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NIRS and Aquaphotomics Trace Robusta-to-Arabica Ratio in Liquid Coffee Blends

Department of Measurements and Process Control, Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences, 14-16. Somlói Street, H-1118 Budapest, Hungary
Department of Dietetics and Nutrition Faculty of Health Sciences, Semmelweis University, 17. Vas Street, H-1088 Budapest, Hungary
Department of Food Science and Technology, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi 00233, Ghana
Author to whom correspondence should be addressed.
Academic Editor: Stefano Materazzi
Molecules 2022, 27(2), 388;
Received: 17 December 2021 / Revised: 4 January 2022 / Accepted: 5 January 2022 / Published: 8 January 2022
(This article belongs to the Special Issue Aquaphotomics - Exploring Water Molecular Systems in Nature)
Coffee is both a vastly consumed beverage and a chemically complex matrix. For a long time, an arduous chemical analysis was necessary to resolve coffee authentication issues. Despite their demonstrated efficacy, such techniques tend to rely on reference methods or resort to elaborate extraction steps. Near infrared spectroscopy (NIRS) and the aquaphotomics approach, on the other hand, reportedly offer a rapid, reliable, and holistic compositional overview of varying analytes but with little focus on low concentration mixtures of Robusta-to-Arabica coffee. Our study aimed for a comparative assessment of ground coffee adulteration using NIRS and liquid coffee adulteration using the aquaphotomics approach. The aim was to demonstrate the potential of monitoring ground and liquid coffee quality as they are commercially the most available coffee forms. Chemometrics spectra analysis proved capable of distinguishing between the studied samples and efficiently estimating the added Robusta concentrations. An accuracy of 100% was obtained for the varietal discrimination of pure Arabica and Robusta, both in ground and liquid form. Robusta-to-Arabica ratio was predicted with R2CV values of 0.99 and 0.9 in ground and liquid form respectively. Aquagrams results accentuated the peculiarities of the two coffee varieties and their respective blends by designating different water conformations depending on the coffee variety and assigning a particular water absorption spectral pattern (WASP) depending on the blending ratio. Marked spectral features attributed to high hydrogen bonded water characterized Arabica-rich coffee, while those with the higher Robusta content showed an abundance of free water structures. Collectively, the obtained results ascertain the adequacy of NIRS and aquaphotomics as promising alternative tools for the authentication of liquid coffee that can correlate the water-related fingerprint to the Robusta-to-Arabica ratio. View Full-Text
Keywords: coffee; NIRS; aquagrams; chemometrics; authentication; PCA; PCA-LDA; PLSR coffee; NIRS; aquagrams; chemometrics; authentication; PCA; PCA-LDA; PLSR
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MDPI and ACS Style

Aouadi, B.; Vitalis, F.; Bodor, Z.; Zinia Zaukuu, J.-L.; Kertesz, I.; Kovacs, Z. NIRS and Aquaphotomics Trace Robusta-to-Arabica Ratio in Liquid Coffee Blends. Molecules 2022, 27, 388.

AMA Style

Aouadi B, Vitalis F, Bodor Z, Zinia Zaukuu J-L, Kertesz I, Kovacs Z. NIRS and Aquaphotomics Trace Robusta-to-Arabica Ratio in Liquid Coffee Blends. Molecules. 2022; 27(2):388.

Chicago/Turabian Style

Aouadi, Balkis, Flora Vitalis, Zsanett Bodor, John-Lewis Zinia Zaukuu, Istvan Kertesz, and Zoltan Kovacs. 2022. "NIRS and Aquaphotomics Trace Robusta-to-Arabica Ratio in Liquid Coffee Blends" Molecules 27, no. 2: 388.

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