Species DNA-based identification for detection of processed meat adulteration: is there a role of human short tandem repeats (STRs)?

Abstract

Background: Species identification in the food of animal origin is an essential aspect of its control. Food safety and environmental forensic professionals in various countries are becoming increasingly concerned about the number of serious food offences being carried out by organised criminals. Adulteration in food especially meat is relevant for legal, economic, religious and public health reasons. This study aimed to determine potential adulteration and/or contamination with the donkey, chicken or even human tissues or cells in different marketed red meat products. The products tested were the uncooked beef burger, sausage, kofta and luncheon, manually processed or were of different commercial brands with variable prices, through a PCR-based method. A total of 40 different commercial meat product samples were randomly collected from restaurants, butchers, hypermarkets and local shops. The 12S rRNA region within the mitochondrial DNA was amplified with species-specific primers for identification of two suspected animal species (donkey and chicken) and two nuclear DNA STRs (short tandem repeats) loci, TPOX and D18S51 for excluding human origin of adulteration or contamination. Results: The total beef samples analysed showed 87.5% adulteration and mislabelling with one or more species. They were mostly mixed with chicken meat or their by-products (72.5%) followed by donkey (12.5%) and lastly human (2.5%) that was detected in a manually prepared kofta sample. Conclusion: The used non-human species-specific PCR along with the first reported use of human hypervariable STRs proved valuable and straightforward techniques for species authentication of meat products.