Assessment of Mineral Elements in Wine Spirits Aged with Chestnut Wood

Abstract

The mineral composition of wine spirit (WS) is of relevant interest due to its potential effect on physicochemical stability, sensory characteristics, and safety.1 Calcium (Ca) and iron (Fe) can form insoluble compounds, negatively affecting the WS clarity. Transition metals, e.g. Fe and copper (Cu), seem to play an important catalytic role on oxidation reactions involving phenolic compounds and other substrates for oxidation in WS. Other elements such as Cu, zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb), are of concern due to their toxicological or physiological properties. The ageing of WS is traditionally performed in wooden barrels. In spite of the high quality achieved by the WS, this is a time-consuming and costly ageing technology, among other drawbacks. For these reasons, in recent years, special attention has been devoted to alternative ageing technologies, namely the application of wood fragments to WS kept in stainless steel, often combined with micro-oxygenation (MOX). Having in mind that wood ash main inorganic components are potassium (K), Ca and magnesium (Mg), but also sodium (Na) and Fe, the potential transference of these and other metals to the WS during ageing is expected. However, in spite of substantial understanding of the organic extractable compounds, little has been published on mineral elements extraction from wood to WS and even to wine, 2,3 and with the exception of a recent study of the authors focused on Fe and Cu, no data is available for chestnut wood.4 This study, developed within the Project Oxyrebrand (https://projects.iniav.pt/oxyrebrand/index.php/pt/), aimed to examine the effect of WS’s ageing with chestnut wood (Castanea sativa Mill.), considering traditional and alternative technologies, on the beverage mineral composition. A wine distillate was aged in 250 L chestnut barrels (traditional ageing) and in 50 L glass demijohns with chestnut wood staves combined with three levels of MOX and nitrogen application (alternative ageing technology), with two replicates. Sampling was carried out after 3 weeks, 2, 6, 9 and 12 months of ageing, and the WS was assessed in terms of mineral elements composition by adapting an Q-ICP-MS semi-quantitative method previously developed and validated. 5 A full mass spectrum (m/z = 6–240, omitting the mass ranges 16–18; 40, 41, 211–229) was obtained by full mass range scanning. ANOVA was performed to examine the influence of the ageing modality and ageing time on the mineral composition. At the end of the ageing essay, and for most part of the elements, no significant differences between WS from different ageing modalities were found. Ageing time had significant effect on most of the elements, with different trends and distinct magnitude of changes being observed, depending on the element. In general, the concentrations of the mineral elements found in the WS were quite low, which is positive from the WS quality point of view.

References

1 Catarino S., Curvelo-Garcia A.S., Bruno de Sousa R., 2008. Contaminant elements in wines: A review. Ciência Téc. Vitiv., 23, 3-19.
2 Pilet A., Bruno de Sousa R., Ricardo-da-Silva J.M., Catarino S., 2019. Barrel-to-barrel variation of phenolic and mineral composition of red wine. Bio Web Conf., 12,  02011.
3 Kaya A., Bruno de Sousa R., Curvelo-Garcia A.S., Ricardo-da-Silva J.R., Catarino S., 2017. Effect of wood aging on mineral composition and wine 87Sr/86Sr isotopic ratio. J. Agric. Food Chem., 65, 4766-4776.
4 Canas S., Danalache F., Anjos O., Fernandes T.A., Caldeira I., Santos N., Fargeton N., Boissier B., Catarino S., 2020. Behaviour of Low Molecular Weight Compounds, Iron and Copper of Wine Spirit Aged with Chestnut Staves under Different Levels of Micro-Oxygenation. Molecules, 25, 5266.
5 Catarino S., Curvelo-Garcia A.S., Bruno de Sousa, R., 2006. Measurements of contaminant elements of wines by inductively coupled plasma mass spectrometry: a comparison of two calibration approaches. Talanta, 70, 1073–1080.