Detection of adulterated coffee by fourier-transform infrared (FTIR) spectroscopy associated with sensory analysis




Because of its huge economic value, coffee has been the target of adulteration worldwide. Given the successful application of spectroscopic methods in detecting adulterants, this study aimed to employ attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) to detect adulterants in roasted coffee samples and compare the results with that of sensory analysis. In this study, twelve coffee samples were intentionally adulterated with varying concentrations, i.e., 10%, 30%, and 50%, of corn, beans, sawdust, and coffee husk. These adulterated samples were compared with one unadulterated coffee sample and four roasted and ground commercially available coffee samples; spectral readings of caffeine and chlorogenic acid (CGA) standards were performed for reference. The sensory analysis was performed by 17 tasters who were trained by a Q-grader. The infrared (IR) spectra 
(FTIR) data were processed by multiplicative signal correction (MSC) and subjected to a principal component analysis (PCA), along with the results of the sensory analysis. The combination of sensory analysis and IR spectrum allowed to differentiate samples of adulterated coffee and unadulterated coffee by PCA, with an explanation of 79% variance. The results demonstrated that the wavenumbers associated with CGA and caffeine contribute significantly in distinguishing adulterated coffee samples.
Key words: Adulterants; coffee quality; chemometric; sensory analysis.

Author Biography

Nelson Gutierrez Guzmán, Universidad Surcolombiana - Cesurcafe. Neiva, Colombia.

Postdoctorado Universidad Politecnica de Valencia
Tecnología de Alimentos
Febrerode2012 - Juniode 2012
Analisis y control de calidad en pescado

Doctorado Universidad Politecnica de Valencia
Doctorado tecnologia de alimentos
Enerode2002 - Noviembrede 2008
Identificación y priorización de factores críticos para implantar buenas prácticas agrícolas en productores de café y frutas en el departamento del Huila en Colombia

Maestría/Magister Universidad Politecnica de Valencia
Master ciencia ingenieria de alimentos
Enerode2002 - de 2002

Pregrado/Universitario Universidad Surcolombiana
Ingenieria agricola
Enerode1985 - de 1991


ABDALLA, M. A. Determination of caffeine, the active ingredient in different coffee drinks and its characterization by FTIR/ATR and TGA/DTA. International Journal of Engineering and Applied Sciences, 2(12):85-89, 2015.

ALONSO, A. et al. Habituation of bean (Phaseolus vulgaris) cell cultures to quinclorac and analysis of the subsequent cell wall modifications. Annals of Botany, 101(9):1329-1339, 2008.

BAHAMÓN, A.; PARRADO, L.; GUTIÉRREZ, N. ATR-FTIR for discrimination of espresso and americano coffee pods. Coffee Science, 13(4):550-558, 2018.

BAJPAI, S. K.; BAJPAI, M.; RAI, N. Sorptive removal of ciprofoxacin hydrochloride from simulated wastewater using sawdust: Kinetic study and effect of pH. Water SA, 38(5):673-682, 2012.

BANERJEE, S.; CHATTOPADHYAYA, M. C. Adsorption characteristics for the removal of a toxic dye, tartrazine from aqueous solutions by a low cost agricultural by-product. Arabian Journal of Chemistry, 10:S1629-S1638, 2017.

BARBIN, D. F. et al. Application of infrared spectral techniques on quality and compositional attributes of coffee: An overview. Food Research International, 61:23-32, 2014.

BARRIOS, Y.; GUTIERREZ, N.; GIRON, J. Effect of the postharvest processing method on the biochemical composition and sensory analysis of arabica coffee. Engenharia Agricola, 40(2):177-183, 2020.

BARRIOS, Y.; SALAS, K.; GIRÓN, J. Comparison of sensory attributes and chemical markers of the infrared spectrum between defective and non-defective Colombian coffee samples. Coffee Science, 15:e151659, 2020.

BELAY, A.; KIM, H. K.; HWANG, Y. H. Binding of caffeine with caffeic acid and chlorogenic acid using fluorescence quenching, UV/vis and FTIR spectroscopic techniques. Luminescence, 31(2):565-572, 2016.

BRO, R.; SMILDE, A. K. Principal component analysis. Analytical Methods, 6:2812-2831, 2014.

COUTO, G. M. et al. Use of sawdust Eucalyptus sp. in the preparation of activated carbons. Ciência e Agrotecnologia, 36(1):69-77, 2012.

