The blanching in boiling water kills the surface bacteria, so it should be for a full minute... a little longer won't hurt as long you (as suggested) immediately plunge them into cold water to stop the cooking.
Thereafter, we find that drying the beans slightly with paper towels and placing them on a tin sheet (used to bake cookies... err... biscuits here in the U.S.) and popping them into the freezer for couple of hours makes for a better bean than placing them all wet into freezer bags. After they're individually frozen place them in your freezer bags for further storage. As previously, I highly recommend investing in a vacuum sealer for extra protection of all frozen foods...