Vitamin C or also E300 or ascorbic acid improves the protein in the flour to increase elasticity in the dough. A higher elasticity means that the dough can be stretched further without tearing. The bread can rise higher and keep more air.
Enzymes convert part of the flour into sugar which is used by yeast to make the dough rise (create air bubbles). Unused sugar can lead to a darker crust.
Example ingredients are:
Emulsifiers are used to mix water and liquid fat. Added fats can be mixed in the dough and improve the rise of the dough and make the crumb soft.
For home baking egg yolk can be used.
(Chinese: tangzhong, Japanese: yu-dane)
Flour is mixed 1:5 with water or milk and cooked at 65 deg C. The mixture holds moisture which improves the bread crumb to be softer and fluffier. It is a sort of béchamel sauce.
The mixture holds up to 2 days in the fridge. Salt can be added to increase this time and to speed up the hardening process after cooking.
In a dough the water roux should amount to at most 1-10% of the flour.