We
have seen that the process of turning white Savagnin wine into yellow wine
is linked to the presence of a yeast flor which acts best
in ventilated places which may be subjected to notable temperature differences
(semi-underground cellars or ground-level storerooms, even lofts), in other
words, places which differ from those which are suitable for maturing other
wines.This yeast flor is carefully and regularly inspected during the six years of cask maturation. Its appearance which changes with the seasons and the storage conditions in tune with the yeasts’ lifecycle provide valuable information about the development of the wine. By examining the flor regularly and tasting the maturing wine growers can detect the appearance and development of the "yellow wine flavour", or a change towards the vinegary taste.
Many wine-growers supplement their own observations with assistance from the Departmental Analytical Laboratory in Poligny which analyses the samples taken twice a year, in Spring and Autumn, to measure the volatile acidity and ethanol content. If the contents of the cask are not becoming "yellow wine" or if there is a risk of adulteration or browning, it is withdrawn from maturation at once. Nothing more can be done.
Yellow wine is therefore just as much a product of the vagaries of nature as the child of shrewd know-how.
