Detection of Gluten-Rich Cereals in Processed Foods with Enhanced Sensitivity by Targeting Mitochondrial DNA Using PCR
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Detection of Gluten-Rich Cereals in Processed Foods with Enhanced Sensitivity by Targeting Mitochondrial DNA Using PCR Nahed Ahmed 1 & Menghsiao Meng 2 Received: 28 June 2018 / Accepted: 10 December 2018 / Published online: 18 December 2018 # Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract Since the correct labeling of foods is the only effective way of protecting celiac disease patients and people allergic to gluten, it is essential to have reliable methods to detect the presence of gluten-containing cereals in foods. DNA-based methods have their merits as complementary approaches to immunochemical assays to detect the possible gluten contamination in processed foodstuff. Nevertheless, insufficient sensitivity is a major drawback for DNA-based analytical methods. Accordingly, DNA markers within mitochondrial DNA were identified in this study as the targets of PCR for the detection of gluten-containing cereals. Primer pairs Mt1F/Mt1R and Mt2F/Mt2R target a unique DNA segment conserved among wheat, barley, rye, and oat, whereas Mt3F/Mt3R targets the other segment that is present only in wheat, barley, and rye. In regard to detection limits, all the three designed primers could detect the presence of 0.2 pg wheat, barley, and rye DNA, 10−5 (10 ppm) of wheat, barley, and rye DNA diluted with soya DNA, or 10−5 (10 ppm) of wheat flour mixed within corn flour. The extremely high copy numbers of mitochondrial genome per cell may explain and justify the astonishing sensitivity of the methods described in this study. The detection of wheat DNA in thermally processed foods by this method is evidence of the suitability and applicability of the method to examine foods with gluten-free labels. Keywords Celiac disease . Gluten-free foods . Wheat allergy . Gliadin . PCR . Molecular diagnosis
Introduction Wheat has a high nutritional value and palatability and can be processed into many foods including, but not limited to, breads, pasta, pizza, and bulgur, as well as drinks such as beer and whiskey. There are more than 40 allergenic proteins in wheat that may trigger human immune responses, some of which cross-react with rye proteins and grass pollens (Blands et al. 1976). While consumption of wheat is typically safe for most people, those sensitive to specific wheat proteins should avoid it in order to remain symptom free. Of the diseases triggered by ingestion of gluten, celiac disease (CD), manifested as a chronic inflammation in the small intestine, raises public attention most. Gliadin of wheat, hordein of barley, and secalin of rye are * Menghsiao Meng [email protected] 1
International Master Program of Agriculture, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 40227, Taiwan
2
Graduate Institute of Biotechnology, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 40227, Taiwan
specifically described as the major stimuli of CD (Taylor 1987). This adverse immune reaction is a lifelong illness, and the cornerstone of treatment of CD mainly relies on the avoidance
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