Detection of Contaminants in Food: Presence of Animal Species
Microchem Cape Town molecular diagnostic department can offer the sensitive detection of contaminants of meat for the following range of animal species:
*Where detection of other species is required, kindly consult the laboratory and we can investigate.
What does the result determine?
The result is able to determine the presence or absence of specific animal DNA in a food sample. This method allows for the approximate quantification of the target DNA. The analysis can indicate the presence of trace amounts, low amounts or high amounts of the target DNA detected. It is best suited to detect contamination or adulteration of food products with a specific species of meat. A detection level of >1% horse DNA in a beef product could indicate gross contamination or deliberate substitution of beef with horse meat. The method is very sensitive and allows for detection levels as low as 0.1% presence.
The precision of the PCR method is affected when high amounts of target DNA is present. For this reason absolute quantification of the purity of a food sample cannot be precisely calculated using the PCR, and only an estimated level can be reported. It is therefore not suited to declare a product as pure e.g. ‘100% pure beef’, but can report approximate high levels of DNA detected.
How does the method work?
The method is based on the PCR (Polymerase Chain Reaction) amplification of a unique label present in the mitochondrial genome of the species under investigation. This allows for the detection of all strains of interest, while excluding detection of other closely related species. Since there are multiple copies of each mitochondrial genome within each cell, the detection sensitivity is increased to detect as low as a 0.1% presence.
PCR amplification is detected by means of a probe which is degraded during the PCR, releasing fluorescence. The fluorescence is used to both detect, and quantify the amount of DNA present in the sample. The greater the amount of DNA present, the more fluorescence will be emitted.
Where the presence of a possible contaminant is found, the efficiency of the DNA extraction process is verified to confirm the quantity of total animal species DNA. In this way, trace amounts of DNA are not incorrectly reported as deliberate adulteration or contamination.
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