bread??

[eluned]

Bread is a staple food, and the simplest forms are made by cooking a dough of flour and water plus in most cases a leavening agent. Chemical leavening agents (baking soda and baking powder) can be used to replace yeast or mixed starter. Unleavened breads are not common, and many recipes tend to be like crackers.

Bread may be primarly starch, but to microorgaisms that isn't the same as pure sugar. Sugars are the simplest form of carbohydrates (usually made up of just one or two building blocks). Breads contain complex carbs - or long chains of these simple sugars. They can be broken down by enzymes (amylase) into sugars. Yeasts and other fungi produce enzmes that convert starches into the more readily digested simple sugars, but that takes time.

If you seriously want to compare the growth of mold in very basic bread made with and without yeast, you would need to start with an appropriate recipe for a yeast-free pan bread, flatbread, tortilla or matza (remember that buttermilk is a fermentation product) and then make a batch with and without added yeast.

A well designed experiment to evaluate the effect of the yeast only would use a recipe that included sugar. Each sample should be moistened. (Molds need moisture and unleavened bread is often very dry).

Keep reading your Harold McGee - he should also talk about the importance of gluten, and its development during kneading and resting of bread dough. Different wheats have different levels of gluten. Bread made from whole wheat also contains proteins and fats from the wheat germ.

[hunny]

One question to start with:
The bread with and without yeast were made with the same ingredients? Or just bought separately?

i made them myself..all the ingredients were same..

[Poison]

Baking powder does not replace yeast. Not the same.
The ingredients are the same, you just add some sugar for yeast, that's all.