QUALITY WATCH
What have we learned from LPC testing? WE ASKED THE EXPERTS:
Ben Chapin
Patti Huttula
Joe Packard
MMPA Field Services Manager
MMPA Novi Laboratory Supervisor
MMPA Member Representative
Lab Pasteurized Count (LPC) testing is a great tool in the assistance of troubleshooting systems and a way to monitor quality on the farm. These past several months your MMPA lab has been performing monthly LPC testing which has given the field staff the opportunity to educate members about LPCs. A critical piece to LPC results is to remember that these are the bacteria that survive pasteurization. Because they survive pasteurization, these bacteria can cause problems with the overall quality and shelf life of finished dairy products. Something I have experienced and learned over the past several years that can lead to elevated LPCs are extended milking times and milk filters, especially during the summer months. Farms whose milking times extend beyond 5 hours may consider changing the milk filter halfway through milking. Depending on the system this may or may not be possible, but we have seen this practice reduce LPCs. We are always learning more about bacteria and better ways to control them. Your MMPA team is here to assist in achieving the best quality possible. If you have quality or system washing concerns, contact your MMPA member representative and they will work with you on quality and system troubleshooting.
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milk messenger
/ JUL-AUG 2020
LPC is the number of bacteria per mL of milk which survive laboratory pasteurization. To perform the procedure, a portion of milk is aseptically dispensed into a sterile vial and then heated to 62.8° Celsius (143° Fahrenheit) for 30 minutes. The media is inoculated with a dilution of milk and then incubated for 48 hours after which the bacteria colonies are counted. The results range from 10 cfu/mL which is an indication of excellent quality to 1000 cfu/mL which would prompt the member to identify the root cause of the elevated result and take corrective actions. Approximately 2,600 LPC tests are performed each month.
Troubleshooting an elevated LPC can be a challenge to tackle on-farm. When helping a producer locate potential LPC issues in their system, I start with a thorough inspection of all equipment to make sure it is clean. Then, I inspect the rubber parts throughout the system, such as O-ring gaskets, lid gaskets, inflations, jetter cups and milk pump seals. As these parts break down, visible cracks and microscopic crevices form in the rubber. Bacteria love to find their way into these small, difficult-to-clean places which can cause high counts. If the system has an air blow installed, I also check the air blow filters to make sure they are clean and in good condition.
LPC special testing has been a service provided by the Novi Laboratory for many years. Since October 2019, we have run LPC testing on each member's milk at least once a month. For both special testing and routine testing, the test results flow through to the member. When viewing the “Details and Specials” section on the Member Portal, the test is listed as a PAST special where PAST stands for PASTEURIZED. The email notifications and mailers list the test as an LPC special. If you have any questions related to a test method or result, please contact the Novi Laboratory.
As with other bacteria-related issues, prevention is the best defense against high LPCs. Routine maintenance and replacement of parts is crucial to maintaining a low LPC. Air blow filters, O-ring gaskets, inflations, jetter cups and milk pump seals all have a recommended lifespan so producers should consult with their equipment dealers regarding these parts and replace them at regular intervals. If a producer is concerned about a potential cleaning issue, MMPA’s trained member representatives can perform a wash analysis on the pipeline and bulk tank to observe for problems during wash cycles.
