Determinação simultânea de esteviosídeo e rebaudiosídeo A em vinhos

Abstract

According to the Brazilian legislation, in order to obtain medium dry and sweet wines, there is just allowed to add sucrose to the wine before bottling. The addition of any other natural or synthetic sweetener in wine is considered an adulteration and to ensure that these products are in accordance to the law, reliable analytical methods capable of detecting the use of these substances are needed. The natural stevioside and rebaudioside A sweeteners, mainly found in the leaves of Stevia rebaudiana (Bertoni), have been widely used by the food and beverage industry in recent years. Therefore, the objective of this work was to develop a method by high performance liquid chromatography coupled to tandem mass spectrometry (HPLC MS/MS) using electrospray ionization (ESI) source, for the determination of stevioside and rebaudioside A sweeteners in wines. The HPLC separation was carried out on a C18 column with gradient elution of 0.1% formic acid (v/v) in water and 0.1% formic acid (v/v) in acetonitrile as mobile phase. The ionization source worked in negative ion mode and data acquisition under MS/MS was achieved by applying multiple reaction monitoring (MRM). To confirm that analytical method is suitable for its intended use, several validation parameters, such as linearity, limits of detection (LOD), limits of quantification (LOQ), recovery (accuracy) and repeatability (precision) were evaluated. The correlation coefficients (R²) of the calibration curve were 0.9981 for stevioside and 0.9979 for rebaudioside A, revealed a good linearity in the concentration range for each sweetener. LOD and LOQ were 4.56 mg.L-1 and 4.80 mg.L-1 for stevioside, respectively. For rebaudioside A, the LOD and LOQ were 4.46 mg.L-1 and 4.70 mg.L-1, respectively. The recovery ranged were between 83.70% and 106.58% and the coefficient of variation were (menor ou igual) 3.48%, for both of the sweeteners studied. There were analyzed 24 national commercial wine and sparkling wine samples and the sweeteners were not detected in any of the them, implying that all the samples were conforming to the law. The proposed method has been successfully applied to the determination of stevioside and rebaudioside A in wines, demonstrating the importance of developing this work since there is no official method for detecting these natural sweeteners in wines. [resumo fornecido pelo autor]