Ecological viticulture represent an upward trend in many countries. Unlike conventional viticulture, it avoids the use of chemical fertilizers and other additives, minimizing the impact of chemicals on the environment and human health. The aim of this study was to investigate the influence of nanofiltration (NF) process on volatiles and chemical composition of conventional and ecological Cabernet Sauvignon red wine. The NF process was conducted on laboratory Alfa Laval LabUnit M20 (De Danske Sukkerfabrikker, Nakskov, Denmark) equipped with six NF M20 membranes in a plate module, at two temperature regimes, with and without cooling and four pressures (2.5, 3.5, 4.5 and 5.5 MPa). Different processing parameters significantly influenced the permeate flux which increased when higher pressure was applied. In initial wines and obtained retentates, volatile compounds, chemical composition and elements concentration were determined. The results showed that the higher pressure and retentate cooling was more favourable for total volatiles retention than lower pressure and higher temperature. Individual compound retention depended on its chemical properties, applied processing parameters and wine composition. Nanofiltration process resulted in lower concentrations of ethanol, acetic acid (>50%), 4-ethylphenol and 4-ethylguaiacol (>90%). Different composition of initial feed (conventional and ecological wine) had an important impact on retention of elements.
The elemental composition
has been extensively used to characterize
wine and to find correlations with environmental and winemaking factors.
Although X-ray fluorescence (XRF) techniques offer many advantages,
they have been rarely used for wine analysis. Here, we show the comparison
of wine elemental composition results obtained by total reflection
X-ray fluorescence (TXRF) and energy dispersive X-ray fluorescence
(EDXRF) for elements K, Ca, Mn, Fe, Cu, Zn, Br, Rb, and Sr. The results
obtained by TXRF and EDXRF have been additionally verified by inductively
coupled plasma–mass spectrometry. The important analytical
features of XRF techniques in wine science have been described, the
preservation of volatile elements (e.g., Br) being one of their main
advantages. In addition, we have shown that XRF techniques offer an
optimal analytical approach for building large data sets containing
highly reliable and reproducible results of elemental abundances in
wines, corresponding soils, and grape juice. Such data sets are especially
important for the geographic authentication of wine. This has been
shown for 37 Austrian and Croatian wines collected together with respective
soils from selected wine regions. The element abundances in soil reflect
in a large portion in grape juice and finished wine suggesting that
the contribution of the soil, that is, the plant uptake capacity expressed
as c
i(wine)/c
i(soil) concentration factors, can be a highly discriminating factor
for wine fingerprinting. This indeed has been proved in the present
study in comparison to discrimination based only on wine element abundances.
We have identified Fe, Zn, Br, Rb, and Sr as the best discriminator
elements for the geographical authentication of wine. The study opens
a new perspective in extending the application of XRF techniques as
a cost-effective analytical tool for creating large databases of soil,
grape juice, and wine element abundances for the evaluation of soil
characteristics and other environmental parameters on wine composition.
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