Excitation-emission fluorescence as a tool to assess the presence of grape-must caramel in PDO wine vinegars

•Addition of grape-must caramel is a common practice in PDO wine vinegar production.•Multidimensional fluorescence was studied for caramel detection and quantification.•Different multivariate data analysis were also assessed and compared.•Sensory effects of grape-must caramel addition in PDO vinegar’s quality were showed.•This open up a new means of establishing monitoring protocols or limits of addition. A practice in wine vinegar production is the addition of grape-must caramel to correct and unify the final colour of different batches. Although current legislation allows it, the effect in vinegars’ quality has not been studied yet and it can become a fraud when it is used to simulate the effect of a longer ageing. Therefore, the aim of this work was to assess multidimensional fluorescence as a cost-effective and fast technique for detecting and quantifying grape-must caramel in vinegars. Different amounts of grape-must caramel and multivariate data analysis, as Parallel Factor Analysis (PARAFAC), N-way partial least squares and partial least squares discrimination and regression (NPLS-DA, PLS-DA and NPLS) were studied. Triangle sensory test was also performed. Results demonstrated the ability of this methodology in the detection and quantification of grape-must caramel (low prediction errors, RMSEP ≈ 0.24) and the effects that grape-must caramel has upon a PDO vinegar’s final quality.