What yeast species is named in croissant fermentation?

The yeast species named in croissant fermentation is Saccharomyces cerevisiae.

This species is commonly known as baker’s yeast. It is incorporated into croissant dough during predough preparation, before the butter-lamination and shaping stages. During proofing, the yeast metabolizes sugars and releases carbon dioxide, which expands existing gas cells and increases the dough’s volume.

When oxygen is available, Saccharomyces cerevisiae can respire, producing carbon dioxide and water. As oxygen becomes limited, it relies more on alcoholic fermentation, producing carbon dioxide and ethanol. The carbon dioxide helps leaven the dough, while steam from the butter and water provides additional lift in the oven.

Croissants therefore differ from yeast-free puff pastry: their flaky layers depend on both lamination and biological fermentation. Aspergillus and Penicillium are molds used in other food contexts, while Lactobacillus acidophilus is a bacterium, not the yeast species named in croissant production.