Droplet digital PCR for detection of allergenic peanut in food ingredients

Background

Peanut is regulated as a major food allergen in the United States. Food products containing peanut must be labeled according to the Food, Drug, and Cosmetics (FD&C) Act, and accurate labeling requires effective detection methods. Polymerase chain reaction (PCR)-based methods are highly sensitive, specific, and robust for this purpose. Digital PCR is the latest generation of PCR technology and offers potential advantages over more established PCR techniques, but very few studies report the evaluation of digital PCR for use in food allergen detection.

Results

In this work, a multiplex digital PCR assay was evaluated for the detection of peanut in food ingredients at levels ranging from 0.1 mg/kg (ppm) to 10⁶ mg/kg (100% peanut), and it was compared to a real-time PCR assay. Both digital and real-time PCR detected peanut effectively at all levels in all food ingredients. Digital PCR had limits of detection (LOD) at 0.1 mg/kg for all three targets and limits of quantification (LOQ) at 1–10 mg/kg depending on the target. Real-time PCR had LOD at 0.1–10 mg/kg depending on the target, and LOQ at 100 mg/kg.

Conclusions

Digital PCR was both more precise and more sensitive than real-time PCR for detection of peanut spiked into food ingredients. While more testing is needed to determine the relative effects of complex food matrices and processing, these early results show that digital PCR is an innovative method that can help ensure chemical food safety through sensitive, precise detection of DNA from allergenic foods such as peanut.