Call for experts: milk analysis

MicroVal is an international organisation for the validation of alternative methods in food and water microbiology. The basis for these validation studies is the ISO 16140 series. The first MicroVal certificate dates back from 2007. Since then, more than 70 test kits and methods by manufactures in North America, Asia and Europe, have been successfully validated and resulted in a MicroVal certificate.

Recently, there has been an increase in the demand for the validation of methods for milk analysis and more specifically somatic cell count and total bacterial count. These studies require additional validation based on IDF standards (e.g. ISO 8196, ISO 13366, ISO 16297). Therefore, MicroVal will establish a working group that specifically focusses on these validation studies. In order to start this working group, MicroVal is looking for experts with experience and knowledge of methods for milk analysis (cow, sheep, goat, etc.) and the relevant ISO standards.

Experts who’s experience matches with the requirements below, are invited to apply for joining the MicroVal team.

Advantages:

  • Keep up to date with newly developed methods for milk analysis;
  • Involvement with the validation processes and evaluation of test results;
  • Knowledge of the use and performance of new methods based on their method validation; 
  • Be part of an international network, consisting of manufacturers, researchers and standardization/validation experts, contributing to the quality assurance of analytical methods.

Requirements:

  • Fluent in English.
  • General scientific training in (dairy) microbiology;
  • A minimum of five years of recent experience in an organization involved in food/dairy microbiology, including working within an ISO 17025 accredited quality management system;
  • Knowledge and experience in working with ISO reference methods for somatic cell count and total bacterial count, such as:
ISO 13366-1|
IDF 148-1
Milk – Enumeration of somatic cells – Part 1: Microscopic method
ISO 4833-1Microbiology of the food chain – Horizontal method for the enumeration of microorganisms – Part 1: Colony count at 30 °C by the pour plate technique
ISO 4833-2Microbiology of the food chain – Horizontal method for the enumeration of microorganisms – Part 2: Colony count at 30 degrees C by the surface plating technique

Knowledge and experience in method validation and validation standards, such as:

ISO 8196-3|
IDF 128-3
Milk – Definition and evaluation of the overall accuracy of alternative methods of milk analysis — Part 3: Protocol for the evaluation and validation of alternative quantitative methods of milk analysis
ISO 13366-2|
IDF 148-2
Milk – Enumeration of somatic cells – Part 2: Guidance on the operation of fluoro-optoelectronic counters
ISO 16297|
IDF 161
Milk – Bacterial count — Protocol for the evaluation of alternative methods
ISO 21187|
IDF 196
Milk — Quantitative determination of microbiological quality — Guidance for establishing and verifying a conversion relationship between results of an alternative method and anchor method results

Expectations:

The following is expected from the experts joining the MicroVal team for the validation of methods for milk analysis:

  • Contribute to the reviewing work, which consists of:
    • Reviewing of protocols and reports of ongoing validation studies;
    • Reviewing of modifications and extension studies;
    • Evaluation of certificate renewal requests;
  • Participate in online two-hours meetings, which take place max. 4 times per year;
  • Contribute on a voluntary basis as MicroVal is a non-profit organisation;
  • Maintain confidentiality – a non-disclosure agreement is signed by all MicroVal members.

 

Application:

Interested candidates are invited to submit their application, containing the following information:

  • Your motivation;
  • A recent resume including supporting information on meeting the above requirements;
  • Contact details.

Applications can be sent to microval@nen.nl before March 15th, 2023. Also questions concerning the application procedure can be sent to the email above. More information about MicroVal and its procedures can be found in the MicroVal Rules, the certification scheme of MicroVal. The MicroVal secretariat is run by NEN, the Royal Netherlands Standardization Institute.

New ISO 16140-6 validation for Check&Trace Salmonella 2.0

MicroVal has approved the issuing of the certificate for Check-Points’s Check&Trace Salmonella 2.0. WFC Analytics carried out the validation study, based on ISO 16140-6, for an alternative method for the confirmation and typing of Salmonella spp. Following from the validation study, the Check&Trace Salmonella 2.0 (CTS 2.0) is considered equivalent to the reference method (ISO 6579-1 and ISO 6579-3) for the confirmation of presumptive Salmonella spp. isolated on non-selective NA and selective XLD and for typing of 59 Salmonella serovars.

The Check&Trace Salmonella 2.0 Assay is a qualitative, semi-automated real-time PCR test designed for the confirmation and typing of presumptive Salmonella isolates from enriched culture media. The confirmation procedure advances a suspected (presumptive) Salmonella result to a confirmed Salmonella spp. result or a Salmonella negative result. The typing procedure generates a serovar result or a “genovar” code both uniquely defining each bacterial isolate tested.

DNA typing differs from serotyping. With serotyping the presence of antigens on the cell surface and flagella are detected. This is based on expression of genes located on two specific segments of the Salmonella genome. The CTS 2.0 assay detects genetic variation at 21 loci scattered over the whole Salmonella genome: this generates specific Salmonella genotypes, also called Genovars. The CTS 2.0 database links Genovars to a collection of well-characterized Salmonella Serovars. A Genovar will be given as test result if there is no established Serovar for the Genovar generated by the CTS 2.0 assay.

