Why is it permitted to drink wine on Passover when it is fermented with yeast?

So by your argument nutritional yeast products made from grape yeast should be OK for consumption on Passover? There is from of Marmite that is made from champagne grape yeast and this would be a very nutritious food to help vegans survive Passover.

Beer isn't kosher for Passover because it comes from fermented grains which is chametz. So although grains and grapes both contain yeasts not all yeasts are equal in the Torah's eyes.

The Torah forbids possession and consumption of chametz and yeast. Chametz is a fermented grain and yeast is the yeast found in the grain which causes the fermentation.
As the rabbi pointed out above, yeast used in kosher for Passover wine production is not collected from the grain; often and ideally it comes from the skin of the grape itself. That's why it is kosher for Passover. In other words: yeast in wine is not the yeast forbidden on Passover.

in your scenario the flour never leavened since it was baked to completion within 18 minutes. the definition of chametz is a dough (made of flour, from one of the grains listed in the Torah, and water) fermented 18 minutes. The Torah also and separately forbids possession and consumption of yeast collected from one of the five grains.

The reason wine is allowed and bread is not has nothing to do with Saccharomyces cerevisiae, the budding yeast, which happens to be my favourite fungi. It converts sugars and oxygen into alcohol and carbon dioxide.

chamets contain at least one of five types of grains outlined in the texts (spelt and rye have been added to the list as they didn't grow in Israel.) They cannot be left to rise for more than 18 minutes. There is no rising of wine, hence wine is allowed.

I hope that helps. Have a great pesach.

The reason beer is not kosher for Passover, is because of the malted barley and not because of the yeast.

You answer is incorrect, the same yeast that is used in the fermentation of beer is used in the fermentation of wine, as well as the raising of bread. The species is known as Saccharomyces cerevisiae. It is the species that converts carbs into alcohols and CO2.

As a side note, yeast wasn't known to be a part of the brewing process until 1857. So it sounds to me as if beer was deemed not kosher for passover as a more recent tradition. That or they excluded beer because it has grains in it.

Why not just have the lovely juice of the grape!
Grape juice . This is what we have every Passover. Not fermented, and not a problem to anyone, old or young, or those on medicines. May the Lord Bless your celebration at HIS feast.

Hey, Anonymous, I am the one who continually invokes science in the religious practice debunking process. You're stealing my show. ;)

What's this about yeast being the produce of the grains? It is a "plant" life that lives on the surface and extends tendrils into the grains in order to extract the sugars. In no way is it the "product" of the grains as it can exist apart from them. For example, I can take yeast from the surface of a grape and place it on a grain seed. It survives and multiplies with no problem. Also, this works the other way around.
Any home wine maker can tell you that wince can be made with baker's yeast (OK, not the best option and makes a poorer wine than that made with wine yeast but it does work!).
Surely it is the grain that is forbidden, not the yeast growing on the surface.