Characterization of mannoproteins during white wine (<em>Vitis vinifera</em> L. cv. ENCRUZADO) ageing on lees with stirring in oak wood barrels and in a stainless steel tank with oak staves

Aim: To compare the evolution of mannoproteins in a white wine submitted to two different stirring of lees processes: in French oak barrels (BA) and in a stainless steel tank equipped with French oak staves (IN). Methods and results: Total colloids were obtained by ultrafiltration and ethanol precipitation. Mannoproteins were isolated by adsorption on concanavalin-A and molecular weight separation. Sugar residues were characterized by GC analysis of their alditol acetates and protein content was determined according to Lowry method. Wines were submitted to sensory analysis. Conclusion: Three polysaccharide fractions were isolated from both BA and IN wines. Regarding sensory attributes, the only significant difference between BA and IN wines was the round mouth-feel. The BA wine showed a higher final polysaccharide concentration, which can be related to the rounder mouth-feel. Significance and impact of the study: This study is a technological approach of a process largely used by white wine producers who want to market a fresh wine produced with stirring of lees with a woody character. It reports the evolution of mannoproteins through four months of ageing on lees with two different stirring processes that can have a direct impact on the cost of the final product