Powdered Milk Replacers - Storage Time and Temperature Make a Difference
Buy very fresh. Store cold, preferably very cold. Use promptly.
OK, but why all the fuss? Consider the following chart and the answer should be apparent.
All of the milk replacers discussed and tested on this website contain casein, a primary milk protein. The chart at right from a published research study concluded that the solubility of casein in MPC85 (Milk Protein Concentrate - 85% Protein) decreased as a function of both storage time (from initial manufacture) and storage temperature. While not shown on the chart, the study indicated that the solubility for a storage temp of 68°F decreased to 60% at 210 days (7 months).
If someone suggests that these powders can be stored at room temperature and used within an expiration date two years from today, the data in this study and this chart prompts questions. It also presents challenges and some controllable factors.
What we CANNOT control
This includes a variety of things:
1.) We do not know, much less control, the storage temp and time from when the milk was separated and dried until it was originally shipped to the manufacturing facility.
2.) We do not know the storage temp and time during shipping/transportation to the manufacturing facility. Consider that much of the bulk dried milk originates outside the USA, that could require considerable transit time (perhaps unrefrigerated) during warm periods of the year to arrive at a manufacturing/assembly facility.
3.) Once manufactured, we do not know how long the final milk replacer product remains at the manufacturer's facility after the date of manufacture prior to shipment to retailer (or direct sale to an end user) and at what temperature.
4.) We do not know long or at what temperature the milk replacer product has been warehoused at a third party retailer's warehouse prior to sale to an end user.
5.) We do not know under what conditions the milk replacer product was shipped from a third party vendor to an end user. It could be in a very hot plane or truck during shipping in August across the country, and then waiting longer in a distribution warehouse prior to final delivery.
Needless to say, there are many steps in chain of production/manufacture/warehousing/shipping prior to arriving in the end user's possession that we cannot control. But we can control some things.
What we CAN control
There are a few critical things we can control as a customer and a good planner.
1.) We can shop for and demand freshness when we purchase the product. The lot number on the product labeling indicates the date of manufacture. Ask to see the lot number and determine the date it was made. If it is months old, you are already behind the curve. Seek a product from a more currently manufactured lot.
2.) Immediately refrigerate or freeze the product. This should significantly arrest the reduction in casein solubility. Only remove the amount you will need to make the immediate batch of formula. Allow the powder to achieve room temp prior to mixing, which it should do fairly quickly.
3.) Use the can or package of powder sooner rather than later. Plan ahead and purchase only enough for the current busy season. Use last year's annual report records as a guide to estimate the required volume to purchase. Freeze leftovers, but keep in mind fresher is generally better.
While not directly influencing reconstitution efficiency, following the three preceding steps also helps inhibit the onset of or progression of rancidity in the high fat powdered milk replacer products. Learn more here.
References (not intended as an exhaustive list)
Anema, S. G., D. N. Pinder, R. J. Hunter, and Y. Hemar. Effects of storage temperature on the solubility of milk protein concentrate (MPC85). Food Hydrocolloids (2006) 20:386-393.