Métodos cromatográficos para avaliação de antraquinonas, HPA’S, atividade antioxidante e composição fenólica como instrumento de controle de qualidade do processamento alternativo de erva-mate

Abstract

The inactivation of deteriorating enzymes (peroxidases) in mate leaves is carried out at high temperatures in the process known in Brazil as sapeco. The temperatures used at 400-620 ° C produce pyrolysis compounds, such as Aromatic Polycyclic Hydrocarbons (PAHs), consisting of a broad class of organic compounds containing two or more condensed aromatic rings, generated from the incomplete combustion of organic matter comprising high mutagenic potential. The present study aimed to evaluate how an alternative bleaching process of water immersion acts on the inactivation of the peroxidase enzyme and on the levels of HPA's and anthraquinone compounds. The central rotational compound design was used to evaluate the effects of immersion time (30, 40, 60, 80 and 90 s) and temperature (80, 82, 87, 92 and 94 ° C) with 22 complete factorial arrangements (+ 1.41 and -1.41) and three central points. After the treatments, enzymatic activity was determined using colorimetric assay and the results indicated that the best condition for inactivation was obtained after treatment at 87 ° C for 90 s (activity of 0.062 mmol.L-1 ± 0.002). The coefficient of determination (R2) attests that 97.9% of the data variability can be explained by the proposed model, with temperature, extraction time and interaction between these factors being significant in the 95% confidence interval. Assessment of the presence of HPA's was performed by gas chromatography coupled to mass spectrometry, and the Anthraquinones via High Performance Liquid Chromatography, both methods attested to the absence of the compounds of interest following the alternative treatment process. The parameters for the validation of the chromatographic methods were satisfactory, being the extraction denominated QuEChERS the most appropriate for the HPA's and the solid-liquid extraction with methanol more appropriate for the anthraquinones, evaluated after a Simplex Centroide delineation using the solvents methanol, water and ethanol and the interaction between them. The determination of the antioxidant activity by the ABTS and DPPH radical sequestration methods, iron reduction, as well as the evaluation of the Total Phenolic Compounds contents were carried out using the yerba mate extracts from the weed industry (bleached and unbleached) ) and a commercial sample, resulting in similar values between the samples. The results obtained in this study attest that in the alternative treatment the peroxidase enzyme content was low, demonstrating that this class of enzymes can be inactivated without the use of the dehydration operation in direct contact of the leaves with the flame and smoke of the sapeco process, avoiding the contamination of the final product by the compounds from the incomplete combustion of organic matter. From the obtained results one can elaborate procedures that can be used as control of the quality of the processing to assure the quality of the final product.