Zwickelbier is essentially an effervescent form of a Bavarian Kellerbier. Westheimer Wildschütz is the first Zwickelbier that is available in the North America. Zwickelbier is unfiltered and unpasteurized, but the maturation casks (or modern tanks) are bunged or capped (“gespundet” in German) just before the end of fermentation. This furthers the dissolution of carbon dioxide gas in the brew. As a result, Zwickelbier builds up effervescence and has a nice creamy head when poured into a glass. Gold Medal from German Agricultural Society.