the material must be frozen before you vacuum seal otherwise you will have ice balls.breaking apart a giant chunk of ice is no fun. freeze material, once frozen vacuum seal. when loading column, you can do it the old fashioned way of brute force breaking up big cunks into smaller chunks. before opening sealed bag, gently but effectively smash it with a mallet repeatedly till big chunks are broken down.
if you have money to spend, buy a fritsche p19 with dry ice sleeve and appropriate cassette for cold. mill bio as needed.
There are many qualified members on this forum that will be happy to consult you on this. Find one in your area and get in touch.