OFFGEL electrophoresis and tandem mass spectrometry approach compared with DNA-based PCR method for authentication of meat species from raw and cooked ground meat mixtures containing cattle meat, water buffalo meat and sheep meat

- OFFGEL electrophoresis enriches low-abundance proteins in meat species identification.
- Peptides from myosin light chain isoforms provide species-specific information.
- Proteomic approach detects as low as 0.5% contaminating buffalo meat in sheep meat.
- Label free quantitation method for relative quantification and meat authentication.
- Mitochondrial D loop gene is species-specific and sensitive for meat authentication.

The present study compared the accuracy of an OFFGEL electrophoresis and tandem mass spectrometry-based proteomic approach with a DNA-based method for meat species identification from raw and cooked ground meat mixes containing cattle, water buffalo and sheep meat. The proteomic approach involved the separation of myofibrillar proteins using OFFGEL electrophoresis, SDS-PAGE and protein identification by MALDI-TOF MS. Species-specific peptides derived from myosin light chain-1 and 2 were identified for authenticating buffalo meat spiked at a minimum 0.5% level in sheep meat with high confidence. Relative quantification of buffalo meat mixed with sheep meat was done by quantitative label-free mass spectrometry using UPLC-QTOF and PLGS search engine to substantiate the confidence level of the data. In the DNA-based method, PCR amplification of mitochondrial D loop gene using species specific primers found 226 bp and 126 bp product amplicons for buffalo and cattle meat, respectively. The method was efficient in detecting a minimum of 0.5% and 1.0% when buffalo meat was spiked with cattle meat in raw and cooked meat mixes.