A Digital PCR Assay to Quantify the Percentages of Hulled vs. Hulless Wheat in Flours and Flour-Based Products

SIMPLE SUMMARY: The agri-food market is currently showing interest in hulled wheat-based products, in particular emmer and spelt. These wheats were rediscovered as ingredients for both traditional and innovative food products. Since hulled wheats’ commodity value is higher than common and durum wheat, it is useful to have an analytical system that allows to control and quantify the actual presence of einkorn, emmer and spelt and, therefore, check the authenticity of derived products. With this aim, we developed an analytical assay based on digitalPCR, which has been able to discriminate between hulled (i.e., einkorn, emmer and spelt) and common or durum wheats and to give a quantification. The assay can be used along production chains, from raw materials to final food products. ABSTRACT: Several food products, made from hulled wheats, are now offered by the market, ranging from grains and pasta to flour and bakery products. The possibility of verifying the authenticity of wheat species used at any point in the production chain is relevant, in defense of both producers and consumers. A chip digital PCR assay has been developed to detect and quantify percentages of hulless (i.e., common and durum wheat) and hulled (i.e., einkorn, emmer and spelt) wheats in grains, flours and food products. The assay has been designed on a polymorphism in the miRNA172 target site of the AP2-5 transcription factor localized on chromosome 5A and involved in wheat spike morphogenesis and grain threshability. The assay has been evaluated even in a real-time PCR system to assess its applicability and to compare the analytical costs between dPCR and real-time PCR approaches.