The natural yeast migrate from the skin of the grapes into the pulp, looking for water and oxygen, and the fermentation takes place.

"We allow the natural yeast on the grapes to carry out the fermentation," he said.

The apples have by then absorbed a natural yeast.

"I use natural yeast - no commercial yeast - for the fermentation," he said.

Also it is possible to create it in a baker's kitchen through natural wild yeasts.

Instead, natural yeast in the air converted it to a dark, bubbling brew that made whoever drank it feel good.

He uses natural yeast for fermentation, because commercial yeast can alter wine's traits.

It is brewed with natural yeast and Bavarian ingredients, and has an alcohol content of 5.5 percent.

If none were available, they would set up a number of vats, relying on natural airborne yeast to inoculate the brew.

John is equally forthright on the subject of levains, the natural airborne yeasts that bakers used to use for the fermentation process.