Bread and wine make fine companions in a picnic basket, but the two have more than that in common.

Microscopic Yeast Organisms

To make either one, the baker or the vintner has to enlist the help of yeast. Yeast isn't an important ingredient in the final product, but it's the biological processes of the microscopic yeast organisms that produce the alcohol and make the bread rise.

And in both cases, the yeast works by digesting the sugars in the recipe.

Different Products, Similar Process

Even though the final products are very different, the yeast acts in the same way whether in bread or in wine. When a vintner adds yeast to fresh grape juice, the yeast digests the natural sugars in the juice, breaking the sugar into two simpler chemicals: alcohol and carbon dioxide gas.

When the carbon dioxide bubbles to the surface, what's left is wine.

A baker adds yeast to a mixture of flour, water, and sugar for a very different reason, but the yeast does exactly the same thingit changes the sugar into alcohol and carbon dioxide. The carbon dioxide fills the dough with gas, making it rise. The alcohol then evaporates during baking.

Creating A Final Product

For the vintner, the yeast produces alcohol while the by-product is carbon dioxide. For the baker, the yeast produces carbon dioxide to make the bread rise, and produces alcohol as a by-product.

In short, the baker's by-product is the vintner's key ingredient, and the vintner's by-product is what makes the baker's bread rise.

If you cap the bottle before the yeast has finished, you can keep the carbon dioxide and the alcohol. The result is champagne.