I thought I'd try to build up a supply of expressed milk to mix with baby rice etc. when I start weaning my DS in a couple of months, as I'll be back at work by then. Will it still need to be frozen in sterilised ice cube trays if it's for when DS is six months plus?? I don't think my ice cube tray will fit in the steriliser. Also will it be OK to transfer the frozen cubes into freezer bags?