Unlike a true sourdough, these recipes usually start with commercial yeast, and the production of lactobacillus is incidental.

True sourdough is entirely leavened by the starter; no commercial yeasts are added.

With occasional allowances for liquid content and temperature, the different forms of commercial yeast are generally considered interchangeable.

The resulting mixture, called a starter, can be used instead of commercial yeast to leaven bread.

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

During the first fermentation, within hours after grapes are picked, natural and commercial yeasts convert the fruit sugar to alcohol and carbon dioxide.

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

Most Balthazar breads are made with starter rather than commercial yeast.

However, the Barm Cake is more likely made from commercial yeast today.

All the breads are made in the French pain au levain style, meaning that commercial yeast is not used.