ARS | Publication request: Complete validation of a unique digestion assay to detect Trichinella larvae in horsemeat demonstrates its reliability for meeting food safety and trade requirements.

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 3, 2007
Publication Date: January 1, 2008
Citation: Forbes, L.B., Hill, D.E., Parker, S., Tessaro, S.V., Gamble, H.R., Gajadhar, A.A. 2008. Complete validation of a unique digestion assay to detect Trichinella larvae in horsemeat demonstrates its reliability for meeting food safety and trade requirements. Journal of Food Protection. 71(3):558-63.

Interpretive Summary: A digestion assay using a magnetic stirrer in an incubation chamber for digestion and a double separatory funnel (DSF) procedure to recover and concentrate larvae from digest fluid were developed to meet stringent QA needs and industry requirements for testing in abattoir laboratories and high sample throughput. The DSF digestion method was incorporated into a diagnostic system that included technical training, proficiency samples, a documented quality assurance system and external audits. The data presented here complete the validation of the DSF digestion method for the detection of Trichinella larvae in horsemeat and demonstrate that this assay is fit for its intended use in food safety and trade. The DSF digestion method offers technical, quality assurance and performance advantages over the SSF digestion method.

Technical Abstract: A tissue digestion assay using a double separatory funnel (DSF) procedure for the detection of Trichinella larvae in horsemeat was validated for application in food safety programs and trade. It consisted of a pepsin-HCl digestion step to release larvae from muscle tissue followed by two sequential sedimentation steps in separatory funnels to recover and concentrate larvae for detection using a stereomicroscope. The assay, with defined critical control points, was conducted within a quality assurance system compliant with ISO 17025 guidelines. Under these conditions, the DSF digestion assay performed significantly better than the SSF method in the range of ' 2 lpg, both in terms of positive tissues identified and larval recovery. The data demonstrate that the DSF digestion assay is reliable and efficient. The DSF is the only validated digestion assay for trichinellosis demonstrating consistency and effectiveness at critical levels of sensitivity.