Editor’s note: This is part of a series on food safety costs for businesses. The series is sponsored by CERTUS Food Safety. This piece explores different pathogen testing methods for environmental monitoring.
As food safety regulations have improved and increased within the last decade, a technology boom has given the industry access to more accurate and efficient pathogen testing methods, says Erin Crowley, chief scientific officer for Q Laboratories Inc.
“This has been a welcome development for our industry, but it can be overwhelming to navigate through the different types and their various workflows,” Crowley explains.
While some pathogen testing methods, otherwise known as assays, are designed to give rapid results in the matter of a few hours, others can take days to process. However, depending on what is being sampled (also referred to as an analyte) and what pathogen it is being analysed for, each assay has an important place in an environmental monitoring program.
Crowley outlined four common pathogen testing methods.
“Immunoassays are based on the principles that specific antigens will stimulate very specific (unique) immune responses and that the proteins produced by the immune response – called antibodies – can be used to signal the presence of a target compound in a sample,” explains Crowley.
According to her, there are two types of immunoassays: sandwich and competitive.
Sandwich assays use two antibodies to bind a specific target. One antibody is typically immobilized to a solid support such as nitrocellulose membranes found in lateral flow test strips. This can also be done with a microtiter plate which allows for specific antibody collection, commonly referred to as the ELISA (enzyme linked immunosorbent) test. Each test operates on a visual reporter system, with a lateral flow test signalling pathogen presence with line intensity, explains Crowley. Enzymes used for an ELISA test will catalyze a reaction, changing the solution a different color on the microtiter plate, allowing for an optical density assessment.
Recently a new real time rapid pathogen detection system has been introduced based on Surface Enhanced Raman Spectroscopy (SERS) technology. SERS generates signals that are measured in the near infrared wavelengths where absorption of complex samples such as food is minimal.