Question

why does amylopectin does not give blue black color with iodine>?

Answer 1

Dear Student,
Iodine in presence of KI forms a triiodide ion and this ion and amylose component of starch gives a intense bluish-black colour.
The amylose component of starch forms a soluble bluish black starch iodide complex because the amylose is a linear chain and the tri-iodide ion can easily slip inside the chain forming a complex which is blue-black in colour, while amylopectin is branched hence the iodide ion cannot move inside the amylopectin chain and therefore does not give a blue-black colour.
I hope this explains !
Regards!