If you have bought raw milk then you are not new to its unsavoury smell. This smell is characteristic in nature and you can trace it back to a certain brand of soap, a known deodorant spray, some farm chemical spray or characteristic body odour of someone you know. You are right in your weird thinking; yes, milk is a smell magnet and will hold onto any smell in its environ with amazing ease.
This peculiar characteristic calls for special treatment to ensure quality and wholesome milk production. The process of clean milk production begins with the cow, its residence, through its feed to the person milking and how milk is handled thereafter. Anything going wrong at any of these stages can impart a foreign smell to milk.
Clean milk has a natural flavour and is safe for human consumption. Quality and wholesome milk has a longer shelf life and can be converted into other quality milk products like yoghurt, butter or cheese.
Clean milk also minimises spread of diseases like brucellosis, tuberculosis and diphtheria to humans. Milk is rich in nutrients and will offer favourable conditions for bacterial, fungal and mold growth.
Bacterial count is a measure of milk quality and is determined by the cleanliness of milk, temperature at which it was stored and the age of milk.
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Bacteria have enzymes that digest milk and alter its composition. To avoid microbial growth store milk at very low temperatures (below 40 Celsius) at all times. If your cow lives in a dirty environment with cow dung and flies everywhere don’t be surprised when the milk picks the cow dung smell.
When the teats get soiled with cow dung apart from being at risk of mastitis infection if not well cleaned at milking this can easily contaminate the milk and give it a “dungy” smell.
Housing
A well designed cow shade should have a gradually sloping drainage to ensure dung is washed away in a pit located some safe distance from the cow.
The milking shade should be cleaned before and after milking with clean water and disinfectant. Avoid using disinfectants with strong smells as that too can be picked by the milk. If you are using generators in your farm locate them far away and don’t store fossil fuel anywhere near a milking cow.
The milker
Where hand milking is practised the person doing the milking can easily impart undesired smell into milk. To avoid this, first he or she must be very clean; while a white laboratory coat is recommended during milking it is not a guarantee of cleanliness.
Before milking ensure your body is clean and free from any strong smell either from the bath soap, body creams or sprays. Cut short your nails and thoroughly wash your hands before milking.
There are peculiar milking habits employed by milkers which easily contaminate milk with bad smell. Some milkers will use the calf saliva or dip their fingers into milk or water to reduce friction between their fingers and the cow teat.
These practices are employed where poor milking technique of pulling rather than squeezing is used. Pulling the teats will result in wound that can further act as a source of milk contamination.
Udder cleanliness
The udder must be washed thoroughly with lukewarm water then wiped dry with a clean towel before milking. Milk from a cow suffering from mastitis will not only have unpleasant smell but will also have flakes or milk clots. To avoid this screen for mastitis by passing the first milk strips from every quarter through a strip cup.
If mastitis is detected don’t mix milk from the affected cow or quarter with the rest. Immediately after milking, dip the teats in disinfectant to prevent entry of disease causing micro-organisms from climbing up the udder.
Feeds?
Animal feeds with a strong smell shouldn’t be fed in large quantities to lactating animals. The most notorious of this is fishmeal, cabbages, garlic, onion and tuber plants. High grain diets have been shown to interfere with milk composition greatly reducing it shelf live.
Storage of milk immediately after milking
Aluminum and stainless steel milk cans should be used to store and transport milk due to their ease of cleaning and their ability to prevent contamination. Never use plastic jerricans to store and transport milk. Containers initially used to store detergents, disinfectants should never be used to store milk; you will be surprised at how milk will resurrect that smell you thought had been cleaned off the container. Heat treatment if not well done can give milk bad flavour as it alters its chemical and physical composition.
Some milk off-tastes
Acid flavour which gives a sour or tingling sensation on tongue is likely due to lactic acid accumulation in milk due to bacterial multiplication.
This flavour is a result of poor refrigeration of the milk at higher temperatures that cause bacterial contamination. Cowy or cow’s breath flavour results from poor housing conditions, dirty udder, poor ventilation and can also be due to diseases like ketosis.
The gases eructed by the cow in poor ventilated shades will linger around and can get into milk giving it a cowy flavour.
Milk will have a salty taste if the cow is in late lactation stages or is suffering from mastitis.
If you get this taste immediately do a mastitis test on all the cows and quarters. To avoid these off-flavours farmers must set and observe strict on-farm milk hygiene standards and sensitise the other farm workers on the importance of clean milk production.
Milk with a flat flavour is indicative of low solid content in milk and is a result of milk adulteration by addition of water or “old” milk.
- The writer is a veterinary surgeon and works as a Communication Officer for the Kenya Tsetse and Trypanosomiasis Eradication Council (KENTTEC)
