Steamed dumpling packaging

We are trying to find a best way to package steamed dumpling with less or no crystals formation at all. Currently, we are steaming the dumpling and cooling it using blast chiller and then we immediately seal it in a pp tray and put it in the freezer. But following this way is creating crystal formation inside the package. Could you suggest a solution for this?

So, the center is still somewhat warm or at least higher than the exterior?  Why not blast freeze completely? and 

So, the center is still somewhat warm or at least higher than the exterior?  Why not blast freeze completely? and 

We do not have blast chiller that is why we had to blast chill the dumpling.