Five Macromolecular fractions differing in molecular weight (M.W.) and composition were separated from a Prosecco wine by ultrafiltration and Size Exclusion Chromatography (SEC) before and after 1 and 18 months of wine ageing on yeast lees. The SEC fractions, combined or alone, were back added to the ultrafiltered wine in order to assess their contribution to wine foamability. 

The results indicated that the highest M.W. fraction, containing the wine glycocompounds and comprising the yeast mannoproteins was that giving the highest foamability, whereas the wine proteins deriving from the grape berry did not foam. 

However, the combination of all the fractions gave a foamability higher than that provided by the glycocompounds, indicating a cooperative effects between these latter and the proteins of grape origin. 

This result can be explained by hypothesizing a molecular interaction leading to the formation of macromolecular complexes able to interact with the gas–wine interface

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