why lipids come under acid insoluble fraction?
The size of lipids are much smaller compared to the other macro molecules.However lipids come under acid insoluble fraction.This is because in compounds lipids are present not only as such but alsoas structures like cell and other membranes..When we grind a tissue, cell membrane .etc will break and form vesicles which are not water soluble.Terefore this membrane fragments in the form of vesicles get separated along with acid insoluble pool.