CRAIG, A. P. et al. Mid infrared spectroscopy and chemometrics as tools for the classification of roasted coffees by cup quality. Food Chemistry, 245:1052-1061, 2018.

CRAIG, A. P.; FRANCA, A. S.; OLIVEIRA, L. S. Discrimination between Immature and mature green coffees by attenuated total reflectance and diffuse reflectance fourier transform infrared spectroscopy. Journal of Food Science, 76(8):C1162-C1168, 2011.

CRAIG, A. P.; FRANCA, A. S.; OLIVEIRA, L. S. Discrimination between defective and non-defective roasted coffees by diffuse reflectance infrared Fourier transform spectroscopy. LWT-Food Science and Technology, 47(2):505-511, 2012.

DIAS, R. C. E. et al. Quantitative assessment of specific defects in roasted ground coffee via infrared-photoacoustic spectroscopy. Food Chemistry, 255:132-138, 2018.

EBRAHIMI-NAJAFABADI, H. et al. Detection of addition of barley to coffee using near infrared spectroscopy and chemometric techniques. Talanta, 99:175-179, 2012.

FERREIRA, T. et al. Three centuries on the science of coffee authenticity control. Food Research International, 149:110690, 2021.

FERREIRA, T. et al. Using Real-Time PCR as a tool for monitoring the authenticity of commercial coffees. Food chemistry, 199:433-438, 2016.

GALLIGNANI, M. et al. Determination of caffeine in coffee by means fourier transform infrared spectrometry. Revista Tecnica de La Facultad de Ingenieria Universidad Del Zulia, 31(2):159-168, 2008.

GARCIA, L. M. Z. et al. Chemometric evaluation of adulteration profile in coffee due to corn and husk by determining carbohydrates using HPAEC-PAD. Journal of Chromatographic Science, 47(9):825-832, 2009.

GARRIGUES, J. M. et al. Fourier transform infrared determination of caffeine in roasted coffee samples. Fresenius’ Journal of Analytical Chemistry, 366(3):319-322, 2000.

GORDILLO, F.; GARCÍA-SALCEDO, A.; MEJÍA-MORALES, C. Identificación de adulterantes soya, fríjol y cebada en café tostado y molido utilizando EFA-IRTF. Temas Agrarios, 17(1), 2012.

HAMEED, A. et al. Farm to consumer: factors affecting the organoleptic characteristics of coffee. II: Postharvest processing factors. Comprehensive Reviews in Food Science and Food Safety, 17(5):1184-1237, 2018.

INTERNATIONAL COFFEE ORGANIZATION - ICO. Crop year production by country. 2020. Available in: <>. Access in: july, 15, 2020a.

INTERNATIONAL COFFEE ORGANIZATION - ICO. World Coffee consumption for 2019/2020. 2020. Available in: < >. Access in: july, 15, 2020b.

LIANG, N. et al. Application of attenuated total reflectance-fourier transformed infrared (ATR-FTIR) spectroscopy to determine the chlorogenic acid isomer profile and antioxidant capacity of coffee beans. Journal of Agricultural and Food Chemistry, 64(3):681-689, 2016.

MILANI, M. I. et al. Authentication of roasted and ground coffee samples containing multiple adulterants using NMR and a chemometric approach. Food Control, 112:107104, 2020.

MORAIS, T. C. B. et al. A simple voltammetric electronic tongue for the analysis of coffee adulterations. Food Chemistry, 273:31-38, 2019.

MURRAY, J. M.; DELAHUNTY, C. M.; BAXTER, I. A. Descriptive sensory analysis: Past, present and future. Food Research International, 34(6):461-471, 2001.

NALLAN CHAKRAVARTULA, S. et al. Use of convolutional neural network (CNN) combined with FT-NIR spectroscopy to predict food adulteration: A case study on coffee. Food Control, 135:108816, 2022.

NEGI, A.; PARE, A.; MEENATCHI, R. Emerging techniques for adulterant authentication in spices and spice products. Food Control, 127:108113, 2021.

OHNSMANN, J. et al. Determination of caffeine in tea samples by fourier transform infrared spectrometry. Analytical and Bioanalytical Chemistry, 374(3):561-565, 2002.

OLIVEIRA, F. C. et al. Characterization of coffee (Coffea arabica) husk lignin and degradation products obtained after oxygen and alkali addition. Bioresource Technology, 257:172-180, 2018.

