What is clean milk?
Clean milk is generally defined as milk drawn from the udder of healthy animals, which is collected in clean dry milking pails and free from extraneous matters like dust, dirt, flies, hay and free from pathogenic bacteria.
Clean milk has a normal composition, possesses a natural milk flavor with low bacterial count and is safe for human consumption.
Clean milk has longer shelf life and keeping quality, transported to longer distance, high commercial value and helps to produce good quality dairy products. It also gives protection against diseases like typhoid, dysentery, diphtheria, septic sore throat etc. to the consumers.
Sources of milk contamination
The main sources of bacterial contamination of milk are the udder and flanks, milker, milking environment, milking equipment and vessels used for milk storage and transportation.
The animal itself and the milking environment act as contaminants of particulate matters like dirt, dust and dung etc. Therefore reduction of contamination at source level will render clean milk production and will be beneficial for the producers, manufacturers and consumers.
Steps for clean milk production
Milk from healthy udder is always relatively free from harmful bacteria and on the other hand, milk from infected udder contains high bacteria count that reduces the shelf life and keeping quality of milk. In dairy husbandry practices, animal management involves mainly feeding, housing and health of animal.
- Feed ingredients should be stored in moisture-free conditions otherwise there are chances of fungal contamination.
- Feed and fodder should be free from industrial and environmental contaminants, pesticides, insecticides, fungicides, fumigants, pathogenic agents, aflatoxin as well as heavy metals.
- Dry fodder like good quality hay or straw should be given to the cows during lean period and supply adequate amount of minerals and vitamins that will fulfill the deficiency.
- Animal should be fed one hour before milking so that the contamination from feed should be avoided and at the time of milking, non-dusty concentrate can be provided to keep animals busy.
- Silage and wet crop residues should not be fed at milking place as it may impart foul odor to the milk.
- Animal shed is the main source of contamination from dairy husbandry practices.
- A good shed protects against micro-organisms as it keeps out other animals, people, wind, rain and excessive heat, all increasing the danger of contamination.
- Mud, urine, feces and feed residues should be regularly removed from the shed. There should be proper drainage, sufficient ventilation and lighting facilities.
- In very wet areas, slaked lime may be used for drying of floor surface.
- Sufficient water facility should be available for drinking as well as washing the shed, animal, utensils and milker’s hands etc.
- The animal shed should be well-roofed, well ventilated, dry and comfortable with adequate elevation in conventional housing or if loose housing the floor should be clean and dry.
- There should be appropriate arrangement for disposal of animal waste and left over feed and fodder.
- The milking parlor should be free from flies and insects which are potential sources of contamination, and piggery and poultry farming should be avoided near the dairy animal premises.
- Herd should be routinely examined for bovine contagious diseases like Foot & Mouth Disease, Tuberculosis, Johne’s Disease, Brucellosis, mastitis, etc.
- The diseased or sero-positive animals should be kept in isolation.
- Sanitary precautions like cleaning and disinfection of animal sheds to prevent and control diseases should be adopted.
- Regular check for udder wounds and mastitis should be done during milking.
- Vaccination of animals against FMD, Anthrax, etc. should be done regularly.
- The skin of the animal provides a large surface for possible contamination. Long hair on the flanks, hind legs, tail and udder should be clipped at frequent intervals.
- If washing of animals is not practiced regularly as is observed in most cases, at least grooming of the animals should be done to keep the hair and dust away from milk.
- The udder is the part of the animal needs more attention to be washed before and after each milking, and dried with a clean cloth or towel.
Cleanliness of milking equipment and utensils
- The common milking equipment like milking pails, milking machine, milk cans, milk pipeline recorder, bulk, strainer, chiller, bulk tank and storage tank etc. are used starting from milking to storage.
- Dirty milking equipment is one of the main sources of infection of milk as residual milk in utensil helps in growth of microorganisms.
- Proper cleaning of utensils before and after milking removes germs and dirt from the utensils.
