Baking Science

So iirc, the ingredients that cause bread to rise and become fluffy is simply a reaction between an alkaline and an acid. Raw eggs are slightly alkaline.
So knowing this, the possible combinations that can cause bread to rise are:
Baking Soda + Vinegar
Eggs + Vinegar
Milk + Bakingsoda?
Milk + Eggs
Yeast + ???
Yeast by itself

Is this correct?

Leavening by the chemical action of things like baking powder or baking soda happens in so called “quick breads”. Baking powder contains baking soda plus its own acid - they are inert until wet. Baking soda needs something acidic in one of the ingredients (usually lactic acid) to react with. Vinegar would certainly work, but I don’t usually think of it being used in bread. Irish Soda Bread usually has buttermilk in it, for instance, which provides lactic acid.

Yeast are living organisms which cause the bread to rise by eating sugars or starches in the dough and emitting CO2.

There are a few other ways of leavening. Recent thread:

Would regular whole milk suffice instead of buttermilk for most breads?

An acid - alkaline (aka acid-base) reaction does not intrinsically cause the production of gas, and isn’t the core reason for breads rising. It is a precondition for some ways of creating carbon dioxide - those that typically involve sodium bicarbonate of the like. It is the breakdown of sodium bicarbonate (aka baking soda) that yields carbon dioxide that raises the bread. Yeast produces carbon dioxide for quite different reasons. Sodium bicarbonate breaks down in an acid - base reaction, and so needs an acid for the reaction to work. Either you have an acid already in with the sodium bicarbonate, (in which case it is called baking powder) or you add it explicitly in the ingredients. But if you use most other alkalis, you won’t get any gas released, and no rise.

Beaten emulsions that have air entrapped within rise when cooked with no source of additional gas beyond heating of the entrapped air and some water vapour. For instance meringues and soufflés. The trick here is that the cooked material sets whilst risen, and holds it shape afterwards. Otherwise the drop in temperature would simply contract the final dish. Which is why they are not trivial things to prepare.

Yeasts convert sugars to carbon dioxide as part of their metabolic processes. So you need something to feed the yeast, otherwise the bread won’t rise. Typically you add a little sugar. It isn’t an acid-base reaction, but vastly more complicated.

You won’t get a nice rising bread unless it has been properly kneaded. You need to seed the structure of the bread with tiny pockets that the CO[sub]2[/sub] will fill. If you don’t, the gas just blows a small number of larger holes, and you don’t get the desired consistency.

If it’s a yeasted bread, sure. But it won’t taste exactly the same.

Buttermilk is acidic. It wI’ll react with baking soda to form carbon dioxide bubbles, which makes the bread rise. If you substitute something that isn’t acidic, you have to add an acid to get the same reaction. Cream of tartar is powdered tartaric acid. Mix acid powder and soda and you’ve got baking powder.

Another method would be foaming egg whites and folding them in. This this the method the ancient Israelites used when fleeing Egypt and didn’t have time to let their bread rise.

So what do eggs react with when they are an ingredient?
Can eggs release CO2 when they react with X ?

Nothing. Eggs supply protein that coagulates and sets. If you foam them up they will expand a little and set such as a meringue or a soufflé. They don’t provide a chemical raising function. No CO[sub]2[/sub]. If you want that along with eggs as a binder, you need to add it separately.

Neither milk nor buttermilk on their own will cause dough to rise. In combination with baking soda, buttermilk will allow leavening, but not milk. Baking powder (not plain soda) can do it all by its lonesome.

Acid speeds up the release of CO2 from baking soda, however, the heat of baking alone will do the trick, together with the moisture from other ingredients. However, since this makes the baked goods more alkaline, adding a little bit of an acidic ingredient will improve the taste, as alkalic goods have a hint of a soapy taste.

Eggs mainly help to solidify the dough, stick the flour together and capture the CO2 produced by the baking soda, which might otherwise just bubble out of the dough.
In yeast bread, extensive kneading releases the protein gluten from the flour, which served the same purpose as the egg in cake dough: It glues the starch particles of the flour together, capturing the CO2 produced by the yeast and solidifies as the bread is baked.

You can use ammonium carbonate, which decomposes on heating to ammonia and carbon dioxide. AFAIK only used in thin cookies (one typically wants the ammonia to dissipate) but I’ve never actually used it.

This also applies to single and double-acting baking powder.

CMC fnord!

Eggs don’t release CO2 at all. What they do is provide structure, so that bubbles can set up and harden rather than immediately collapsing.

Now, in some baked things with eggs, there’s expanding steam from the water in the batter, and the eggs provide enough structure that this steam is enough to raise the batter, even without any CO2 leavener (neither yeast nor chemical). Popovers/Yorkshire pudding is the best example, along with eclair/cream puff dough and some deep-fry batters.

  1. Mechanically. Air bubbles and moisture expand or are converted to steam when heat is applied. This creates a high pressure region which pushes against the dough causing it to expand.

  2. Chemically. You put chemicals in the dough that react together emitting gas. Heat spreads up the reaction, releasing more gases. Mechanical expansion continues from there.

  3. Microbially. Yeast and/or bacteria consume elements of the dough releasing gases and alcohol, causing the dough to rise. When heat is applied these microbes go into a feeding frenzy before they die and then mechanical action takes over as the gases and alcohol they emitted expand under heat

  4. It gets its back broken by Bane and then thrown into a hellhole in Calcutta. It hears an inspiring story about a child climbing out without using a rope. The rest of the prisoners yell at it to rise, and then it does.
    Getting prisoners to yell at your dough is rarely used these days.

Are there any vegans who reject bread because making one loaf requires killing millions of yeast cells?

Do you know any vegans who won’t eat fungus? I don’t.

I’ve used for knowledge on ingredient interaction. It has pictures comparing various reactions, but I think you have to search by what you are actually baking. Since I bake mostly cookies, my desired effect may be different than say a cake or a loaf of bread.