WildAgain Wildlife Rehabilitation, Inc.

Solubility test methodology

The equipment used for the solubility test is shown in the photo at right, which includes all of the following:


-          Milk replacer powder

-          Red scoop from Esbilac® can

-          Small glass jars*

-          Small wire whisk*

-          Digital kitchen thermometer*

-          10 ml graduated glass cylinders**

-          Small plastic funnel**

-          Test tube cleaning brush**


* Baby food jars work just fine and are easy to clean.

The whisk and thermometer are available at most kitchen stores.

** Available from Home Science Tools. Graduated 10 ml test tubes could be used, but these cylinders are easier to use since they have a free-standing base.


Test Methodology


Variables to assess

The tests were designed to visibly measure the affects of using different combinations of the following and as shown in the matrix at right:

- Water temperature at time of mixing

    (hot tap 125ºF; instant hot 175ºF)

- Hydration time (immediate; 4 hrs.)


For the immediate mix trials:

1.)     Powder was scooped into the small end of the red scoop provided in the Esbilac® can as shown above.

2.)     The powder was placed in a small glass jar and mixed 1:2 with either hot tap water (125ºF) or with much hotter water (175ºF) from an instant hot water dispenser. The temperature of the water was measured with the digital thermometer prior to mixing.

3.)     The formula was stirred for 30 seconds using the small wire whisk shown above.

4.)     The temperature of the formula was measured using the thermometer and recorded.

5.)     The formula was poured into a clean and dry graduated cylinder using the small plastic funnel shown above, filling to the 10 ml mark.

6.)     The cylinder was then placed in front of a tripod mounted SLR camera with a close-up lens.

7.)     Photos were taken immediately and then at 5, 10, 15, 20, 25 and 30-minute intervals.

8.)     The cylinder was then emptied and a photo taken of any visible residue on the side of the cylinder.

9.)     The cylinder was then rinsed with hot water, cleaned with the test tube brush, dried thoroughly, polished with a clean, lint-free towel, and allowed to come to room temperature prior to the next trial.

 Note: Each trial (steps #1-9 above) takes about 40 minutes to complete.


For the trials involving longer hydration times (4 hours):

Same procedure as described above, except for the following:

1.)     Instead of proceeding immediately to step #5 (above), the glass jar with the formula was covered with plastic wrap, and placed in the refrigerator (40ºF) for 4 hours.

2.)     After the designated hydration time, the jar of formula was removed from the refrigerator, stirred slightly, and warmed in a microwave to normal feeding temperature of approximately 100ºF.  Proceed with step #5 above.


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