The milk can still be used to feed the baby as long as your baby accepts it. However, it differs from baby to baby. Frozen milk tastes really bad but its not because it is spoilt. My baby willingly accepts some packets of frozen ebm and downright rejects some of it, she prefers freshly expressed breast milk (like expressed the day before) or latch on, but there's also some babies who willingly accept their awful tasting frozen ebm as well. I saw your thread on buying mini freezer, I believe you will need to try it out and see if your baby likes frozen ebm before investing on a freezer for work.