Check&Trace Salmonella 2.0 is considered equivalent to the ISO standard (ISO/TR 6579-3:2014) for typing of 59 Salmonella serovars. The full list of Salmonella serovars is given in the certificate and validation report, available on the MicroVal website under ‘issued certificates / confirmation methods’.

Renewed certificate for iQ-Check STEC VirX

In December 2022, MicroVal has approved the issuing of the renewed certificate for Bio-Rad’s  iQ Check STEC VirX, based on the extension validation study to include food products based flours and raw doughs within the scope. Like the initial validation study, also the extension study was carried out by ADRIA Développement.

The iQ-Check STEC VirX for real-time PCR detection of virulence genes in Shiga toxin-producing Escherichia coli has now been validated for raw dairy products, raw meat products (excluding poultry) and flours and raw doughs. In general, this method gives the results for both stx and eae genes, however for this validation study, the interpretation was based on detection of stx only.

The certificate and the accompanying validation report, number 2021LR96, can be found under ‘issued certificates / alternative methods’.

First MicroVal certificate for MCS Diagnostics’ CertaBlue detection method

In September 2022, MicroVal has approved the issuing of the certificate for MCS Diagnostics’ CertaBlue TVC for the detection of Total Viable Count. WFC has carried out the validation study of this rapid method, based on ISO 16140-2:2016, for the scope of broad range of foods and environmental samples. To obtain the broad range of foods claim, the following categories were included in the validation study:

  • Milk and dairy products (raw and heat-processed)
  • Meat and meat products and poultry and poultry products (raw, ready-to-cook and ready-to-eat, ready-to-reheat)
  • Ready-to-cook fish and seafoods and ready-to-eat, ready-to-reheat fishery products
  • Processed fruits and vegetables
  • Bakery products and multi-component foods or meal components

The CertaBlue TVC test is designed to rapidly detect microbial contaminations. An inoculated vial is placed into the AutoScanner System, where it is incubated and monitored in real time. If growth is detected, the sample fails; if there is no detection, the sample passes (i.e., the counts are below the specification limit).

In the validation study, the CertaBlue TVC has been compared to the ISO 4833-1:2013. Although the reference method is generally used to enumerate the level of microorganisms, in this validation it was used to establish if levels of microorganisms exceed the defined threshold of 1 cfu per g for liquid products, 1 cfu per swab for swabs and 10 cfu per g for other products. Thus, a qualitative presence/absence approach with a set presence/absence limit was used, where presence of a single colony (solid and semi-solid products always require a 1:10 dilution step) was equivalent to a “detected” result and absence of a single colony was equivalent to a “not detected” result.

The certificate and the accompanying summary report, number 2021LR94, can be found on the website under ‘issued certificates / alternative methods’.

First MicroVal certificate for commercial sterility detection method

MicroVal has recently issued the certificate for Neogen’s Soleris Commercial Sterility Testing Vials (NF-105) for the determination of commercial sterility in UHT treated milk and dairy alternative plant drinks. These are ready-to-use media vials containing a broth able to grow aerobic, mesophilic microorganisms (bacteria, yeasts and moulds) that are able to grow on an aerobic plate count at 30°C. Results from the validation data showed that the alternative method can be used as a rapid and sensitive testing method for commercial sterility monitoring of UHT treated milk and dairy alternative drinks.

Campden BRI has carried out the validation study of this alternative method, based on ISO 16140-2:2016. The Soleris NF-105 testing vial has been validated against the Codex Alimentarius, Code of Hygienic practice for milk and milk products (CAC/RCP 57-2004), Annex B Microbiocidal control measures Section 2.2 process management for UHT treatment using ISO 4833-1:2013 for the plate count at 30°C. In this validation, the method was used to determine a defined threshold of product contamination of greater than ≤ 10cfu per 0.1ml as defined in the European Directive 92/46 annex C chapter 2 for ultra-high temperature (UHT) milk.

The certificate and the accompanying summary report, number 2021LR100, can be found under ‘issued certificates / alternative methods’.

New Certificate for iQ-Check™ STEC VirX

In June 2022, MicroVal has approved the issuing of the certificate for Bio-Rad’s iQ-Check™ STEC VirX kit for real-time PCR detection of virulence genes in Shiga toxin-producing Escherichia coli. ADRIA Développement has carried out the validation study of this alternative method, based on ISO 16140-2:2016, for the scope of raw meat products (excluding poultry) and raw dairy products.

STEC outbreaks are commonly associated with the consumption of raw meat, particularly beef, but also with dairy products. A sample positive for both stx1/stx2 and eae targets typically requires further testing for the identification of the major E. coli serogroups. The iQ-Check STEC VirX Kit, based on a multiplex real-time PCR system, allows the detection of the stx1/stx2 and eae virulence genes within a few hours after microbiological enrichment.

The certificate and the accompanying validation report, number 2021LR96, can be found under ‘issued certificates / alternative methods’.

