Authenticity testing of wheat, barley, rye and oats in food and feed market samples by real-time PCR assays

- Authenticity testing of wheat, barley, rye and oats by real-time PCR assays.
- The method allows sensitive and specific detection of each target cereal.
- The applicability of the assay was demonstrated by analyses of commercial foods.
- The assay is a useful tool for monitoring food/feed mislabeling.

This work reports four TaqMan real-time PCR assays for authenticity testing of wheat, barley, rye and oat species in food and feed. The method uses three specific primer/probe systems targeting DNA fragments from the ITS1 region for the detection of wheat, barley and oats, and a fourth primer/probe system targeting the MIPS gene for rye detection. The real-time PCR systems showed high specificity and sensitivity, achieving relative detection limits ranging from 0.00001 to 0.01% in an experimental flour binary mixture model. The developed technique was further applied at the field level to check the labeling of 270 food and pet food products regarding the presence/absence of wheat, barley, rye and oat cereals. The assay allowed the authentication of foods with different labeling schemes, in which the presence of the targeted cereals was either declared, not declared or declared as possible traces.