Ben Chapin
MMPA Member Services Director
It’s hard to believe that summer is already upon us and after this past winter in the Midwest, it is a welcomed season. While we welcome
summer and continue to get field work completed, it is important to keep in mind the challenges of cooling milk and keeping it cold.
Over the years the first heat wave of summer would often bring milk cooling challenges across the area. This could happen for a variety of reasons including compressors not being properly ventilated for the season, low freon levels, restricted plate coolers, etc. The first heat wave often identified areas of milk cooling that may have been sufficient in the cooler weather but stressed the system when we entered summer heat. Unfortunately, this may have led to warm milk and a potential loss for the farm.
This can be avoided by taking time for preventative maintenance on your milk cooling systems. An inspection of the cooling system is a great first step including compressors, freon levels and plate coolers. If you have a temperature recording chart, compare charts from previous weeks or months and identify if it is taking longer to cool the milk down. This may help catch an issue that has slowly crept up.
Marc Roberts
Roberts Dairy Service Owner
Maintaining your milk cooling system’s efficiency is critical, especially when summer heat adds extra strain. Pre-cooling with well water can
significantly reduce the cooling load, removing up to 2/3 of the heat. To optimize this, flush the well water side of your pre-cooler to eliminate rust and mineral buildup that hinders heat transfer. Ensure all water lines to and from the unit are clear of obstructions caused by mineral deposits. Also, consider if your current milk flow rate exceeds your system’s capacity.
Regularly check refrigerant pressures and levels in your compressors. For water-cooled units, verify adequate water flow and a clean heat exchanger. Air-cooled compressors require clean condensers with straightened fins and unobstructed airflow. Ensure condenser fans and their controls are clean and functioning correctly. Many power providers offer rebates for cooling system tune-ups, so contact your local dairy equipment dealer for this service. Proactive maintenance ensures efficient cooling and protects milk quality during hot months.
Steve Lehman
MMPA Raw Milk Compliance Manager
Milk cooling, along with sanitary milking procedures and clean equipment are the three keys to producing top quality milk. Providing top
quality milk and milk products to our customers has enabled MMPA to become a preferred supplier of raw milk and milk products across the country. Milking procedures and equipment provide the “seed” for bacterial growth; compromised cooling magnifies the growth of bacteria that is present.
The Pasteurized Milk Ordinance (PMO) requires that milk be cooled to 50O F within 4 hours of the start of milking, and allows for an additional two hours to bring the milk to 45O F. The blend temperature must not exceed 50O F after the first milking. Keeping your mechanical cooling systems (compressors, chillers and bulk tank interval timers) operating properly, along with maximizing well water pre-cooling enables these temperatures to be met while obtaining the maximum efficiency of energy used.
Cooling milk quickly to 36-38O F or less enables milk to be sent to high value and long distance markets. While milk tankers are well insulated and cooling rinses are employed when practical, the milk still needs to absorb any heat remaining from tanker cleaning and storage in the summer sun.
This article was originally published in the May/June 2026 issue of the Milk Messenger. Subscribe »