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For more information, please contact our Dairy Hygiene Specialists: John Bewes on 07917 753147 or john.bewes@molevalleyfarmers.com and |
Low bactoscans don’t necessarily mean clean milk
The production of quality raw milk is under scrutiny yet again as more focus is being placed on producing milk with low Thermoduric levels.
Thermoduric bacteria are increasingly becoming an issue in raw milk supplies and if they are not removed at the end of milking by an effective cleaning routine they will stay in the plant to multiply in large numbers and be swept away into the bulk tank at the next milking.
Thermoduric are organisms which have developed mechanisms to resist heat treatment and can survive in small numbers during milk processing to become spoilage organisms in finished products such as cheese, yogurt and fresh milk.
Although Thermoduric bacteria may not be of particular concern to the dairy farmer, their presence can have an influence on the Bactoscan results if present in large enough numbers and therefore should not be dismissed simply as a processing issue.
In raw milk, Thermoduric organisms originate from sources in the cows environment such as soil, fodder, silage, dust and the cows coat. These organisms can grow readily on poorly cleaned and sanitised milking equipment.
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High levels above 500cfu/ml are a good indicator of poor milking plant or bulk tank cleaning. Common faults with cleaning are:
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Inadequate volumes of water at each stage of the wash
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Poor water temperatures and profiles during the hot wash
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Poor choice or under dosing of chemical
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Poor flow and turbulence of water (mechanical action)
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Failure to include a terminal disinfection in the final rinse
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Inadequate milk stone removal treatment particularly in hard water areas
Parlour hygiene should not be thought of as a standalone task, but as part of a total hygiene management system encompassing pre-milking hygiene, udder hygiene and bulk tank cleaning as well as cleaning the parlour itself. It is only by operating a managed system that optimum hygiene can be achieved across the milking process.
With this in mind it should be remembered that it is also possible and should not be overlooked, that some Thermoduric organisms can be derived from the cows teats and gain access to the raw milk supply through inadequate teat preparation. The use of a pre milking teat disinfectant to reduce bacteria on the teat skin followed by thorough removal with individual paper towels or cloths will produce the best and most consistent results.
Where high Bactoscan issues are being experienced it is worth considering a bulk tank bacteriology sample which will highlight organisms of concern and potential solutions, depending on the numbers and combinations of bacterial groups found.
An effective routine depends on four factors – chemical choice and concentration, temperature, time and the physical action of the water. These factors work in combination with one another and if any of them are compromised then the routine will not be fully effective.
Modern dairy chemicals are designed to work at a specific concentration. Reducing this concentration by over-diluting the chemical means that there is less active ingredient in circulation and this will reduce the effectiveness of bacterial kill and deposit removal.
Reducing the time the chemical circulates will have the same effect, as the total exposure of the plant to the chemical is reduced. But leaving chemicals circulating too long is also a problem.
Temperature is an essential element in the effective melting of fat deposits and the removal of Thermoduric bacteria that could otherwise survive heat treatment. The aim should be to circulate the chemicals at a temperature of at least 65°C for 3 minutes.
While it is tempting to leave the circulation cleaning running while other jobs are carried out there is a real risk that it will be left running too long and that water temperature will drop too low to maintain the suspension of deposits in solution, thus re-depositing them back into the parlour.
The final key element in an effective cleaning routine is water turbulence. The swirling action of the water plays a critical role in the removal of deposits, especially in the claw and milk meters.
With the current focus on maximising milk bonuses and controlling costs, the time spent reviewing the effectiveness of the parlour cleaning routine can be time well spent as it could increase milk price and save money.
Alison Cox, Field Technical Specialist, JohnsonDiversey
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