Vinegar might seem like a strange thing to go into bread, but it plays a few important roles. Vinegar makes the water in bread dough more acidic, and acidic water is desirable when baking bread because it encourages yeast growth. The vinegar also slows the molding process of the finished baked goods. Most recipes call for distilled white vinegar, but malt vinegar can be substituted.
Some bread recipes call for malt vinegar. If you want to substitute it for malt vinegar, you need to keep a few differences and one important similarity in mind. White vinegar is just 5 percent acetic acid and 95 percent water, and it is sourer than malt vinegar. Malt vinegar comes from a process that begins with malted barley and ends with sweet malt vinegar. Substituting malt vinegar for white vinegar alters the bread's flavors, making it slightly sweeter. Also, when substituting malt vinegar for white vinegar, make sure that the malt vinegar contains 5 percent acetic acid to give the dough the needed acidic level.