A real-time PCR method for the detection and quantification of lupin flour in wheat flour-based matrices

Lupin flour is growingly being used in bakery products, mainly as a soybean protein substitute. The aim of the present work was to detect and quantify the presence of lupin flour in wheat-based foods using a newly set up qPCR system based on SYBR green. Although DNA sequence information for lupin is scarce, it has been possible to design a primer pair highly specific for the target gene and devoid of any primer-dimers amplification capacity. Lupin flour revealed to be a difficult matrix, since large amounts of compounds tend to co-purify with DNA, even adopting well established extraction protocols. Nonetheless, the primers used allowed to reach high PCR efficiencies and did not show any cross-reactivity with DNAs extracted from various plant and animal foods. The sensitivity achieved was 7 pg of lupin DNA, corresponding to a percentage of less than 0.1% of lupin flour in the foods.