Autenticidade e controle de qualidade de sucos de uva utilizando Ressonância Magnética Nuclear 1H – metabolômica aplicada a avaliação de adulteração

Abstract

The production of whole juices ready for consumption is booming, considering that the healthy eating and concern for health and personal well-being has become a worldwide trend. Thus, these drinks have become a common target for adulteration, requiring a better control of these actions. The Nuclear Magnetic Resonance (NMR) has been used to control food quality, including to indicate possible fraud, mainly related to intentional additives in food. Based on this, the objective of this study was the application of 1H NMR analysis to identify possible food fraud in different types of grape juices. In order to that, glucose, fructose and sucrose patterns were tested, as well as 24 real samples acquired in Caxias do Sul markets. For analysis, the samples were prepared by diluting 20 [Microliter] of sample in 580 [Microliter] of deuterated water (D2O) and, subsequently submitted to 1H NMR analysis. From the obtained spectra, we have detected ethanol, malic, tartaric and citric acid, in addition to fructose and glucose. Obtained spectra for whole and nectar juices were compared in order to verify possible similarity between compositions. Thus, it was possible to verify the presence of sucrose in nectar samples, as well as in a sample indicated as whole juice (5A). This result indicates a possible fraud caused by the addition of sucrose to this sample. Also, it was possible to observe changes in the displacement of the characteristics signals of malic acid in apple juice samples when compared with whole grape juice samples. It can be explained due to the change of pH from the sample (average of 2,85 for grape juice and 3.96 for apple juice). Finally, the PCA chemometric analysis was applied to help on understanding the similarities between the samples. In summary, this work demonstrates that metabolites analysis by NMR, which is a robust technique, with few or no sample manipulation and preparation, is suitable for the study of grape juices quality control. [resumo fornecido pelo autor]