Does my burger contain horse meat ?

Sarah Parker


Supervised by Liam Turner; Moderated by Kirill Sidorov

Meat adulteration, meat fraud, meat substitution has always been a problem, but it has been highlighted in recent years by the ‘Horse meat drama’. As such, part of the testing requirements for food samples is the determination of each meat species contribution within the total meat content (e.g. is my lamb curry actually ‘lamb’, does my burger contain ‘horse’ meat etc). Two of the main approaches to determine meat species are DNA sequencing and quantitative polymerase chain reaction (qPCR). DNA sequencing can be used to ‘identify’ all the contributing species (DNA) from within the sample under test but this approach is time consuming and costly. Also, when taking into to consideration that the substituted meat needs to be ‘available’ (e.g the presence of polar bear meat in your lasagna is unlikely !) a more targeted approach of testing using qPCR is more commonly utilized. Thus, individual qPCR assays are undertaken for each species (e.g. Horse, Beef, Pork, Lamb, Chicken, Turkey, Goat etc) and the obtained result is ‘compared’ with an Universal assay (‘anything with legs’) to calculate the total contribution from each of the tested species. The data obtained from the qPCR machine is usually a complex sample/species matrix – each ‘PCR plate’ (run) has 96 wells (thus up to 96 raw data points per plate) and testing a batch of samples will result in a combination of the following: •Multiple PCR runs (plates) per batch of samples •One or many species per plate (run) •Multiple samples within each batch – each sample will have varying testing requirements (check for 2/3/../7/8/? Species) •Single, duplicate or triplicate wells for each sample. •Replicates extractions of the original sample. •QC standards for each species (e.g. extraction blank, extraction standard, PCR blank, PCR Standard, etc etc) Once all the qPCR runs have been completed – the data for each run needs to be stitched back together so that every sample has a percentage contribution result for each species tested (note: ‘batch specific’ results with up to 10 PCR plates per batch). Currently we use an extensive set of excel workbooks/QC charts to process the raw data from the qPCR machine, compare/check the extraction & PCR controls fall within QC criteria and finally end up with the percentage of each species contribution for the client report.

The project will cover the creation of an ‘application’ that would 'automate' this process & with the added value of reducing/eliminating transcription errors. The steps involved would be processing the raw data through to creating two exports, one for the Public Analyst and a second which contains the results in a format than be imported straight into the Laboratory Information Management System (LIMS).

Final Report (11/09/2023) [Zip Archive]

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