Why does bread structure weaken when wet (or cake, biscuit, corn puff, etc)?
This is really simple question, but I couldn't find answer myself for weeks.
First theory was that adding water dilutes concentration of rheology modifiers (gluten, starch, etc), reducing their rheology effects. But most gels aren't affected by adding water. For example, adding water to gelatin/agar gel doesn't weaken structure.
Second theory was that water replaces hydrogen bond holding amylose/amylopectin, reversing starch retrogradation to starch gelatinization. But I suspected if water would replace all hydrogen bonds within one second. Also, starch gelatinization(or reversal of starch retrogradation) requires heat, but cold water is enough to soften bread.
After reading 'why paper is weaker when wet' source1 source2, I think this theory is the most plausible explanation. Maybe water's electronegativity is so strong, it disrupts all hydrogen bond within a second. This would apply to most organic molecules, like cellulose (paper) and amylose/amylopectin (bread).
Third theory was that bread structure is maintained by bonds of molecules other than amylose/amylopectin. (Gluten, Maillard reaction products, or others?) And those molecules' bonds are instantly broken by water.
