Monday, October 14, 2013

Shock Loading Refrigerators
You are in a dairy utility room. A worker comes in with five gallons of colostrum fresh from the milking parlor. Open door of refrigerator, in goes the colostrum, close door of refrigerator. 

Question: What will happen inside the refrigerator during the next hour? Using two used refrigerators in good working condition I collected interior temperatures under selected loading conditions. I chose nursing bottles and a 5-gallon pail as containers. We chose loading volumes of three, four and five gallons of 90F colostrum. The data look like this:

                          Peak Interior Temperature of Refrigerator (F)
                                 Type of Container
                            5 Gallon        2Qt Nursing
                            Pail                Bottles
Volume     3         44.7               50.4
(Gallons)  4         47.5               54.6
                 5         48.3               59.4   
The interior temperature before opening the door to load the colostrum was approximately 34F. It is easy to see as the load volume increased the peak interior temperature inside the refrigerator went up.
Not so easy to anticipate is the significantly higher peak temperatures for colostrum stored in nursing bottles compared to the single  5-gallon pail. I placed all the bottles in the middle of the space pressed tightly against each other - in a cluster of 6, 8 or 10 bottles depending on the load volume.

On one hand, even if you follow similar "shock-loading" practices this probably will not ruin someone's lunch. On the other hand, if you have  temperature-sensitive products stored in this same refrigerator "yo-yo"ing up to around 60F once or twice a day may not be a best management practice.

By the way, when colostrum is chilled to 60F before loading, refrigerator interior temperatures do not follow this pattern.


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