Excellent question. Storage is very important and differs based on the type of formula. Storing opened formula Ready-to-feed or Concentrate: Cover and store it up to 24 hours in the refrigerator. Powder: Once opened, use within one month. Store the container in a cool, dry place and make sure the lid is tightly closed*. Storing unopened formula Safe: Storing unopened formula in a cool, dry place (6º – 25ºC).  Alert: Storing formula over 37ºC for a few days may compromise its vitamin content. Safe: Storing unopened liquid tetras in the fridge, only if the temperature is expected to exceed 37ºC for a few days. Alert: You may see changes in the texture of the product after you refrigerate it—they’re merely “physical”. This means the product has not spoiled and its nutritional quality has not been affected. The product just needs to be shaken VERY WELL to break any soft lumps and reincorporate the formula.   Freezing unopened formula Alert: Freezing unopened powdered formula should only be done in an emergency. Safe: You need to ensure that any powdered formula you had to freeze is brought to room temperature before you mix it. Alert: Freezing unopened concentrated formula is not recommended—it may compromise the quality. The fat and protein might separate out of the formula and you’ll have trouble re-mixing it. Safe: Avoid storing unopened formula in any kind of extreme or inappropriate temperatures. *Formula storage instructions are stated based on Nestlé infant formula products. Please consult the label for full preparation and use instructions. If using another brand of infant formula, please follow the directions stated on the label.