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What are the chemical reactions of adding alkaline substances to wheat flour dough and how does it change the properties and behavior? The same for acidic substances.

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(Alkani substances)[] are (basic)[], as opposite to (acid)[]. When you are asking "alkaline or acidic substances" are you meaning they are the same or different? I'm confused as the title only states "alkaline substances". – J.A.I.L. Nov 16 '12 at 10:03
Good remark, I'm going to rewrite my my question thank you. – Melara Nov 16 '12 at 23:42
Thank you for taking it in considetation. No it's a very clear question and (I think) a very good one. – J.A.I.L. Nov 17 '12 at 0:49

Alkaline solutions are added to wheat noodle dough when it is too be pulled by hand. The alkaline substance will break down the gluten connections to make a more pliable dough

See What flour and technique do I need for hand pulled noodles?

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I can think of adding alkali or acid substances mainly as means of changing the ph of the dough. And adding can be understood as in the dough, or on its surface.

Alkali/basic additives or ingredients

Acid additives or ingredients

Acids can also weaken the gluten, but in bread making is not so strange to add certain acids, or wanting an acidic dough.

  • One of the reasons on wanting an acidic final loaf is it will help increasing the shelf life, as it will act as a preservative.

  • Besides that, there is a very common acid used in doughs: Citric acid / Ascorbic acid / E-300. It helps the dough to rise more and faster, and be more manageable and have a crumb that resembles like cotton candy. You can read more on Ascorbic acid at the page of the Real Bread Campaign, and in this YouTube video you can see its effect in dough.

  • Another reason for wanting a low PH dough is to avoid starch degradation. Flours have enzymes (amylase) that end up degrading it. But that enzymatic activity is stopped with a PH<4.5. This is well known with 100% rye breads:

    I know the question states wheat flour, but this example is clarifier. Rye flour has low gluten, and it has a somehow "low quality" (if compared with "normal" wheat flour). Some recipes call for strong high gluten wheat flour to retain gas bubbles from the leavening that won't get trapped by rye's gluten. But in 100% rye breads gas can also be trapped. That is why usually rye breads are made with sourdough, which has acetic and lactic acids. They give the dough the right PH, and the starches in rye will get gelatinized and catch the gasses in a similar (although less effective way) than gluten. Sometimes, instead of sourdough, yeasts and acid are added as ingredients.

    That was an specific example with rye, but wheat flour also has starches, and they can also be gelatinized, giving a distinctive sourdough touch to to 100% wheat breads.

Acid and basic at the same time

(Thanks @ChrisSteinbach for reminding me it)

  • When mixing an acid and a base, a chemical reaction happens, neutralizing both and releasing CO2 gas:

    NaHCO3 + H+ → Na+ + CO2 + H2O

    That gas is employed to leaven the dough, as in a chemical leavener. I.E. in Irish bread or typical cakes.

Stuff that is not acid nor basic... yet

  • As a chemical leaveners improvement, one would like the reaction wouldn't start as soon as acid, base and water are mixed, but a bit later. This woud let some more time to work on the dough. Some salts have the characteristic of degrading at high temperatures into acid, helping (usually in the oven) for a second rise.
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A mixture of sodium bicarbonate (which is alkaline) and tartaric acid is commonly used as a chemical leavener in baking. If flour is mixed with small amounts of these substances, then carbon dioxide gas will form when water is added to the mixture creating small bubbles in the batter or dough. The mixture is typically cooked as soon as possible after the leavening agent is introduced so that the gas bubbles do not have time to escape and become baked-in.

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Thanks You set me on a cool direction. I found this site build that on what you are saying. – Melara Nov 17 '12 at 8:55

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