FTIR and Chemometrics as Effective Tools in Predicting the Quality of Specialty Coffees

Cup tasting is the most important tool to access the quality of coffee beans. However, the use of sensory evaluation alone can present some problems, since bias from the previous knowledge of a particular sample and health conditions of the taster can influence the results. Given the well-established potential of spectroscopic methods in coffee quality evaluation, in the present study, we sought to evaluate the potential of FTIR spectroscopy for quantitative evaluation of specialty coffee quality. Samples of specialty coffee were provided by the Federacao dos Cafeicultores do Cerrado Mineiro and Fazenda Barinas. They were roasted in IKAWA coffee roaster, analyzed by a group of Q-graders, and submitted to FTIR analysis. Physicochemical analyses (pH, titratable acidity, brix, total solids, and browning compounds) were also employed to show potential differences. Only pH showed significant difference between the beverages. PLS results showed consistent models for predicting the quality previously given by the cuppers, with low values of RMSEC and RMSEP (0.23 both). Also, the models showed high values of Rc (0.99) and Rv (0.97). The whole spectra were considered as important to classify the coffees by their quality, showing the complexity of the beverage.