Twelfth certificate for Nissui’s Compact Dry

MicroVal has approved the issuing of the certificate for Compact Dry LM by Nissui. This is a chromogenic medium for the detection and enumeration of Listeria Monocytogenes. Campden BRI has carried out the validation study of this alternative method, based on ISO 16140-2:2016, for the scope broad range of foods, consisting of the following categories, plus environmental samples:

  1. Meat and poultry products (RTE/RTRH)
  2. Dairy products (raw and heat processed)
  3. Fresh produce and fruit
  4. Seafood & fishery products
  5. Multicomponent foods

The Compact Dry LM has been validated against ISO 11290-1 and against ISO 11290-2. This extensive validation study has resulted in two separate certificates for the detection of Listeria Monocytogenes  and for the enumeration of this species. Both certificates, numbers 2020LR91a+b can be found under ‘issued certificates / alternative methods’.

During the past years, MicroVal has already validated and certified the Compact Dry chromogenic medium for:

  • Bacillus cereus – Compact Dry BC (2019LR87)
  • E. coli – Compact Dry EC (2008LR04/05, previously MV0806-004LR & MV0806-005LR)
  • Enterobacteriaceae – Compact Dry ETB (2008LR02, previously MV0806-002LR)
  • Enterococcus – Compact Dry ETC (2014LR48)
  • Pseudomonas aeruginosa – Compact Dry PA (2017LR66)
  • Staphylococcus aureus – Compact Dry X-SA (2008LR14)
  • Total coliforms – Compact Dry CF (2008LR03, previously MV0806-003LR)
  • Total viable count – Compact Dry TC (2007LR01)
  • Yeast & moulds – Compact Dry YM (2008LR10, previously RQA2008LR10)
  • Yeast & moulds – Compact Dry YMr (2016LR61)

New certificate for foodproof Enterobacteriaceae plus Salmonella Detection LyoKit – 5’Nuclease

MicroVal has approved the issuing of the certificate for BIOTECON diagnostics GmbH’s foodproof Enterobacteriaceae plus Salmonella Detection LyoKit – 5’Nuclease. The validation study is carried out ADRIA Développement and is based on ISO 16140-2:2016.

The foodproof Enterobacteriaceae plus Salmonella Detection LyoKit – 5’Nuclease is a PCR kit for the qualitative detection of Enterobacteriaceae plus simultaneous identification of Salmonella spp. DNA using real-time PCR instruments. The validation of this alternative method has been performed in combination with the foodproof StarPrep One Kit and the foodproof StarPrep Three Kit in both single tube and 8-strip formats. For this validation study the following categories were tested:

  • infant cereals,
  • infant formula with or without probiotics and ingredients
  • production environmental samples.

The certificate and the accompanying study report, number 2020LR90, can be found under ‘issued certificates / alternative methods’.

New certificate for Kylt Salmonella spp. 2.0

MicroVal has approved the issuing of the certificate for Kylt Salmonella spp. 2.0 by AniCon Labor GmbH. Campden BRI has carried out the validation study of this alternative method, based on ISO 16140-2:2016, for the detection of Salmonella spp in 4 different categories:

  1. Raw meat and ready to cook meat products,
  2. Raw poultry and ready to cook poultry products,
  3. Environmental samples and
  4. Primary production samples.

Kylt Salmonella spp. 2.0 has been validated against ISO 6579- 1:2017 (Horizontal method for the detection, enumeration and serotyping of Salmonella. Part 1: Detection of Salmonella spp.)

Kylt Salmonella spp. 2.0 a polymerase chain reaction (PCR) based assay that targets Salmonella specific DNA split into 3 stages:

  1. Sample enrichment in Buffered Peptone Water (BPW) prewarmed to 37°C and incubated for 16h at 37 ±1°C.
  2. DNA extraction using 1 of the 2 DNA extraction methods listed in the manufacturer’s protocol
  3. Analysis of DNA extracts by real time PCR using selected PCR platforms. The study evaluated 2 PCR programmes for Salmonella detection;

The certificate and the accompanying study report, number 2017LR78, can be found under ‘issued certificates / alternative methods’.

New certificate issued for Neogen’s One Plate Listeria

MicroVal has approved the issuing of the certificate for Neogen’s One Plate Listeria (OP-L). Campden BRI has carried out the validation study of this alternative method, based on ISO 16140-2:2016, for the enumeration of two different targets, Listeria monocytogenes and Listeria spp., against the reference method ISO 11290- 2:2017. The method, One Plate Listeria, has been validated for the scope of a broad range of foods.

One plate Listeria (OP-L) is a chromogenic medium for the enumeration of Listeria spp. and L. monocytogenes. Characteristic colonies of L. monocytogenes appear blue to blue-green and are surrounded by an opaque halo. Characteristic colonies of Listeria spp appear blue to blue-green with or without an opaque halo. This method has the option to enumerate the target organsism in different plating formats – 1ml pour plate and 0.1ml spread plate.

The certificate and the accompanying summary report, number 2019LR89, can be found under ‘issued certificates / alternative methods’.