Trace elements quantification in Portuguese red wines

• Author(s): Santos, Susana Isabel Barros dos
• Date: 2011
• Persistent ID: http://hdl.handle.net/10362/6276
• Origin: Repositório Institucional da UNL
• Subject(s): Portuguese red wines; Trace elements; Atomic absorption spectrometry; Target hazard quotients
• Document Type: Master thesis
• Language: English
• Advisor(s): Lapa, Nuno
• Contributor(s): RUN

Description

Dissertation for the Degree of Master in Technology and Food Safety – Food Quality

The aim of this thesis is to characterize Portuguese red wines in terms of trace elements composition. The wines were chosen so that all the country was represented and studied. For trace elements quantification (As, Hg, Cd, Ni and Pb) were tested various sample treatments including for all trace elements: acid digestion or presence and absence of spike. The need for H2O2 addition in order to oxidize organic compounds was analyzed for Hg, Cd, Ni and Pb. Quantification of all trace elements was performed with Atomic Absorption Spectrometry techniques. After the method validation were analyzed 25 Portuguese red wines and duplicates. The concentrations obtained were used to perform a statistical analysis to determine what were the regions with highest incidence of each trace element. Using Target Hazard Quotient (THQ) equation was possible to identify the regions where the concentrations found are a reason for public health concern, being values above 1 a motive for concern. After the analysis was determined that there is no need for wine samples digestion and that the presence of H2O2 is crucial. Hg and As were quantified with Hydride Generation Atomic Absorption Spectrometry; Ni and Pb with Flame Atomic Absorption Spectrometry; Cd with Electrothermal Atomic Absorption Spectrometry. The statistical results allowed to conclude that the system variation was mainly explained by the variation of Ni, As and Hg concentrations. Ni was largely found in Estremadura and Terras do Sado wines, while As and Hg were found mostly in Minho and Douro wines respectively. All of THQs determined were under 1, which is the limit value above which there is reason for health concern. Maximum THQ values were of 0.044 in Algarve wines were due to Ni.