Progressing fermentation was also a challenge in transporting bottled Federweisser over long distances before the advent of modern-day commercial traffic and refrigerated vehicles, the latter of which are needed to slow down the yeast's metabolism during transport. Therefore, in the old days, Federweisser was almost exclusively available (and, for the most part, known) in and around wine-growing regions. Depending on the date of the grape harvest, it is available from early September to late October, and is generally served together with savoury food. The classic combination is Federweißer and Zwiebelkuchen, although Federweißer and chestnuts is also popular. . In the south-western part of Germany and neighboring Alsace, it is accompanied by Flammkuchen. '''' Federweißer contains yeast, lactic acid bacteria, and a large amount of vitamin B1 and B2. See also Nouveau References German wine Wine styles