Descrição
Celiac disease is an autoimmune-mediated disorder triggered in genetically susceptible
individuals by the ingestion of some gluten proteins, namely gliadins. To prevent
inadvertent gluten consumption, the Commission Regulation (EC) Nº41/2009 will
implement labelling foods as “gluten-free” or “low-gluten content”[1].
The feasibility of an all-solid-state potentiometric electronic tongue to detect the
contamination of “gluten-free” foodstuffs with gliadins was evaluated. The device was
constituted by 36 cross-sensibility lipo/polymeric membranes and its performance was
assessed using food ethanolic extracts (Figure 1).
A semi-quantitative linear discriminant (LDA) model was established based on the
signal patterns of 11 polymeric membranes. The model was able to distinguish between
“Gluten-free” extracts (<10 ppm gliadins), “Low-Gluten content” extracts (20-50 ppm
gliadins) and “Gluten-containing” extracts (>50 ppm gliadins), with sensibilities of
100% and 77% for the original grouped cases and “leaving one-out” cross-validation,
respectively (Figure 2). The device sensitivity was towards 1-2 ppm.
The device was also applied to discriminate between “gluten-free” and “glutencontaining”
foodstuffs (flours, baby milked flours, breads, cookies and breakfast
cereals), being the label information checked by HPLC-DAD analysis. In this case, the
LDA was based on the signals of only 4 polymeric membranes. The model allowed to
classify correctly 89% and 84%, for the original grouped cases and “leaving one-out”
cross-validation procedures, respectively, which is very satisfactory taking in account
the higher complexity due to the food matrix effect. Furthermore, only one of the
“Gluten-containing” foodstuffs (a bread sample) was misclassified by the model as
“Gluten-free”. This misclassification could be tentatively due to an additional difficulty
in the gliadins extraction from bread, which is a more processed food matrix.
Finally, the work carried out showed that the E-tongue device could be used in practice
as a fast and economic preliminary tool to evaluate, in a real time basis, the possible
gluten contaminations of “Gluten-free” foodstuffs.
; Dias, Luís G. 
