OPPOSITE: Making red and white wines. White
wines are fermented at a lower temperature
and without the grape skins and seeds; they’re
also clarified at a lower temperature, in part
so that they won’t cloud when served chilled.
Malolactic Fermentation Winemakers
sometimes allow or even induce a second
bacterial fermentation in the new wine after
the main yeast fermentation. The bacterium
Leuconostoc oenos consumes the wine’s malic
acid and converts it into lactic acid, which is
less strong and sour. This “malolactic”
fermentation thus reduces the apparent
tartness of the wine. It also produces a number
of distinctive aroma compounds, among them
buttery diacetyl. (A relative of L. oenos, L.
mesenteroides, contributes the same
compound to cultured butter itself!) Some
winemakers work to prevent a spontaneous
malolactic fermentation from developing, so
that they can retain the sharpness and flavor