OLIVEIRA, R. C. et al. Evaluation of the potential of SPME-GC-MS and chemometrics to detect adulteration of ground roasted coffee with roasted barley. Journal of Food Composition and Analysis, 22(3):257-261, 2009.

PARADKAR, M. M.; IRUDAYARAJ, J. Rapid determination of caffeine content in soft drinks using FTIR-ATR spectroscopy. Food Chemistry, 78(2):261-266, 2002.

PAULI, E. D.; CRISTIANO, V.; NIXDORF, S. L. Method for determination of carbohydrates employed in the selection of adulterations in coffee. Quimica Nova, 34(4):689-694, 2011.

PHONPHUAK, N.; CHINDAPRASIRT, P. Types of waste, properties, and durability of pore-forming waste-based fired masonry bricks. In: PACHECO-TORDAL, et al. Eco-efficient masonry bricks and blocks: Design, properties and durability. Amsterdam: Elsevier Science, v1, p. 103-127, 2015.

PLANS, M. et al. Characterization of common beans (Phaseolus vulgaris L.) by infrared spectroscopy: Comparison of MIR, FT-NIR and dispersive NIR using portable and benchtop instruments. Food Research International, 54(2):1643-1651, 2013.

R CORE TEAM. R: A language and environment for statistical computing. 2021. R Foundation for Statistical Computing, Vienna, Austria. Available in: . Access in: July 27, 2022.

REIS, N.; FRANCA, A. S.; OLIVEIRA, L. S. Performance of diffuse reflectance infrared Fourier transform spectroscopy and chemometrics for detection of multiple adulterants in roasted and ground coffee. LWT - Food Science and Technology, 53(2):395-401, 2013a.

REIS, N.; FRANCA, A. S.; OLIVEIRA, L. S. Quantitative evaluation of multiple adulterants in roasted coffee by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and chemometrics. Talanta, 115:563-568, 2013b.

RIBEIRO, J. S.; SALVA, T. J.; FERREIRA, M. M. C. Chemometric studies for quality control of processed brazilian coffees using drifts. Journal of Food Quality, 33(2):212-227, 2010.

ROJAS, M. et al. Roasting impact on the chemical and physical structure of Criollo cocoa variety (Theobroma cacao L). Journal of Food Process Engineering, 43(6):e13400, 2020.

SANCHEZ, K.; CHAMBERS, E. How does product preparation affect sensory properties? An example with coffee. Journal of Sensory Studies, 30(6):499-511, 2015.

SANO, E. E.; ASSAD, E. D.; CUNHA, S. A. Quantifying adulteration in roast coffee powders by digital image processing. Journal of Food Quality, 26(2):123-134, 2003.

SEZER, B. et al. Coffee arabica adulteration: Detection of wheat, corn and chickpea. Food Chemistry, 264:142-148, 2018.

SINGH, B. R. et al. Determination of caffeine content in coffee using Fourier transform infra-red spectroscopy in combination with attenuated total reflectance technique: A bioanalytical chemistry experiment forbiochemists. Biochemical Education, 26(3):243-247, 1998.

STRUBINGER, A. et al. Valorization of waste from agro-industry using thermo-chemical treatments. WIT Transactions on Ecology and the Environment, 224(1):425-436, 2017.

SZAFRAN, M. et al. Ab initio and DFT calculations of the structure and vibrational spectra of trigonelline. Journal of Molecular Structure, 614(1-3):97-108, 2002.

TAVARES, K. M. et al. Free tocopherols as chemical markers for Arabica coffee adulteration with maize and coffee by-products. Food Control, 70:31-324, 2016.

ZHAO, C.; JIANG, E.; CHEN, A. Volatile production from pyrolysis of cellulose, hemicellulose and lignin. Journal of the Energy Institute, 90(6):902-913, 2017.




How to Cite

BARRIOS-RODRIGUEZ, Y. F.; DEVIA-RODRIGUEZ, Y. .; GUZMÁN, N. G. Detection of adulterated coffee by fourier-transform infrared (FTIR) spectroscopy associated with sensory analysis. Coffee Science - ISSN 1984-3909, [S. l.], v. 17, p. e171970, 2022. DOI: 10.25186/.v17i.1970. Disponível em: Acesso em: 25 sep. 2023.