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Sensors 2018, 18(1), 95; https://doi.org/10.3390/s18010095

Identification of Coffee Varieties Using Laser-Induced Breakdown Spectroscopy and Chemometrics

1,2
,
1,2
,
1,2,* and 1,2
1
College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
2
Key Laboratory of Spectroscopy Sensing, Ministry of Agriculture, Hangzhou 310058, China
*
Author to whom correspondence should be addressed.
Received: 7 November 2017 / Revised: 13 December 2017 / Accepted: 27 December 2017 / Published: 31 December 2017
(This article belongs to the Special Issue Spectroscopy Based Sensors)
View Full-Text   |   Download PDF [2438 KB, uploaded 31 December 2017]   |  

Abstract

We linked coffee quality to its different varieties. This is of interest because the identification of coffee varieties should help coffee trading and consumption. Laser-induced breakdown spectroscopy (LIBS) combined with chemometric methods was used to identify coffee varieties. Wavelet transform (WT) was used to reduce LIBS spectra noise. Partial least squares-discriminant analysis (PLS-DA), radial basis function neural network (RBFNN), and support vector machine (SVM) were used to build classification models. Loadings of principal component analysis (PCA) were used to select the spectral variables contributing most to the identification of coffee varieties. Twenty wavelength variables corresponding to C I, Mg I, Mg II, Al II, CN, H, Ca II, Fe I, K I, Na I, N I, and O I were selected. PLS-DA, RBFNN, and SVM models on selected wavelength variables showed acceptable results. SVM and RBFNN models performed better with a classification accuracy of over 80% in the prediction set, for both full spectra and the selected variables. The overall results indicated that it was feasible to use LIBS and chemometric methods to identify coffee varieties. For further studies, more samples are needed to produce robust classification models, research should be conducted on which methods to use to select spectral peaks that correspond to the elements contributing most to identification, and the methods for acquiring stable spectra should also be studied. View Full-Text
Keywords: coffee varieties; laser-induced breakdown spectroscopy; discrimination; chemometrics; wavelength selection coffee varieties; laser-induced breakdown spectroscopy; discrimination; chemometrics; wavelength selection
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Zhang, C.; Shen, T.; Liu, F.; He, Y. Identification of Coffee Varieties Using Laser-Induced Breakdown Spectroscopy and Chemometrics. Sensors 2018, 18, 95.

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