Electronic Noses and Tongues in Wine Industry.

The quality of wines is usually evaluated by a sensory panel formed of trained experts or traditional chemical analysis. Over the last few decades, electronic noses (e-noses) and electronic tongues have been developed to determine the quality of foods and beverages. They consist of arrays of sensors with cross-sensitivity, combined with pattern recognition software, which provide a fingerprint of the samples that can be used to discriminate or classify the samples. This holistic approach is inspired by the method used in mammals to recognize food through their senses. They have been widely applied to the analysis of wines, including quality control, aging control, or the detection of fraudulence, among others. In this paper, the current status of research and development in the field of e-noses and tongues applied to the analysis of wines is reviewed. Their potential applications in the wine industry are described. The review ends with a final comment about expected future developments.

Electroactivity of a starburst hole-transport material in Langmuir-Blodgett films. Solid state effects and intervalence charge transfer.

Here we report on the electroactivity properties of Langmuir-Blodgett (LB) films of the hole-transport molecule 4,4',4''-tris[3-methylphenyl(phenyl)amino] triphenylamine (m-MTDATA). Fairly stable Langmuir films at the air-water interface are accomplished, despite the non-amphiphilic character of the molecule. The reflection-absorption infrared spectroscopy (RAIRS) and Fourier transform infrared (FT-IR) analysis revealed that the molecules arrange with no neat preferential orientation, in agreement with the amorphous glassy nature of this starburst molecule. However, there is a tendency of the molecules to organize in a more planar conformation due to the intermolecular stacking induced by the LB technique. On the other hand, the fundamental electrochemistry (by cyclic voltammetry, CV) of the films is also analyzed. The CV studies of both solution and films reveal that both the solid state and the electrolyte's anions clearly affect the m-MTDATA's electroactivity, exhibiting a unique and broad redox process instead of the two reversible oxidations observed in solution. The oxidization mechanism is discussed. Finally, the spectroelectrochemistry studies evidence that the oxidization of the films leads to new absorption bands, among which the emerging bands in the NIR region ascribed to intervalence charge transfer (IVCT) between the generated aminyl radical cations should be pointed out.