- About 15 minutes before milking, milking equipment should be rinsed with a sanitizing solution to remove dust and contamination.
- Milking equipment should also be thoroughly cleaned after use because any milk residues in the equipment will allow microorganisms to grow rapidly.
- The utensils and equipment used during milking should be of standard quality. They should be made up of acceptable, non-absorbent, corrosion-resistant material and should be easy to clean.
- The utensils and equipment should not have any joints or open seams and should be free from rust.
- The milking utensils and equipment should be thoroughly cleaned and sanitized after each milking. An acceptable, non-toxic and non-corrosive cleaning and bactericidal agent should be used for cleaning and sanitation, and use of ash or mud not recommended.
- After cleaning and sanitation, the utensils and equipment should be stored in such a manner and location to prevent contamination from flies, insects, dust, dirt, rodents etc.
- They should preferably be stored in an inverted position off the ground to facilitate drainage of wash water.
- Milking pail should have dome shaped top to prevent contamination of milk from outside during milking.
- Microorganisms may enter to milk during hand milking and machine milking.
- In case of hand milking, the extent of contamination coming from the milker is higher as compared to machine milking.
- The milker should therefore be free from contagious diseases.
- Nails should be well trimmed, should wear clean clothes and should wash hands with soap and water before milking, then dry with a clean towel.
- Floor sweeping just before milking, feeding roughage at the time of milking should be avoided.
- If the calves are suckling, the calf should be allowed to suckle at the beginning of the milking.
- The udders and teats should be washed and massaged for at least 30 seconds and dried prior to milking.
- Fore-stripping should be collected in separate utensil/cup for examination and abnormal milk should be discarded to avoid flies and insects.
- The fore-milk should not be allowed to run on the floor as this increases the danger of contamination.
- The milk should be drawn directly into the pail as fast as possible and milking should be completed within 6-8 minutes.
- The milker should not wipe their hands on the body of the animals or on their own body.
- After milking, the teats can be dipped or sprayed with a gentle antiseptic solution like potassium permanganate, iodine solution etc.
- The milking area should be thoroughly cleaned after each milking.
- Milk should be strained using a clean cloth or a strainer and the cloth should be washed and dried daily.
Storage, transport and cooling
- Milk should be cooled as soon as possible to a temp below 5 °C in a refrigerator to preserve its keeping quality. The sooner the milk is cooled after removal, the better is the quality.
- Cool milk immediately as bacterial growth is retarded by cooling the milk within 2 hours of milking.
- Before storage, it is best to filter the milk with a clean cloth in order to remove large particles that might have entered the milk. The cloth should be thoroughly cleaned after use and left to dry in the sun.
- If chilling is not feasible, preservatives like lactoperoxidase can be added to prolong the time before the milk gets spoiled.
- Milk should be stored in clean containers with a lid and kept in a cool and shady place where the danger of contamination is minimal.
- Milk should be transported in clean containers, transport time should be kept to an absolute minimum and violent movement of the milk should be avoided as milk fat can soon turn rancid in the presence of oxygen.
- Though today our country stands second to none in case of milk production but very meager amount of milk is termed as clean milk in India.
- In contrast, the island country New Zealand is producing the highest amount of clean milk and has highest contribution in global clean milk exports.
- We are denied global access to milk exports only because low hygiene of milk produced in the country.
- If we want to tap the global export potential in dairy sector, we have to focus on clean husbandry practices for producing clean milk in the country.
- The Government of India has launched Strengthening Infrastructure for Quality & Clean Milk Production Programme way back in 2003 which has suitably increased the production of clean milk in the country but still the access to programme by small and marginal farmers is to be enhanced.
- There is a need of strong and potent capacity building in the sector for effective dissemination of knowledge related to clean milk among small and marginal farmers residing in numerous hamlets in the country.
Dr. Renu Chauhan
Veterinary Officer, CVH, Dadahu,
Department of Animal Husbandry, Government of Himachal Pradesh
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