Why does baby formula say do not freeze?

Yes you are OK. Freezing doesn't affect the nutrients like many people is guessing, the main reason they warn not to freeze is because if you do so, the formula will separate (water+solids) and will lose it's consistency. You can call any Baby Formula maker's 800 information number and they'll tell you the same thing. Freezing mostly affects taste and look of the food not it's nutritional value. Since you are mostly doing sweet potato then the freezing-separation-problem doesn't apply here. Just be careful when re-heating to make sure is cool before giving to the baby, so microwave is not advisable. EDIT The International Formula Council says: "Should Infant Formula Be Frozen? The use of infant formula after freezing is not recommended. Although freezing does not affect nutritional quality or sterility, physical separation of the product's components may occur." <a href="http://www.infantformula.org/faqs.html#14" rel="nofollow">http://www.infantformula.org/faqs.html#1...  more