| Summary: | Detection and quantification of adulterants in processed coffee is very important, because some sensorial characteristics and grain size are readily reproducible with products as cereals, legumes, seeds, roots and bad quality coffee after roast and ground. In this work, spectral characteristics of medium-roasted coffee powder that was blended to different concentrations with barley, bean and soy, are defined. This was done using infrared photoacoustic (PA) spectroscopy with Fourier transform. The samples were placed into a PA cell, which was adapted to a spectrophotometer as accessory for measuring. Principal Component Analysis (PCA) was applied on the spectra derivatives in order to estimate the effect of each adulterant. It was noted from the spectra behavior and PCA, that some characteristics of coffee, related to lipids and carbohydrates content, are modified in a different way when it is blended with the adulterants in different proportions. This analysis strengthens the definition of criteria that can be used for discriminating roasted and ground coffee, according to the degree of purity.
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