Whether you are a farmer using a simple bucket milker or a more complex pipeline milking system, cleanliness of equipment is a top priority for low-risk raw milk. Improper cleaning of milking equipment can lead to increased bacteria counts in the milk, off flavors, shortened shelf life, and increased likelihood that there will be pathogens present in the milk. Milking equipment needs to be cleaned after every milking.

Clean milking equipment is part of an overall goal for ensuring that there will be very little bacteria growth in the milk. When bacteria counts are low and the milk is kept properly chilled, raw milk will stay fresh for at least 2-3 weeks, with the delicious flavor that keeps your customers coming back over and over again.

Example of an Effective Cleaning Process for Milking Equipment and Bulk Tanks

Cleaning Process	Purpose	Notes
1. Flush with lukewarm water	Rinse away milk and organic debris	It is very important that the first rinse is done with lukewarm water. Otherwise, the milk may coagulate and stick to the equipment surfaces.
2. Hot alkaline wash	Remove bacteria, protein, fat, and biofilms from the equipment surfaces	Dairy detergent and most soaps are alkaline cleaners. Bucket milkers and tank valves should be disassembled and scrubbed clean with hot soapy water. Pipeline systems rely on turbulent flow of hot soapy solution through the clean-in-place system. The temperature of the soapy water needs to be at least 120 F at the outlet of the system to prevent milk solids from re-adhering to surfaces.
3. Warm acid rinse	Lower the pH of the equipment surfaces to create an environment that is unfavorable for bacterial growth	Most bacteria grow best in neutral pH environments. Using an acid rinse as the last cleaning step makes bacterial growth less likely to occur in-between usage of the equipment. Ideally, the acid rinse should have a pH of 3-4.
4. Dry	Remove moisture to make it hard for bacteria to grow	Invert equipment such as inflations and milk buckets to allow them to drip dry between uses. Completely dry milk tanks and valve parts between uses. Avoid having low spots where moisture can accumulate in pipeline systems.
5. Sanitize just prior to milking (optional)	Inactivate any bacteria that have grown in the system in between milkings	Pipeline systems, and especially pipeline systems being used only once per day, may necessitate the use of a sanitizer rinse just prior to milking. Simple bucket milker systems and pipeline systems being used more than once per day may not need to use a sanitizer prior to milking. This can be confirmed through coliform and Standard Plate Count testing. Some states require a sanitizer be used on milking equipment just before milking. Care needs to be taken to ensure that no more than the proper amount of sanitizer is used, to ensure that no undesirable residues end up in the milk.

Download Example Cleaning Process

Biofilms Provide a Place for Bacteria to Grow

Biofilms are symbiotic colonies of bacteria that can adhere to the inside of the milk lines, valves, crevices, etc. Through a process called quorum sensing, bacteria within biofilms are protected with multi-species cooperation. This makes the bacteria in biofilms hard to remove and destroy.

Biofilms can provide a safe haven for the growth of pathogens such as E. coli 0157:H7, Campylobacter spp., Listeria monocytogenes, and Salmonella spp. As biofilms grow larger, pieces of biofilm can break off when milk flows through the system, leading to contaminated milk.

Cleaning to Prevent Biofilms

Preventing biofilms in bucket milker systems is fairly simple since the components can be disassembled and scrubbed clean after every milking. However, milk pipeline systems require extra care to ensure that biofilms do not grow in the system. Since it is not possible to manually scrub the internal surfaces of the pipeline system, the cleaning process relies on turbulent flow of hot liquid cleaning solutions to wash away any bacteria in the lines.

Valves, gaskets, low points, and bends in the system create opportunities for biofilm growth. Pipeline systems need to be designed to minimize bends and ensure there are no low points where moisture can accumulate in the system. Valves and gaskets need to be completely disassembled and cleaned often to prevent biofilm growth. This includes the valve on the bulk tank, which should be completely disassembled and cleaned every time the milk tank is emptied.

Periodically Change Cleaners to Prevent Biofilm Growth

The use of both alkaline and acid cleaners will help prevent biofilm growth. Nonetheless, over time biofilms can become resistant to specific cleaners, especially in pipeline systems. Therefore, it is recommended to periodically “shock” the system by using different alkaline and acid cleaners about once a month. Simple bucket milker systems may not need to periodically alter their cleaners since they are completely disassembled and manually scrubbed after each use.

