Identification of monofloral honey using voltammetric electronic tongue Kamalika Tiwari a , Bipan Tudu b,⇑ , Rajib Bandyopadhyay b , Anutosh Chatterjee b a Department of Electronics and Instrumentation Engineering, Dr. B.C. Roy Engineering College, Durgapur 713 206, India b Department of Instrumentation and Electronics Engineering, Jadavpur University, Kolkata 700 098, India article info Article history: Received 21 July 2012 Received in revised form 26 February 2013 Accepted 27 February 2013 Available online 14 March 2013 Keywords: Electronic tongue Cyclic voltammetry Monofloral honey Principal component analysis (PCA) Linear discriminant analysis (LDA) Neural networks abstract Quality assessment of honey is often related to its floral origin which is a complex task to evaluate. Tra- ditional technique of floral assessment is made by melissopalynological method. However, this method is quite time consuming and also often operator dependent. Thus, the fallout is a large range of error in interpretation of the result and hence there is considerable demand for instrumental methods to assess the identification of pollen in honey. In this pursuit, an electronic tongue based on cyclic voltammetry is developed to discriminate honey samples based on their floral types and is described in this paper. The technique has been investigated using platinum as the working electrode and the resultant current from the potentiostat has been considered for data analysis. The use of principal component analysis (PCA) and linear discriminate analysis (LDA) proves to be useful in clustering honey samples. Finally, classification performances are investigated using back-propagation multilayer perceptron (BP-MLP) and radial basis function (RBF) neural network models for identification of different floral origin of honey. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Honey is a natural sweet substance and is produced by honey- bees from the nectar of blossoms, as well as from honeydew (Co- dex Alimentarius, 1981). Pollen identification is an essential tool in the analysis of honey and the information about the floral origin has vital commercial value since honey from particular plants com- mands high market price. Pollen identification and quantification help to determine nectar types and to identify the geographical ori- gin of the honey. Of late, the international honey market is getting stringent towards quality and hence honey producers need to indi- cate botanical origin of the honey. Pollen composition of honey re- veals vegetation, climate and geographical location along with the flora of that particular region. Thus commercialization of honey completely depends upon color, flavor and texture which is depen- dent on the particular pollen type. Traditionally, the melossopaly- nology technique has been used for the determination of floral origin. This technique is based on the identification of pollen by microscopic inspection. However, there are some drawbacks of the technique (Anklam, 1998). The amount of pollen can vary from season to season and some of the pollens may be collected from plants that are not the sources of honey. Also, the bees can take pollen without collecting nectar and using microscopic inspection, the variability cannot be estimated. Another major limitation of this method is fraud addition of pollen for authenticity. Few re- ports present the characterization of honey by its chemical and sensory characteristics (Anklam, 1998; Anupama et al., 2003; Cor- bella et al., 2005). Various other instrumental methods such as high performance liquid chromatography (HPLC), gas chromatog- raphy mass-spectrometry (GC–MS), ion-chromatography (IC) and mid-infrared spectroscopy. have been used to determine the botanical origins and to verify the authenticity of the honey sam- ples. All the analytical methods are time consuming, involve com- plex sample preparation and require skilled person. For this reason, many researchers have attempted to identify the type of honey by electrochemical method of analysis i.e. electronic tongue (Wei et al. 2009, 2011; Major et al., 2011). The various measurement principles that can be used for complex liquid media analysis are potentiometry, conductometry, spectrophotometery, voltammetry, etc. Among these, voltammetry has several advantages and is cho- sen in our study. Extensive study has been conducted on voltam- metric electronic tongue for the purpose of estimation of quality of black tea (Bhattacharyya et al., 2012), ageing process of juice and freshness of milk (Winquist et al., 1997), distilled spirits (Tian et al., 2006). Voltammetry technique entails numerous advantages like high sensitivity, versatility, simplicity, robustness and good signal to noise ratio (Winquist, 2008). In voltammetry, a potential is applied to the working electrode and the information is obtained from the transient current as the redox active species are reduced or oxidized on the electrode surface. Also voltammetry has numer- ous techniques like cyclic, stripping and pulse voltammetry, alter- nating current voltammetry, etc. Voltammetric measurements provide choice of potential and type of working electrode and in 0260-8774/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jfoodeng.2013.02.023 ⇑ Corresponding author. Address: Department of Instrumentation and Engineer- ing, Jadavpur University, Salt Lake Campus, Block LB, Sector III, Plot 8, Salt Lake, Kolkata 700 098, India. Tel.: +91 33 23352587; fax: +91 33 23357254. E-mail address: bt@iee.jusl.ac.in (B. Tudu). Journal of Food Engineering 117 (2013) 205–210 Contents lists available at SciVerse ScienceDirect Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng