Desenvolvimento de métodos utilizando HS-SPME/CG-EM para análise de HPAs em cafés

Abstract

Coffee is one of the most commercialized beverages in the world. According data from the International Coffee Organization, Brazil is the world's largest producer and exporter. Although some studies have pointed out the benefits of coffee for human health, the toxic properties of coffees are still not completely understood. It is understood that during the process of roasting your grains, the formation of several potentially carcinogenic substances can occur, including polycyclic aromatic hydrocarbons (PAHs), which are associated with the incidence of cancer in humans due to their mutagenic and carcinogenic potential. In addition, it is important to note that the chemical composition of coffee may change due to variations in the quality of the beans, thereby influencing its cytotoxic, mutagenic and genotoxic potential. This study aimed to perform qualitative and quantitative analysis of PAHs in coffee samples, using solid phase microextraction (SPME) and Gas Chromatography coupled to Mass Spectrometry (GC-MS) as well as to evaluate the presence profile and the levels of 16 priority PAHs in powdered coffees and drink preparations of high quality and common quality of these compounds in coffee preparations via chemometric method of multivariate analysis by principal component analysis (PCA). Ten samples of powdered coffee were used, divided into commercial and special quality samples. Samples were enumerated with codes so as not to reveal the manufacturers. High quality samples: AC, CL, O, H and ME and common quality samples: TC, SC, ML, PIL and KM, all from Brazilian producers. All samples belong to the species Coffea arabica. The preparation of the drinks was done with distilled water and following the instructions on the labels. The method was validated according to the parameters selectivity, linearity, detection limit (LD), quantification limit (LQ), precision and accuracy, the latter in terms of recovered percentage. Student's t test and Hartley's F test were applied to verify the significance of the parameters and the regression of the analytical curves obtained in the coffee matrix. The method for determining PAHs proved to be well suited for all sample determinations (analysis of powdered coffee, analysis of beverages prepared by infusion and cooking) and, in addition to being fast and sensitive, it uses a low amount of toxic solvents. The intra-run accuracies were in the range of 11-21%, 8-18% and 6-17%, respectively, for the levels 1, 2 and 3 evaluated. The detection limit and the quantification limit established for the analytes were lower than 0.39-2.02 μg kg-1 and 1.20-6.48 μg kg-1, respectively. PAH recoveries ranged from 53 to 126%, with a relative standard deviation < 20%. The method proved to be efficient when applied to detect and quantify 16 PAHs in 3 coffee samples obtained by different preparations. In high-quality samples were observed average concentrations of 0.9 to 1.4 μg kg-1 and 0.6 to 0.7 μg kg-1, respectively for naphthalene and fluorene and up to 2.8 μg kg-1 for fluoranthene. In samples of common quality in addition to the PAHs already mentioned, the compounds dibenzo[a,h]anthracene (averages 0.9 and 1.3 μg kg-1), benzo[g,h,i]perylene (0.5 to 1.4 μg kg-1) and indene were quantified in two samples indene[1,2,3-cd]pyrene (average of 1.3 μg kg-1 in samples obtained by infusion). The analyzes showed that high quality coffees in general showed a predominance of compounds with lower numbers of aromatic rings, while samples of common quality showed levels of compounds with a higher number of rings, with appreciable concentrations of PAHs with pentose ring, the which characterizes the addition of “non-coffee products” during manufacture.