NOTE: Quaternary ammonias are not recommended for cleaning milking equipment because they are difficult to fully remove and can linger on the equipment.

Aim for “Kitchen Clean”

The main goal when cleaning milking equipment is to achieve “kitchen clean.” There is no need to go overboard by using high concentrations of harsh cleaners. If you overdo it, your cleaning processes can lead to early degradation of your milking equipment as well as unhealthy residual components in the milk.

Aim instead to find a good balance where you are cleaning your milking equipment enough to be clean and dry like the dishes in your kitchen.

Lukewarm Water First, Then Hot Cleaner

Make sure that the first rinse of the milking equipment is performed with lukewarm water. This will allow the residual milk to wash away without coagulating on the internal surfaces of your milking equipment. Using water that is too hot or too cold can result in the milk adhering to the internal surfaces of the milking equipment.

Once the initial rinse is completed, it is important to use hot alkaline cleaning solutions to ensure that fats and bacteria are washed out of the system. Bucket milkers and tank valves should be disassembled and scrubbed clean with hot soapy water. A pump can also be used to circulate the hot cleaning solution through bucket milker systems.

For clean-in-place systems, the temperature of the cleaning solution needs to be measured to ensure it is still at least 120 F at the outlet of the system.

Acid Rinse

Using a warm acid rinse as the last step in the cleaning process is important for minimizing bacteria growth in the system in-between milkings. Most bacteria grow best in neutral pH environments, so ending with an acid rinse creates an environment in which bacteria are less likely to proliferate. Ideally, the acid rinse should have a pH of 3-4 for the greatest effectiveness.

Drying

Allowing milking equipment, buckets, and tanks to fully dry in-between uses is another important step in limiting bacteria growth in-between milkings. Milk buckets, hoses, and inflations should be inverted to allow them to drip dry.

Complex pipeline systems may not be able to be dried completely between uses. These systems will need to rely on acids and sanitizers to ensure that bacteria counts remain low. Additionally, these systems should be designed to avoid low points where moisture can accumulate.

Sanitize Prior to Milking (Optional)

Some systems, such as pipeline systems being used only once per day, will need to use a sanitizer rinse just prior to milking in order to keep bacteria counts low. Summer humidity and heat, which can contribute to bacterial growth and prevent dairy equipment from drying properly between uses, may also necessitate the use of a sanitizer rinse just prior to milking. Additionally, some states (such as Vermont) require that a sanitizer be used on milking equipment just prior to milking.

Studies have shown that when sanitizers are used in greater-than recommended amounts, there can be unhealthy levels of sanitizer residues and by-products in the milk. Therefore, care needs to be taken to ensure that no more than the proper amount of sanitizer is used.

If bleach is used as a no-rinse sanitizer, by federal regulations it needs to be used at a ratio of no more than 1 Tablespoon of bleach per gallon of water (assuming the bleach has a content of 5.25% sodium hypochlorite). Alternatively, chlorine test strips can be used to verify that the chlorine concentration is correct. Be aware that some bleaches (such as Clorox Disinfecting Bleach) have a higher concentration of sodium hypochlorite and therefore need to be used in smaller amounts.

Test to Verify That Cleaning Process is Working Well

Every farm is unique, so there is no one cleaning process that will work in all cases. For instance, complex milk pipeline systems require different cleaning processes than simple bucket milker systems. Coliform Count and Standard Plate Count (SPC) tests can be used as verification tools to determine whether the cleaning process is working properly.

Ideally, these tests should be performed at least once a month, or more frequently such as weekly or daily. These tests can be performed inexpensively and conveniently with the use of an on-farm lab. (The Raw Milk Institute is still offering grants to offset the costs for on-farm lab materials to farmers who are completing our free Listing program.)

Testing more often allows farmers to identify trends and trouble spots. Whenever the cleaning processes or equipment are being changed, coliform and SPC testing can be performed to ensure that the new processes and equipment have been optimized for low-risk raw milk.

Daily Cleaning Habits for Success

Once you’ve optimized your cleaning processes and verified that they work well through bacterial testing, you can settle in to creating the daily cleaning habits that will keep your milk production running smoothly. You may also find that the shelf-life of your milk has increased and that the flavor is even better.

If you need help optimizing your cleaning processes for low-risk raw milk, contact us for free mentoring.