Milk and dairy products can be source of food borne illness as the quality can be affected by various means such as biological, chemical, or physical agent. Such hazards may be introduced into the dairy chain at any time during primary production, milking, formulation and processing, packaging, and labelling, transportation, storage, preparation, and serving. Since milk contains a large amount of water and nutrients therefore it is at a higher risk of experiencing various hazards in the process and being spoilt making its shelf life short.
General food safety hazard is broadly categorized into
- Physical Hazard
- Chemical Hazard
- Microbiological Hazard
Occurrence of such hazard in milk can be in farm level and in industry level including during receiving, processing and during storage of product. In this article we shall be looking in brief the incidents of hazards.
We shall be looking stepwise, the involved process and chances of hazard in each step that can spoil the quality of milk, in farm and in processing industry.
- Milking the cows:
Process- The process may be manual (by human hands) or mechanical that involves the use of certain automatic machines, attached to the cows’ udders, which collect the milk from its body.
Incident of Hazard- The animal feces coming into direct contact with the milk, infection of the udder, cow diseases, like bovine tuberculosis ,bacteria living on the skin of animals, environment for example, feces, dirt, and processing equipment, insects, rodents, and other animal vectors, cross-contamination from dairy workers, such as contact with dirty clothing or boots. Excessive use of hormones like oxytocin, veterinary drugs to induce lactation for increased milk production in cows and its harvest can contaminate the milk.
2. Collection and storage of milk:
Process- In farm, milk is collected in milk cans, which are then transported, to the industry or to the local customers with storage at temperatures less than 4℃.
During transportation, storage, handling of milk to avoid any bacterial or microbiological growth.
Incident of Hazard- Due to insufficient milk storage equipment, temperatures of the surroundings, insufficient transport facilities etc. milk can get spoiled and leads to wastage of the whole batch of milk. Fluctuating temperatures and humidity, surrounding atmospheres affect the quality of milk. Moisture entering milk cans while transportation or storage, will destroy the quality of milk and spoil it.
To achieve profit by selling substandard quality product, samples are found with chemical substances like added detergents, urea, skim milk powder, starch, sugars, vegetable fats, neutralizer etc., which has strong harmful effect.
3. Milk Processing In milk and dairy product manufacturing plant-
Process- Milk received in dairy processing plant is sent to pasteurizing vats where milk is pasteurized either through HTST (high temperature, short time) or through LTLT (low temperature, long time) or by UHT (ultra-high temperature) etc. HTST involves heating at the sample at 72℃ for 15 seconds, LTLT involves heating the sample at 68℃ for 13 minutes, UHT involves heating the sample at 130℃ for 5 seconds and then suddenly cooling to lower temperatures to kill/inactivate microorganisms, thus increasing its shelf life.
Incident of Hazard– Milk contain harmful microorganisms such as Salmonella, Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, Yersinia enterocolitica, Bacillus cereus, Clostridium botulinum, Mycobacterium bovis, Brucella abortus and Brucella melitensis. Coxiella burnetii present in milk, the most heat-resistant organism is of public health significance. There are high chances of improper microbial inactivation if pasteurization parameter not followed correctly.
4. Pasteurized Milk Packing:
Process-The pasteurized milk is packaged into milk pouches, tetra packs or glass/plastic bottles, which are then sent for delivery to the customer.
Incident of Hazard- Foreign particles such as broken pieces of glass or tiny metals, pose a positive risk and hard objects impurities occur in milk when not processed and passed through screening and micro filtration process can become cause of physical hazard.
- Cleaning of processing equipment’s-
Process- Cleaning of processing and accessory equipment after and before manufacturing process by water (hot or ambient temperature), cleaning agents and chemicals (Acid and Lye) etc. to remove residue of products from pipelines and equipment’s.
Incident of Hazard- Presence of cleaning agents, disinfectants in the milk might occur from improperly cleaned storage tanks. Various kinds of chemicals can also enter either intentionally or unintentionally from water which is used for cleaning and.
There is the need to deliberately put in place systems to ensure the safety of milk and dairy products to prevent any detrimental health and economic impact. To minimize the health risks associated with the consumption of milk and dairy products, all food-chain operators, including dairy farmers, processors, distributors, retailers and consumers would need to take the required steps to maintain food-safety. Governments and regulatory agencies have a crucial role to establish controls and standards, including inspection and surveillance to ensure effective controls and conditions for safe production, transportation and storage of milk and dairy products. The outcome of all these would be a well-functioning dairy system that brings economic incentives protects the health of the consumers.