Voltammetric electronic tongue and support vector machines for identification of selected features in Mexican coffee.

Rocio Domínguez,Roberto Muñoz,Juan Gutiérrez,Laura Moreno-Barón

doi:10.3390/s140917770

Abstract

This paper describes a new method based on a voltammetric electronic tongue (ET) for the recognition of distinctive features in coffee samples. An ET was directly applied to different samples from the main Mexican coffee regions without any pretreatment before the analysis. The resulting electrochemical information was modeled with two different mathematical tools, namely Linear Discriminant Analysis (LDA) and Support Vector Machines (SVM). Growing conditions (i.e., organic or non-organic practices and altitude of crops) were considered for a first classification. LDA results showed an average discrimination rate of 88% ± 6.53% while SVM successfully accomplished an overall accuracy of 96.4% ± 3.50% for the same task. A second classification based on geographical origin of samples was carried out. Results showed an overall accuracy of 87.5% ± 7.79% for LDA and a superior performance of 97.5% ± 3.22% for SVM. Given the complexity of coffee samples, the high accuracy percentages achieved by ET coupled with SVM in both classification problems suggested a potential applicability of ET in the assessment of selected coffee features with a simpler and faster methodology along with a null sample pretreatment. In addition, the proposed method can be applied to authentication assessment while improving cost, time and accuracy of the general procedure.

Highlights

According to the International Coffee Organization (ICO), in the 2012 productive year, Mexico occupied the eighth position among the world coffee producers [1]
Catalytic oxidative signals seem to be originated from the metal nanopaticle modified sensors, which may be due to a catalytic oxidation of saccharides and/or polyphenols on the sensor surface
Samples from the principal Mexican coffee regions and samples with designation of origin (DO) were included in the data set

Summary

Introduction

According to the International Coffee Organization (ICO), in the 2012 productive year, Mexico occupied the eighth position among the world coffee producers [1]. Mexican production is supported by approximately 15 regions of coffee growing, distinguished by geographical location, local microclimate and the particular cultivation procedures followed in each zone. To ensure coffee quality for final consumers, the Mexican government established different regulations for evaluation in accordance to international standards. In this sense, and given the importance of geographical location, Veracruz and Chiapas own a protected designation of origin (DO) [2,3]. To ensure high standards in the coffee industry, extensive research to study key qualities in coffee has been lead. A considerable number of studies have been conducted to characterize the flavor [5], aroma [6,7], as well as to identify the chemical composition of coffee beans [8] and authenticity [9]

Objectives

Results

Conclusion