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From safety standpoint, milk poses many challenges
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Monday, 01 October, 2018, 08 : 00 AM [IST]
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Nidhi Shukla Zaveri
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The definition of milk
Milk is defined as whole, fresh, clean, lacteal secretions obtained by the complete milking of healthy dairy animals such as cow, buffalo, goat, sheep, and camel. It is a good source of many vitamins and minerals which are essential for the maintenance of good health. The composition of milk is influenced by several factors such as species, breed, genetics, age, nutrition, season, lactation stage, completeness of milking, diseases and environmental conditions.
Since ancient times, milk is considered as a versatile commodity. It is consumed by all the age groups of every religion, in all the seasons, rural and urban inhabitants of the world. Even in history, milk and milk products have been staples of the diets of young and old around.
To begin with, milk contains “nine essential” nutrients that include proteins, fats, carbohydrates, vitamins, minerals, which are required to live a healthy sustainable life, generate energy, promote growth and development of an individual. Thus, these requirements make it one of the most nutritious beverages one can enjoy.
But from a food safety standpoint, milk poses many challenges. Milk is an excellent growth medium for a variety of both pathogenic and non-pathogenic microorganisms. To overcome these challenges, strict adherence to prescribed procedures based on comprehensive risk analysis is critical.
Food safety
Hygienic milk handling includes using clean equipment, maintaining a sanitary milking environment, observing good personal hygiene, preserving the quality of milk during storage and transportation.
Milk is used to prepare many valuable dairy products including cheese, butter, cream, yoghurt, butter oil, ice cream, which are widely consumed by people of developed as well as developing nations.
Milk contamination
Milk can be contaminated by physical (hair, dirt, plastic, stone, dung, broken glass, and wooden splinter), chemical (cleansing agents, insecticides, antibiotics, radionuclides, fungicides) and biological agents (bacteria, viruses, protozoa).
The contamination can occur at any stage of milk chain during production, processing, packaging, and distribution.
The milk can be contaminated with microbes during or after milking. Quality milk should have longer keeping quality, proper nutritive value, normal taste, colour, and odour and be free from extraneous matter. According to the World Health Organization (WHO), food safety can be defined as the assurance that food will not cause any harm to the consumer when it is eaten according to its intended use. The milk secreted from an uninfected animal’s udder is considered sterile, but later it becomes contaminated during milking, cooling and storage.
Microbial composition and contamination
Most common bacteria causing mastitis in dairy animals are Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, Escherichia coli and Corynebacterium pyogenes. The infections of mammary gland, unclean udder and teats of animal also lead to increase in bacterial count of milk.
Further, the risks of contamination from milk handlers are definitely higher, when cows are hand-milked in comparison to when they are machine-milked. Soiled clothes and hands of handler also increase the risk of contamination of milk and milking equipment many folds.
The milk handlers with infected wounds on hands contribute pathogenic Streptococcus spp., Staphylococcus spp. and micrococci. Improperly cleaned milk cans and lids if left moist will result in multiplication of thermophilic bacteria. Water used in productions should be of good bacteriological quality. Inadequately cleaned storage tanks, untreated water supplies from natural sources like borewells, tanks and rivers may also be contaminated with the faecal microbes, such as Coliforms, Streptococci and Clostridia.
Some of the practices that increase aerial counts in milk are sweeping of floors just before milking process, brushing of animals prior to milking process, having the dusty bedding materials for animals and allowing dust and dirt to accumulate on the walls or ceiling of sheds.
Precautions to be taken
Use of potable water, proper handling, storage and transportation of milk.
Milk must be cooled to a temperature below 50 degree by using refrigerators or water coolers preferably within two hours after milking.
The milking should be completed as quickly as possible in about 5-8 minutes.
The first milk should be examined for Mastitis test for the presence of mastitis every time prior to milking. If the dairy animal is suspected for mastitis, the particular quarter should not be milked and treated.
The animal should be fed with nutritious and complete feed, which consists of roughages and concentrate mixtures. The feed, fodder and silage should be procured from a reliable source and should be stored properly.
Ample supply of clean water should be made available at dairy farms for various activities
High quality of raw milk can be produced from healthy animals, which are kept under good hygienic conditions.
The foremilk should be discarded in a proper place. Cleaning is the process of removing the soil from the surfaces of equipment and utensils used in the dairy industry.
A number of detergents or sanitisers such as chlorine, idophore, benzal conium chloride, sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium phosphate, sodium meta silicate, citric acid, phosphoric acid, tartaric acid, nitric acid are used for cleaning dairy equipment. Chlorine is the most commonly used sanitising agent in the food industry including dairy industry.
If milk handler is suffering from communicable disease such as a sore throat, bacillary dysentery, tuberculosis, typhoid, diphtheria or having open wounds and pustules, they should not be allowed to work in dairy plant. It is recommended that persons working in the dairy industry should undergo a periodical medical examination to rule out any infectious disease.
Hygienic milk production, proper handling and storage of milk and appropriate heat treatment can reduce or eliminate pathogens in milk. In many countries, milk processing factories are required a law to ensure pasteurised milk before selling it to the public.
Many consumers also routinely boil milk before drinking it to protect themselves from milk-borne diseases. Processed milk must be handled hygienically to avoid post-processing contamination.
Global milk production
Globally, there are over 264 million dairy cows, which produce around 600 million tonne of milk each year. The total milk production from cows, buffaloes, goats, sheep, and camels is estimated around 703,996,079 tonne annually.
It is emphasised that food safety measures such as good hygienic practice (GHP), good manufacturing practice (GMP), hazard analysis and critical control points (HACCP), quality management, microbial risk assessment should be implemented in all food industries, including dairy sector.
In summary, dairy product manufacturers have many food safety issues and opportunities that are unique within the food industry. Strict regulations, the potential for bacterial and allergenic issues, ingredient concerns and the need for heightened surveillance of suppliers provide constant challenges. Yet, with all these challenges, the US dairy supply remains one of the world’s safest.
(The author is a freelance writer. She can be contacted at nidhishukla67@yahoo.in)
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