What is the principle of alum foaming?

Alum (alum), alkali (soda ash) and salt (thick coarse salt) mixed in dough preparation generate gas under the action of water, which makes the dough swell. Alum and soda ash play an important role in the expansion process, and the reaction formula is kai (SO4) 412h2o+Na2CO3+H2O → AI (OH) 3+Na2SO4+K2SO4+CO2 ↑+H2O.

As can be seen from the above reaction formula, alum and alkali added during dough mixing react chemically under the action of water, and the product is aluminum hydroxide (also known as alum flower), which is a colloidal substance and makes the finished product soft; The sodium sulfate and potassium sulfate produced are harmless to human body and have no effect on dough. The salt added during dough mixing plays a role in increasing the toughness and strength of dough, which is convenient for the molding operation of products. Due to the interaction between aluminum hydroxide and carbon dioxide, the dough products fermented by alum, alkali and salt swell.