Mannoproteins from oenological by-products as tartaric stabilization and color agents in white and red wines

Abstract

Climate change is drastically modifying grape composition and wine quality. As consequence, must and wines are becoming unbalanced, with high sugar concentration, increased alcohol content, lower acidity, excessive astringency, color instability and also a rise in the incidence of tartaric instability is being showed. The winemaking industry generates large quantities of byproducts, such as skins, grape pomace and lees, which represents an important environmental impact. In recent years, there has been increasing interest in the valorization of these byproducts, since contain high value-added compounds, such as polysaccharides among others [1]. Therefore, the obtention of polysaccharides from wine industry byproducts could diminish the environmental impact, enhance the sustainability in the wine industry byproducts, and also promote the circular economy due to the subsequent application in the winemaking process [2]. The aim of this study was to obtain mannoproteins from wine lees resulting from different winemaking processes and origins, as well as from the vinification of both white and red grapes, and to evaluate their influence on tartaric stability, color and phenolic composition in white and red wines. Thirteen different mannoproteins extracts (issued from wine lees) were characterized by SDS-PAGE, HPLC-RID and HPLC-MS. The analysed mannoproteins presented molecular weights between 160 kDa and 213 kDa and their protein content was ranging from 15 to 31% and had notable differences in their monosaccharide composition. Four mannoproteins with the highest and lowest average molecular weight and protein content were selected and each selected individual mannoprotein was added at a concentration 500 mg/L to white wine (cv Verdejo) and red wine (cv Tempranillo) in order to their effect on tartaric stability and phenolic composition at 0, 7, 14 and 40 days. Tartaric stability was assessed by a Cryosmart 2.0 equipment and color and phenolic compounds using CIELAB and HPLC-DAD-MS, respectively. The results showed that the addition of mannoproteins had an effect on the tartaric stability of white and red wines that depends on the structural characteristics of the mannoprotein. Similarly, differences in the phenolic profile and on color of the different wine samples were observed, that could be attributable to the effect of the mannoproteins and related to the differences presented in their structure.

References

[1] Canalejo, D., Guadalupe, Z., Martínez-Lapuente, L., Ayestarán, B., Pérez-Magariño, S., Doco T. Characerization of polysaccharide extracts recovered from different grape and winemaking products (2022). Food Research International, 157, 111480.

[2] García-Lomillo, J., González-Sanjosé, M.L. Applications of wine pomace in the food industry: approaches and functions (2017). Comprehensive Reviews in Food Science and Food Safety, 16, 3-22.