Oat raw materials and bakery products - amino acid composition and celiac immunoreactivity

Background. The aim of this study was to compare the biochemical and immunochemical properties of avenins in some special oat raw materials and additionally the possibility of using them as a raw material for the gluten-free bakery products. Materials and methods. The compared oat raw materials were – oat fl akes, commercial oat fl ours (including gluten-free oat fl our) and residual oat fl our, which is by-product of β-glucan preparation. Biochemical characteristic included amino acid compositions and SDS-PAGE profi les of extracted avenins. The immunochemical reactivity with polyclonal anti-gluten and monoclonal anti-gliadin antibodies was evaluated qualitatively and quantitatively by immunoblotting and ELISA methods. Additionally, experimental bakery products made of examined raw materials were assessed according to their suitability for the celiac patients’ diet. Results. The highest protein content was measured in the β-glucan preparation “Betaven“ and gluten-free oat fl our. Proteins of all materials are rich in glutamic and aspartic acid, leucine and arginine. Proportions of amino acids in avenins extracted from most of oat raw materials are similar, excluding gluten-free oat fl our, which has a very low avenin content and proportions of individual amino acids are diff erent. The SDS-PAGE protein pattern consisted of proteins with molecular weight of about 25–35 kDa. Polyclonal anti-gluten antibody recognized all protein fractions of molecular weight higher than 20 kDa. Quantitative ELISA analysis shows that the majority of samples has a gliadin-like protein content within the range of 80–260 mg/kg, excluding gluten-free fl ours and corresponding bakery products. Altogether, β-glucan preparation has extremely high level of gliadin-like proteins. Conclusion. In the examined oat raw materials and foods the contents of immunoreactive amino acid sequences exceeded the limit of 20 mg/kg (considered as gluten-free) except for gluten-free fl ours (oat and the prepared mixture) and the bakery products based on gluten-free fl ours. Unfortunately, the rest of oat raw materials and products cannot be considered gluten-free.