How long can formula be stored in fridge and freezer?

Question

Sometimes we make formula and later realize that kid isn't actually hungry. Formula is expensive so I would like to know for how much time is it safe to store it in fridge, and freezer?

Though it is written on the formula packet that we shouldn't be storing it, should the warning be taken too literally?

Answer 1

According to the USDA:

Storing Infant Formula

Store bottles of prepared infant formula in a properly functioning refrigerator until ready to use. Bacterial growth is reduced when infant formula is kept in a refrigerator at temperatures at 40 degrees Fahrenheit or below. (Use a special thermometer to test if the refrigerator is at the appropriate temperature.) Caregivers should always consult their health care provider and follow the manufacturer’s label instructions for infant formula storage procedures. In general, it is recommended that caregivers:

• Use refrigerated bottles of concentrated or ready-to-feed infant formula within 48 hours of preparation.
• Use refrigerated bottles of powdered infant formula within 24 hours of preparation.
• Open cans of concentrated or ready made infant formula should be covered, refrigerated, and used within 48 hours.
• Freezing infant formula is not recommended.
• Powdered infant formula should be tightly covered and stored in a cool, dry place and used within a month after opening.
• Discard any infant formula remaining after a feeding. The mixture of infant formula with saliva provides an ideal breeding ground for disease-causing micro-organisms.
• Infant formula that is removed from refrigeration should be used within 1 hour or discarded.
• Before reusing any bottles or their parts, they should be cleaned and sanitized.

The full 20-page document describes all aspects of formula feeding - different types of formula, what's in formula, information about milk, bottle feeding tips

Answer 2

According to the World Health Organization guidelines:

1. Discard any feed that has not been consumed within two hours from preparation (unless refrigerated).
2. Prepared feeds can be held in the refrigerator (≤5 °C) for up to 24 hours.
3. Discard all leftover feed.
4. Preferably, the hang-time for continuous or bolus feeds should be no more than two hours at room temperature.
5. Continuous or bolus feeds should not be warmed during feeding.

The reasons for this are:

Powdered infant formula (PIF) has been associated with serious illness and death in infants due to infections with Enterobacter sakazakii. During production, PIF can become contaminated with harmful bacteria, such as Enterobacter sakazakii and Salmonella enterica. This is because, using current manufacturing technology, it is not feasible to produce sterile PIF. During the preparation of PIF, inappropriate handling practices can exacerbate the problem.