Mini-electronic Tongue Used to Discriminate between Coffee Samples of Different Geographical Origin
Published at : 21 Apr 2020
Volume : IJtech
Vol 11, No 2 (2020)
DOI : https://doi.org/10.14716/ijtech.v11i2.3225
Arrieta, A.A., Nuñez, Y.E., Mendoza, J.M., 2020. Mini-electronic Tongue Used to Discriminate between Coffee Samples of Different Geographical Origin. International Journal of Technology. Volume 11(2), pp. 288-298
| A.A. Arrieta | Department of Biology and Chemistry – University of Sucre, Carrera 28 # 5-267 Barrio Puerta Roja, P.C 700008, Sincelejo, Colombia |
| Y.E. Nuñez | Universidade Tecnológica Federal do Paraná, ua Dep. Heitor Alencar Furtado, 5000 – Campo Comprido, Curitiba – PR, 81280-340, Brazil |
| J.M. Mendoza | Department of Mechanical Engineering, University of Cordoba, Carrera 6 No. 76-103, C.P. 14014, Montería, Colombia |
This paper presents a
mini-electronic tongue that used a polymeric sensor array made from polypyrrole
to discriminate between coffee samples of different geographical origin. The
electronic tongue consisted of a system with a voltammetric sensor array
coupled to a multichannel measuring device (multi-potentiostat) that was
controlled by a multivariable data collection and processing application. The
samples analyzed comprised two types: a series of substances with different
chemical and taste properties and a group of samples of coffee of the Arabica
variety harvested from different geographical areas of Colombia. The electronic
tongue demonstrated the ability to discriminate between solutions with
different gustatory properties. In the analysis of the coffee samples, each
sensor showed a particular voltammetric response to each of the samples
studied. A principal component analysis was undertaken, which resulted in clear
discrimination between each of the coffee samples. It was concluded that the
portable electronic tongue equipped with polymer sensors is able to
discriminate between samples of coffee of different geographical origin.
Coffee; Electronic tongue; Electrochemistry; Polypyrrole; Sensors
Coffee is undoubtedly one of the most popular drinks around the world,
and for this reason, it has been widely studied (Mahachandra
et al., 2017; Iswanto et al., 2019; Haryuni et al., 2019). Its
commercialization occupies a very important place in the economies of countries
like Colombia, Brazil, and Vietnam, among others. In Colombia, several dozen
municipalities produce coffee; however, each producing area generates grains
with different organoleptic characteristics that differentiate them from each
other and from the varieties of coffee grown in other countries (Sanja et al., 2008; Athanassiou et al., 2016; Mehari et
al., 2016; Thorburn-Burns et al., 2017).
Accordingly, the concept of denomination of origin was generated, which
guarantees the quality and provenance of a product. In Colombia, there are more
than 10 denominations of origin, and each offers a coffee with particular
features and certain quality
These sensorial methods aim to evaluate the sensations produced by a particular coffee as a whole. Sensory analysis can be defined as the experimentation and analysis of the global characteristics of a product through the senses; such features are known as organoleptic characteristics. The senses of smell and taste are known as chemical biosensors because they respond directly to stimuli produced by molecules that cause nervous excitation. Thus, the olfactory and gustative systems serve as inspiration for the development of devices seeking in some way to mimic their ability to classify and discriminate between complex substances. These systems are known as electronic noses and electronic tongues (Parra et al., 2006; Di Rosa et al., 2017).
Electronic tongues are used mainly to analyze substances in the liquid phase and have been applied successfully to test numerous beverages (Parra et al., 2006; Chen et al., 2008; Arrieta et al., 2010; Arrieta and Tarazona, 2014; Fuentes et al., 2017). An electronic tongue device consists of three parts: a sensor array that is responsible for sensing analytical samples, a multichannel electronic system, and a computer system equipped with multivariate statistical analysis tools. Although electronic tongues have been used in numerous applications, their use in the discrimination and classification of coffee has rarely been reported (Buratti et al., 2014; Lopetcharat et al., 2016). Indeed, to the best of our knowledge, there are no studies in which coffee samples have been classified according to their geographical origin using this new technology. Accordingly, this work explores the potential of a voltammetric electronic tongue to discriminate between coffee samples with organoleptic characteristics, which is important when validating the origin of these types of products.
The
aim of this work was to evaluate the application of a mini-electronic tongue to
discriminate between coffee samples from different geographic regions. The
device comprised a polymeric sensor array made from polypyrrole (PPy) modified
with different counterions, a multichannel electronic device based on
programmable system-on-chip (PSoC) technology coupled to a computer system with
multivariable analysis tools.
In
this study, an electronic tongue device with PSoC technology that was
integrated with a polymeric sensor array with PPy modified using different
counterions was shown to be capable of discriminating between simple substances
with distinct chemistry and gustatory properties: NaCl (saltiness), sucrose
(sweetness), caffeine (bitterness), citric acid (sourness), and vanillin
(bitterness). Each sensor presented a different signal for each analyzed
sample, demonstrating cross-selectivity, and this allowed the sensor to
generate a fingerprint of the sample. This information was then extracted
through principal component analysis, enabling the sensor to discriminate
between each substance. The mini-electronic tongue device was able to
discriminate between samples of coffee harvested from different geographical
areas (although the samples were of the same varieties and processed
similarly). In this study, it was concluded that the information provided by
the sensor array could collect and supply sufficient information to
discriminate between the coffee samples from different origin denominations.
Additionally, the results showed that this discrimination was related to the
geographical similarities of the areas of origin of the samples. This type of
study opens the possibility of applying the electronic tongue not only in the
coffee sector, but also for use with other products where the designations of
origin are synonymous with quality and have a significant impact on the price
of, and market for, the products.
The authors acknowledge the financial support
provided by the Administrative Department of Science, Technology and Innovation
(Colciencias) and the University of Sucre.
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