romina Romantini ◽

Gino Angelo Santarelli ◽

Vincenza Prencipe

Keyword(s):

Listeria Monocytogenes ◽

Yersinia Enterocolitica ◽

Growth Potential ◽

Standard Protocol ◽

Pathogenic Microorganisms ◽

Pork Meat ◽

Pork Sausage ◽

Italian Regions ◽

Short Period ◽

Challenge Tests

Pork meat products consumed raw or after a short period of fermentation can be considered at risk for food safety (EFSA 2010). Sausages (fresh sausage made from pork meat) are produced in several Italian regions, with variation in ingredients. In some Italian Regions, including Abruzzo, these products are frequently consumed raw or undercooked, after a variable period of fermentation. The EU food regulation promotes the use of challenge tests to determinate safety levels. This study is aimed to ensure safety of Abruzzo’s sausages, compared with growth potential (δ) of Listeria monocytogenes and Yersinia enterocolitica and also aims to define an experimental standard protocol document to carry out challenge tests. Guidelines classify foods ready to eat in categories that are able to support (δ>0.5 log10 ufc/g) and not support (δ≤0.5 log10 ufc/g) the growth of Listeria monocytogenes. The products were manufactured according to traditional recipe and were contaminated in laboratory. Results from the experiment yielded information useful to assess the ability of these products to support the growth of pathogenic microorganisms. The batches of sausages were stored at 8, 12, 18 and 20°C to get statistical evaluation. The results showed that, despite the conditioning of the storage temperature and the level of aw, both organisms remain in the product in concentrations similar to those leading or are able to increase its charge. In particular the period of greatest consumption of this product (7/8 days of preparation) corresponds to the period of greatest growth of pathogenic microorganisms studied, except for those stored at a temperature of 8° C, which are safer for the consumer.

Download Full-text