Will Freezing Kill Mold on Bread?

Moldy bread is most certainly an unwelcome sight first thing in the morning. The presence of the greenish blue fungi typically means the moist bread has been left in a warm, confined environment for a day or two. If moisture and warmth lead to mold, the natural question might be whether the opposite -- a dry, frozen environment -- will destroy it.

...
A fine loaf of bread is easily spoiled by mold.

Will Freezing Really Kill Off Mold?

...
Mold is nobody's friend in the breadbox, but freezing won't banish it.

The straightforward answer is that freezing will not do the job. Freezing is merely a fungistatic measure: in other words, it stops the mold from growing but won't destroy it. Freezing will simply make the mold dormant.

Can the Rest of the Loaf Be Saved?

...
A small spot of mold probably means the whole loaf is affected.

It may be tempting to just toss out the moldy slices and eat the rest, especially if the other pieces appear perfectly edible. However, this is really not a good idea. Chances are high that microscopic mold spores are already on the pieces that seem unaffected.

Can I Delay Mold Growth on Bread?

...
Sourdough bread doesn't go moldy at all.

Mold grows in moist and slightly warm environments (70 to 75 degrees F). You can delay mold growth by choosing a drier bread or one that has preservatives -- not very appealing options at all. However, if you enjoy sourdough, mold need not be an issue. Sourdough bread can still go stale, but owing to its acidity and the presence of lactic acid bacteria, it's virtually mold resistant.