Food Microbiology: How to Become a Quality Control Freak

Disinfectant verification: Production environments, including food contact surfaces and air, are well-known sources of contamination and should be closely monitored for minimize the risk of post-processing contamination of products. Environmental monitoring and trending data will provide a good assessment of the microorganism strains that are found most often in your facility. This information, along with a disinfectant qualification study, will help to make clear which chemical agents are best for removing environmental microorganisms.

Disinfectant effectiveness should be verified for each potential disinfectant before being put to use. Challenge micro- organisms for disinfectant qualification should include both reference cultures and environmental isolates. Disinfectant qualification is commonly done by inoculating surfaces with a sample that simulates the contamination that would occur during work sessions. After the disinfectant has been used on the inoculated surface, contact plate testing is done to determine whether or not the disinfection was effective.

Proficiency: Quality of test results is dependent on the quality of the people performing the test. Proficiency testing is an integral part of laboratory activities. The ISO/IEC 17025 standard requires proficiency testing activities for all tests listed in the establishment’s scope of accreditation. The purpose of this testing is to ensure that each accredited laboratory is capable of conducting tests and producing data in an accurate and repeatable manner. Laboratory competence can be demonstrated to customers, potential customers, and accrediting bodies through the presentation of proficiency testing data. A regular proficiency testing schedule helps to identify problem areas before they affect the quality or safety of products.

Karla I. Fjeld is technical manager at Microbiologics in St. Cloud, Minn., overseeing all laboratory matters. She received a PhD in biochemistry and molecular biology at Michigan State University.

Choose a Supplier of Reference Materials

Biological reference materials are used to assure the quality of your test results and should always come from a reputable source. There are several things to consider when choosing a supplier of biological reference materials. First, the supplier’s credentials should be evaluated. The certifications and accreditations that a supplier holds will give an indication of the company’s quality system and provide third-party verification of the supplier’s competence and compliance with global standards.

Traceability is another area that should be taken into consideration when selecting a reference material supplier, especially in the case of reference cultures, because repeated preservation, processing, and subculturing could lead to mutation or characterization aberrations.

A supplier should provide documentation or evidence that a reference culture is traceable to its original source.

Other factors to take into account are the time, labor, and cost savings offered by the supplier. Commercial

reference cultures are available in a variety of different formats. Make sure your supplier offers products that meet your specific needs. Think about the types of testing being performed and the frequency with which they are used. With your list of challenge microorganisms in mind, decide if a qualitative or quantitative microorganism preparation would be beneficial. Compare the ease of use and preparation time for all available options. Customer service and after-sale technical support should also be considered.