Análise da sazonalidade e regionalidade em suco de laranja natural por ressonância magnética nuclear (RMN) e quimiometria

Abstract

The Nuclear Magnetic Resonance (NMR) has been become increasingly helpful as an analytical tool to assess the food quality, specially to highlight fruit juice in the last few years. In this context, NMR has presented solutions to identify frauds such as addition of unauthorized or not allowed compounds in fruit juices, wines, honeys, spirits, coffees, olive oil, etc.. The development of databases is used for this purpose which enables to perform at the same time the quantification of large numbers of compounds into the samples, as well as to provide the information about origin, variety and type of fruit that were used throughout orange juice production. The purpose of this study was to evaluate the seasonality and regionality in fresh orange juice used to produce concentrated orange juice for exportation through the orange varieties hamlin, pera, natal, and valência (Citrus sinensis (L.) Osbeck). 1H NMR and 2D analysis enabled us to characterize more than 20 compounds in fresh orange juice, and also to quantify the content of sugars (sucrose, α and β-glucose, and fructose), acids (citric, malic, ascorbic, succinic, and γ-aminobutyric (GABA)), aminoacids (proline, arginine, alanine, threonine, and valine), ratio and ethanol. The seasonality effects were evaluated by using principal components analysis (PCA), where it was possible to determine that region 3 showed more explicity defined seasonality stages for the varieties pera, natal and valência across the 2014 harvest. In contrast, the hamlin type presented more defined seasonality stages in region 2 for 2014´s harvest. The 1H NMR allied to supervised analysis of Partial Least Squares Discriminant Analysis (PLS-DA) lead to development of models where it was possible to distinguish the year of harvest, type of orange (early or late), type of variety (hamlin, pera, natal or valência) and the region (1, 2 or 3) where the orange juice was obtained.