Discrimination of civet and non-civet coffee by linear discriminant analysis (LDA), partial least squares (PLS-DA), and orthogonal projection to latent structures (OPLS-DA)

One of the issues faced by coffee traders and consumers is the widespread availability of adulterated civet coffee (kopi luwak) in the market. To address this problem, the industry needs a way to discriminate between civet and non-civet coffee. Metabolomics data consisting of 24 coffee beans were su...

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Bibliographic Details
Main Authors: Datinginoo, Madelene R., Losanes, Christine Angelica L.
Format: text
Language:English
Published: Animo Repository 2015
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Online Access:https://animorepository.dlsu.edu.ph/etd_bachelors/8534
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Institution: De La Salle University
Language: English
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Summary:One of the issues faced by coffee traders and consumers is the widespread availability of adulterated civet coffee (kopi luwak) in the market. To address this problem, the industry needs a way to discriminate between civet and non-civet coffee. Metabolomics data consisting of 24 coffee beans were subjected to linear discriminant analysis (LDA), partial least squares discriminant analysis (PLS-DA), and orthogonal projection to latent structures discriminant analysis (OPLS-DA). LDA identified isonicotinic acid, 3-hydroxybenzoic acid, arbutin, and propane-1,3-diol NIST as discriminant markers. On the other hand, PLS-DA described three factors highly represented by: (1) sugars and organic acids (2) aroma acids and (3) taste acids as responsible for successful class separation. Lastly, OPLS-DA showed that isonicotinic acid, 5-aminovaleric acid, beta-glutamic acid, pentitol, and urea were the most significant in discriminating the data. All the fitted models yielded 0 misclassification rates. The LDA model exhibited an R2 of 88.56%, while the OPLS-DA and PLS-DA models demonstrated R2Y of 87.9%. Unlike LDA, PLS-DA is not governed by a set of assumptions. The PLS-DA model was also evaluated with a higher Q2 (62.6%) than that of the OPLS-DA model Q2 (51.5%). Hence, among the three discriminant analyses, PLS-DA is the recommended analysis tool for discriminating between civet and non-civet coffee samples.