Development of a new procedure for the determination of the reactivity of brandies used in wine fortification
Joana Azevedo,
João Pissarra,
Filipa Amaro,
Luis Guido,
Joana Oliveira,
Paulo Lopes,
Paula Guedes de Pinho,
Nuno Mateus,
Victor de Freitas
Affiliations
Joana Azevedo
LAQV – REQUIMTE - Laboratório Associado para a Química Verde- Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto
João Pissarra
UTAD- Universidade de Trás os Montes e Alto Douro, Quinta de Prados, Vila Real, Departamento de Agronomia, 5001-801 Vila Real
Filipa Amaro
UCIBIO@REQUIMTE/Laboratório de Toxicologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira, 228, 4050-313 Porto
Luis Guido
LAQV – REQUIMTE - Laboratório Associado para a Química Verde- Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto
Joana Oliveira
LAQV – REQUIMTE - Laboratório Associado para a Química Verde- Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto
Paulo Lopes
Amorim Cork S.A. Rua dos Corticeiros 830, 4536-904 Santa Maria de Lamas
Paula Guedes de Pinho
UCIBIO@REQUIMTE/Laboratório de Toxicologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira, 228, 4050-313 Porto
Nuno Mateus
LAQV – REQUIMTE - Laboratório Associado para a Química Verde- Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto
Victor de Freitas
LAQV – REQUIMTE - Laboratório Associado para a Química Verde- Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto
The main purpose of this work was to describe and validate a new methodology for the determination of a brandy reactivity index (BRI) towards flavan-3-ol compounds in wines (catechins and condensed tannins) and to correlate this index with the amount and type of aldehydes present in those brandies. This new method consists of two main reactions: a) the ability of aldehydes to react with C8 and/or C6 positions in the phloroglucinol ring of a catechin present in excess (A ring); b) further reaction of the remaining free catechin with p-dimethylaminocinamaldehyde (DMACA) yielding to the formation of a blue compound that can be quantified by Visible spectroscopy at 640 nm. The impact of different experimental conditions such as reagent concentrations and reaction time on BRI were also evaluated. The method was validated through the determination of repeatability (intra-day variability) and reproducibility. The repeatability was considered acceptable with a CV of 11.87 %. The analysis of the reproducibility variance, S2R (11.59), the reproducibility limit R (9.5) and the reproducibility coefficient of variation, CVR (15.25 %) postulates BRI methodology to be reliable and robust. Using the developed methodology, the BRI of fourteen different commercial brandies and some pure standards aldehydes were determined. The aldehydes present in brandies, and the content of total aldehydes were determined by GC-MS and then correlated with the BRI. In general, it was observed a direct correlation between the BRI and the concentration of total aldehydes, in particular acetaldehyde.
