Taste, electronic tongue

The paper describes the different chemical sensors and mathematical methods applied and presents the review of electronic tongue application for quantitative analysis (heavy metals and other impurities in river water, uranium in former mines, metal impurities in exhaust gases, ets) and for classification and taste determination of some beverages (coffee, bear, juice, wines), vegetable oil, milk, etc. [1]. 

A. Legin, A. Rudnitskaya, D. Clapham, B. Seleznev, K. Lord, and Y. Vlasov, Electronic tongue for pharmaceutical analytics quantification of tastes and masking effects. Anal. Bioanal. Chem. 380, 36-45 (2004). 

In order to better describe the utilization purposes, some authors proposed a distinction between electronic tongues and taste sensors the former term should have a wider meaning, embracing all the possible applications, while the latter should exclusively refer to sensory-like evaluations. 

Chen et al. (2008) employed a commercial electronic tongue, based on an array of seven sensors, to classify 80 green tea samples on the basis of their taste grade, which is usually assessed by a panel test. PCA was employed as an explorative tool, while fc-NN and a back propagation artificial neural network (BP-ANN) were used for supervised classification. Both the techniques provide excellent results, achieving 100% prediction ability on a test set composed of 40 samples (one-half of the total number). In cases like this, when a simple technique, such as fc-NN, is able to supply excellent outcomes, the utilization of a complex technique, like BP-ANN, does not appear justified from a practical point of view. 

In a further study, Dias et al. (2009) studied the deployment of a potentiometric electronic tongue based on an array of 36 sensors, for the recognition of the basic taste sensations and for the detection of fraudulent additions of bovine milk to ovine milk. The signals were processed by means of PCA and LDA (see Fig. 2.26), and the classification rules were evaluated by means of cross-validation. The results presented are excellent for fitting but not very satisfactory for prediction. 

An electronic tongue taste evaluation Identification of goat milk adulteration with bovine milk. Sens. Actuators B 136(1), 209-217. 

Ivarsson, P., Kikkawa, Y., Winquist, F., Krantz-Ruelcker, C., Hoejer, N.-E., Hayashi, K., Toko, K., and Lundstroem, I. (2001). A comparison of a voltammetric electronic tongue and a lipid membrane taste sensor with respect to separation of detergent. Chem. Sens. 17 (Suppl. B), 101-103. 

Kantor, D. B., Hitka, G., Fekete, A., and Balia, C. (2008). Electronic tongue for sensing taste changes with apricots during storage. Sens. Actuators B 131(1), 43-47. 

Kayumba, P. C., Huyghebaert, N., Cordelia, C., Ntawukuliryayo, J. D., Vervaet, C., and Remon, J. P. (2007). Quinine sulphate pellets for flexible pediatric drug dosing Formulation development and evaluation of taste-masking efficiency using the electronic tongue. Eur. J. Pharm. Biophurm. 66,460-465. 

Legin, A., Rudinitskaya, A., Vlasov, Y., Di Natale, C., Davide, F., and D Amico, A. (1996). Tasting of beverages using an electronic tongue based on potentiometric sensor array. In "Technical Digest of Eurosensors X, Leuven", pp. 427-430. Elsevier, Amsterdam. 

Rudnitskaya, A., Polshin, E., Kirsanov, D., bammertyn, J., Nicolai, B., Saison, D., Delvaux, F. R., Delvaux, F., and begin, A. (2009a). Instrumental measurement of beer taste attributes using an electronic tongue. Anal. Chim. Acta 646(1-2), 111-118. 

Zheng, J. Y. and Keeney, M. P. (2006). Taste masking analysis in pharmaceutical formulation development using an electronic tongue. Int. J. Pharm. 310(1-2), 118-124. 

The application of this concept to liquid samples is what we already refer to electronic tongue . It entails the use of multidimensional information coming from an array of chemical sensors, mimicking the animal sense of taste. As several possibilities exist on the side of which sensors form the array, the general response shown by the different sensors used is of paramount importance that is, cross-selectivity features are needed in order to profit from the multidimensional aspects of the information [7]. The performance of electronic tongues can be suited not only to qualitative purposes like identification of species and classification of sample varieties, but also to quantitative uses, normally the multidetermination of a set of chemical species, an interesting objective for process control. A more bioinspired trend is the artificial taste [8] in order to perform automated taste perception, especially in the industrial field. 

A. Legin, A. Rudnitskaya, Y. Vlasov, C. Di Natale, F. Davide and A. D Amico, Tasting of beverage using an electronic tongue, Sens. Actuators B, 44 (1997) 291-296. 

A company called Alpha M.O.S. has recently introduced what it calls the world s first commercial electronic tongue, a device used to identify various tastes associated with liquids. Like the Cyranose the electronic tongue must first be... 

In the field of electrochemical sensors for liquids, there is the recent approach known as electronic tongue, which is inspired on the sense of taste. A widely accepted definition of electronic tongue (Holmberg et al. 2004) entails an analytical instrument comprising an array of non-specific, poorly selective, chemical sensors with crosssensitivity to different compounds in a solution, and an appropriate chemometric tool for data processing. 

One scientific area in which neural networks have gained popularity is that of the development of systems inspired on olfactory and taste senses. The electronic nose (Gardner and Bartlett 1999), firstly conceived and applied, has gained recognition in fields like food, aroma or medical diagnosis. The electronic tongue (Vlasov and Legin... 

The widest application of electronic noses and tongues is in the food industry in areas as varied as quality control, process operations, taste studies, and identification of flavor and aroma [3]. All of these areas are discussed in this chapter. In addition, electronic noses are finding use in environmental applications such as the analysis of fuel mixtures, identification of toxic wastes, and the detection of oil leaks [2], Electronic tongues are also now being applied in environmental areas such as analysis of natural waters and detection of heavy metals. Both devices are also being more widely used in clinical and pharmaceutical applications, and several of these will be highlighted. 

An electronic tongue based on dnal shear horizontal surface acoustic wave (SH-SAW) devices was developed to discriminate between the basic tastes of sour, salt, bitter, and sweet [57]. Sixty MHz SH-SAW delay line sensors were fabricated and placed below a miniature PTFE housing containing the test liquid. All the tastes were correctly classified without the need for a selective biological or chemical coating. 

Sehra G., Cole M., and Gardner J. W., Miniature taste sensing system based on dual SH-SAW sensor device An electronic tongue. Sens. Actuators B, 103(1-2), 233, 2004. 

K.-H. Chang, R.L.C. Chen, B.-C. Hsieh, P.-C. Chen, H.-Y. Hsiao, C.-H. Nieh, T.-J. Cheng, A hand-held electronic tongue based on fluorometry for taste assessment of tea. Biosens. Bioelectron. 26, 1507-1513 (2010)... 

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