Classics in a new perspective: gluten as a special food safety and analytical challenge

In the last couple of decades, the nutritional role and perception of gluten became controversial. In one hand, gluten proteins play a central role in determining the baking quality of wheat and other cereals. On the other hand, hypersensitivity reactions triggered by gluten in susceptible individuals have become subjects of growing interest. Of these gluten-related disorders, with an estimated global prevalence of 1%, the most important one is celiac disease (CD), which is an autoimmune disorder accompanied by villous atrophy. CD can manifest in a wide range of symptoms, its only treatment option is a lifelong gluten-free (GF) diet. To support compliance to this diet, current EU legislation maximizes the gluten-content of products sold with a GF label in 20 mg/kg. It necessitates accurate quantification of gluten in this low concentration range. The method-of-choice for this purpose is the immunoanalytical-based ELISA (enzyme-linked immunosorbent assay). However, validation of different ELISA methods and the comparability of their results and, consequently, the reliability of the data they provide is problematic. The major goal of this paper is to introduce the analytical and protein chemistry issues behind this problem and the efforts to improve the conditions of the methodology. We are also including the special role of oats in the GF diet in an attempt to provide the widest possible overview of the food safety and analytical challenges represented by gluten.