A hybrid electronic tongue for direct classification of baby liquid foods with or without gluten

Abstract

People suffering from celiac disease are gluten intolerant and inadvertent ingestion of gluten proteins must be avoided. Several techniques have been proposed to detect/quantify gluten proteins in foodstuffs: immunochemical methods, mass tandem spectrometry and polymerase chain reaction as well as gluten sensors [1]. Recently, a potentiometric electronic tongue (ET) with lipo/polymeric membranes has been used to detect gliadins, which are gluten proteins, in foodstuffs [2]. However, the use of these techniques requires the previous extraction of gluten proteins. This step can be a possible drawback since it is not possible to guarantee that the extraction has a 100% yield since the protein types overlap in solubility and extractability [3]. In this work, the feasibility of a hybrid multi-sensor ET, which combines repeated cross-sensitivity and ion selective sensors (Fig. 1), to discriminate gluten-free and gluten-containing liquid baby foods has been evaluated. The device was constructed using a screen- printed technique and directly applied in the liquid infant food samples. No extraction or dilution/dissolution step was required. In total, 5 “gluten-free” and 10 “gluten- containing” liquid baby foods of different flavors were purchased at local supermarkets and analyzed. The preliminary results obtained from the principal component analysis (Fig. 2) show that the signals profiles recorded by the hybrid ET possessed valuable information allowing grouping the samples in mainly two groups. In fact, linear discriminant analysis allowed the correct classification of 95% of the samples (leave- one-out cross-validation process) being only one baby liquid food containing gluten misclassified as gluten-free. Although further studies are needed, the satisfactory preliminary results described here presumably demonstrate the ability of the hybrid ET to be used as a rapid and disposable practical tool for quality control of liquid foods for babies suffering from gluten intolerance.