Bread yeast

September 19, 2008 12:51 PM

Will the yeast in a loaf of bread eventually die or become inactive enough for a yeast free diet?

Have to eat a yeast free diet. A local bakery told me that the yeast in a loaf of bread is inactive a few days past the expiry date. Is this true?

posted by larry_darrell to food & drink (8 comments total)

I'm pretty certain that baking kills the yeast. It's a fairly delicate organism.
posted by dirtynumbangelboy at 1:01 PM on September 19, 2008

Yep, they're killed by the heat. That's why the bread no longer rises after you bake it.
posted by cerebus19 at 1:08 PM on September 19, 2008

The yeast in bread is definitely dead after baking.

The yeast in some beers is still viable in the bottle, so if you’re a beer drinker, stay away from the premium Belgians and stick to something pasteurized and artificially carbonated like Bud.
posted by ijoshua at 1:16 PM on September 19, 2008

There are also many varieties of unleavened or chemically leavened (baking powder) breads which have no yeast at all.
posted by ijoshua at 1:19 PM on September 19, 2008

As noted above, yeast are killed by heat. I suppose, if your bakery is sufficiently old-school, they may have wild yeast growing in their environment. In which case live yeast could get on the loaf, and thus need to be killed by time.

Yes, bakeries really can harbor wild yeast strains in great abundance. That's how it worked prior to the development of commercial yeast.

...but, for the most part, unless your bakery is super-artisanal, I probably wouldn't worry about it as the amount of yeast involved is (probably) tiny.
posted by aramaic at 1:53 PM on September 19, 2008

You sure you can eat dead yeast? I knew someone on a yeast free diet that couldn't eat bread.
posted by Not Supplied at 3:13 PM on September 19, 2008

It would depend on why this person is avoiding yeast.
posted by rxrfrx at 2:42 PM on September 21, 2008

The point of a yeast-free diet is to avoid foods that are made with yeast. Beer and bread are verboten at all times in a yeast-free diet. The yeasties may be dead, but the chemicals that they're made out of remain. You can taste them. And, they are what is to be avoided.
posted by Citrus at 9:54 AM on September 22, 2008