In our regular test schedule for September we had a high test for coloform bacteria of 100 colony forming units per milliliter (CFU/ml). Coloform bacteria is an indication of dirt or other natural contamination. The specification is coloforms of a rolling three‐ month average of less than 25 CFU/ml. The overall bacteria was low at 370 CFU/ml compared to a specification of 15,000 CFU/ml and low compared to our other testing.
This was our first test that caused us alarm. Our protocol is to retest right away. The retests were better from October 4th with 20 CFU/ml and October 5 with 20 CFU/ml. Both samples had extremely low over all counts of only 80 CFU/ml each. The coloform count was within the specification but higher than our average. The only mitigating factor is that our family consumes the majority of the milk production. None of us were having issues. However, we certainly had our call to action.
The ability to recall milk or warn members is limited because the delay from testing. The first test results do not arrive for nearly 5 days after delivery. Given our size, we know which days milk goes to each specific member. By the time we notified the member, she had consumed the milk. The operation is just to small to be able test each day. Even with monthly testing, members are taking on some level risk in consuming raw milk.
Olivia and I also started digging in to what might have caused a change in the testing results. We have not changed our process significantly since last spring. The only addition was Bon Ami to clean the wax marker off the tops. The ingredients in Bon Ami would not cause coloform bacteria. We reviewed our process and observed each other to see if we could find a weakness in the process. One weakness we discovered is the possibility to drip water from the ice bath into the milk when pouring into the filter. We did get a clue from the OSU Vet school technician that asked if the sample was refrigerated. We did have reports and observations of milk being frozen in the refrigerator. So I figured the refrigerator was just too cold because of the on set of colder weather. So I kept turning it warmer. Finally I had a good look inside the refrigerator and found the thermo couple had come loose from the holder allowing it to hang in the air. I put it back and used a thermometer to measure the temperature. The temperature was about 45 degrees Fahrenheit. So the refrigerator is a likely cause. We have it all set properly now.
Our test results with the refrigerator working correctly and the care to keep the ice water out of the milk were back to normal with no coloform bacteria detected and a very low over all.