Cross analytical and sensory differentiation of monovarietal white wines from four autochthonous grape varieties: focus on macromolecules

Abstract

White wines contain macromolecules such as proteins, phenolic compounds and polysaccharides. On a sensory level, these compounds contribute to the ‘mouthfeel’ that differentiates the white wines worldwide [1]. Separation methods such as Size Exclusion Chromatography (SEC) or High-Performance Liquid Chromatography (HPLC) are commonly used to analyse the macromolecular composition of wines [2,3]; However, macromolecular complexes can be denatured with these techniques, a barrier to evaluate precisely the contribution of macromolecules to wine properties. Asymmetrical Flow Field-Flow Fractionation (AF4) is an alternative promising separation technique to study wine macromolecules since it allows sample compounds separation by size with no stationary phase. Collected fractions integrity is thus preserved [4].

In France, 10 varieties of Vitis vinifera, out of around 250 listed, represent 75% of the national wine production [5]. French Southwest region has a real singularity with nearly 120 autochthonous varieties. In this study, 69 monovarietal white wines from four indigenous varieties (Colombard, Gros Manseng, Mauzac and Len de l’El) renowned for their specific taste properties were selected in different wineries from Tarn and Gers. Wines were analysed by Fourier Transform Infrared Spectroscopy to determine the conventional oenological parameters (alcohol content, titratable acidity, assimilable nitrogen, pH, residual sugars…). Then, their macromolecular profile was studied using AF4.

After statistical analysis, 3 wines were selected for each variety. A sensory Flash Profile test was set up using a trained panel to differentiate the 12 white wines according to their mouthfeel. Wines that stood out from the other wines on account of their sensory characteristics were analysed with the AF4. More specifically, the bitter flavour perception for Mauzac and Colombard wines differed strongly. The AF4 results highlighted different macromolecular profiles for these two varieties in terms of proteins, polysaccharides, and phenolic compounds. An SDS-page gel electrophoresis confirmed the observations for proteins, mannoproteins and polysaccharides.

Finally, the wines from Colombard and Mauzac were ultrafiltered at three different cut-off thresholds (100 kDa, 50 kDa and 30 kDa). The three collected fractions were tasted by the sensory panel and analysed thanks to the AF4. The expert panel could identify differences between the fractions for each variety, these results providing a new insight on the impact of macromolecules on white wines gustative properties.

References

[1] Gawel, R., Smith, P. A., Cicerale, S., & Keast, R. (2018). The mouthfeel of white wine. Critical Reviews in Food Science and Nutrition, 58(17), 2939-2956. https://doi.org/10.1080/10408398.2017.1346584

[2] Marangon, M., Van Sluyter, S. C., Haynes, P. A., & Waters, E. J. (2009). Grape and Wine Proteins : Their Fractionation by Hydrophobic Interaction Chromatography and Identification by Chromatographic and Proteomic Analysis. Journal of Agricultural and Food Chemistry, 57(10), 4415-4425. https://doi.org/10.1021/jf9000742

[3] López-Barajas, M., López-Tamames, E., & Buxaderas, S. (1998). Improved size-exclusion high-performance liquid chromatographic method for the simple analysis of grape juice and wine polysaccharides. Journal of Chromatography A, 823(1-2), 339-347. https://doi.org/10.1016/S0021-9673(98)00640-2

[4] Marassi, V., Marangon, M., Zattoni, A., Vincenzi, S., Versari, A., Reschiglian, P., Roda, B., & Curioni, A. (2021). Characterization of red wine native colloids by asymmetrical flow field-flow fractionation with online multidetection. Food Hydrocolloids, 110, 106204. https://doi.org/10.1016/j.foodhyd.2020.106204

[5] Frankel, C. (2013). Guide des cépages et des terroirs. Delachaux et Niestlé.