The sooner you get them blanched and into the freezer, the better. Wash, and trim the beans. Place in boiling water for three minutes. Remove and run under very cold water until cool. Drain, pat dry with a towel and pack in plastic freezer bags in small amounts removing as much air from bag as possible. Then, I place them in another bag as extra insurance. You don't need to do this, but it helps guard against freezer burn.
Do not add salt to cooking water, or cooked beans.
And yes, the purple beans are lovely, but they turn green just like any other once they hit the water.
