Detection of wheat adulteration of spelt flour and products by PCR

To date, no general method to detect wheat [Triticum aestivum vulgare (Vill .) Mackey] adulteration of spelt [T. aestivum spelta (L) Thell.] exists. Ex ploiting a published allelic difference in gamma -gliadin gene GAG56D. we d eveloped and evaluated three PCR-based methods to determine the proportion of wheat in spelt flour and products. A sensitive wheat-specific PCR system was designed. Moreover, a heterologous internal standard was constructed f or quantitative competitive (QC-)PCR. The standard was arbitrarily calibrat ed to 5% wheat DNA in spelt DNA. A PCR-RFLP system consisting of a GAG56D-s pecific PCR system with subsequent restriction was used to estimate the rel ative proportions of wheat and spelt in DNA mixtures. The three methods wer e successfully applied to seven commercial spelt samples and one self-produ ced bread. Five and three of the seven samples were found to contain more t han 5% and 10% wheat, respectively. One sample appeared to contain no spelt at all. Analyzing the bread crumb with PCR-RFLP, we were able to estimate the wheat content of the flour which was used to produce the bread and thus demonstrated the applicability of PCR-RFLP to quantify processed products.