Milk

Milk is a white liquid produced by the mammary glands of mammals. Milk is an emulsion or colloid of butterfat globules within a water-based fluid that contains dissolved carbohydrates and protein aggregates with minerals.

Because it is produced as a food source for a neonate, all of its contents provide benefits to the growing baby mammal. It is the primary source of nutrition for young mammals before they are able to digest other types of food.

Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many diseases in the baby.

Milk contains:

Enzymes : The enzymes of cow's milk are reported as proteinases, lactase, diastase, lipase, salolase, catalase, peroxidase, and aldehydrase.

Vitamins : All the vitamins recognized at the present time are contained in milk. Some are present in comparatively large and others in smaller amounts.

Pigments : The appearance of milk is white. This is due to light rays reflected by the colloidally dispersed constituents of the milk, the calcium caseinate, and calcium phosphate.

Salts : Milk contains salts of potassium, sodium, magnesium, calcium, phosphates, chlorides, and citrates. Traces of sulfates and carbonates are found. Iron is present in small amount. Iodides are also found in small amounts. The salts of milk are found in milk in solution, in the colloidal state, and in combination with the proteins. Calcium and magnesium are in combination with the casein to form calcium and magnesium caseinates. Zoller states that there may be traces of sodium and potassium caseinates.

Lactose : Sugar

Fat : Butter fat is composed of glycerol and fatty acids. Fatty acids of both the saturated and unsaturated series are present. The relative percentage of the unsaturated fatty acids varies with the feed, averaging higher in summer than in winter.

Apart from above milk also contains : 

• Niflumic acid -  anti-inflammatory painkiller
• Mefenamic acid – anti-inflammatory
• Flunixin -  anti-inflammatory
• Ibuprofen – painkiller
• Diclofenac – anti-inflammatory
• Ketoprofen -  anti-inflammatory
• Florfenicol –  antibiotic
• 17B-estradiol – sex hormone
• Triclosan – anti-fungal drug
• Pryimethamine – anti-malaria drug
• 17a-ethinylestradiol – steroid hormon

SO how the milk contamination occurs?

Read Carefully…

Sources of Microbial Contamination :

ÖBefore the cow is even milked, pathogens in the surrounding environment can    get into the cow's feed or water. Bacteria on the inside or outside of     the cow's udder can get into the milk. If the milking device (human or mechanical) hasn't been properly sanitized it may contaminate the raw milk

ÖStorage and Transfer of Raw Milk: Any time the milk is transferred or stored; all equipment and containers must be sterile to prevent contamination. The storage temperature must be low enough (usually 4 degrees Celsius) to keep any bacteria remaining in the milk from growing.

ÖPasteurization: We know that pasteurization doesn't kill all the bacteria in milk, but it won't even kill the ones it's supposed to if the guidelines for time and temperature aren't met. One way the dairy industry checks milk to make sure it has been properly pasteurized is by testing for alkaline phosphates. This enzyme has the same D-value as the tuberculosis bacterium, so if it's found in pasteurized milk, that means that time and temperature requirements were not met.

ÖEquipment: Postpasteurization contamination (PPC) because of flaws in equipment or poor sanitation practices is the most common reason for pasteurization failures.Equipment has to be properly maintained and tested, and cleaned and sterilized between uses.

ÖThe plate heat exchanger is one potential source of PPC, since cold raw milk and hot pasteurized milk pass each other on opposite sides of the heat exchange plates. If the plates have leaks or cracks, the raw milk can contaminate the pasteurized milk.

ÖStorage and Transfer After Pasteurization: Milk is vulnerable to what the industry calls time-temperature abuse whenever the milk is transferred or stored. This includes all points at or between the processing plant, the warehouse, the store and your home. The weak link in the overall cold chain is usually that indeterminate period after the milk leaves the retail outlet and reaches the consumer's refrigerator.

ÖNow that it's been brought to your attention, the pressure is on to get the milk home and into the fridge as quickly as possible. Check the temperature of your refrigerator regularly, too. It should always be less than 10 degrees Celsius.

Sources of Chemical Contaminants :

The sources of chemical contaminants in raw materials of animal origin, mainly milk, are to a large extent comparable to those of raw materials originating from plants. The most of chemical contaminants in milk and dairy products are veterinary drugs such as antimicrobials (antibiotics and sulfonamides), hormones, anthelminthitic drugs, pesticides and etc.

ANTIBIOTIC DRUGS

Much of the veterinary treatment of dairy cattle involves intra mammary infusion of antibiotics to control mastitis. Drugs apply to control several illnesses and to increase milk production. The most commonly used antimicrobials in dairy cattle can group into five major classes. These include the beta-lactams (e.g, penicillins and cephalosporins), tetracyclines (e.g., Oxytetracycline, tetracycline and chlortetracycline), amino glycosides (e.g., streptomycine, neomycin and gentamycin), macrolides (e.g., erythromycin) and sulfanomides (e.g., sulfamethazines). These drugs are administered to animals by many routes such as injection routs, orally in the food and water, topically on the skin and by intra mammary and intrauterine infusions. Whenever any route with an antibiotic treats a lactating cow, measurable levels of the antibiotic are usually detectable in the milk for a few days after the last.

BOVINE GROWTH HORMONE

Bovine Growth Hormone (BGH) or Bovine Somatotropin (BST) is a genetically engineered protein hormone either identical or similar to the natural bovine pituitary product. Its primary function is to increase milk production dairy lactating cattle. Therefore, BST is a protein hormone that increases milk production in cows between 10 and 15% An increase in milk yield typically occurs with 5 days after beginning of treatment. BGH increases activity and/or longevity of mammary secretary cells, probably via Insulin-like Growth Factor (IGF)-I produced by the liver and/or the mammary gland.

 PARASITICIDE DRUGS

Parasiticide drugs also use to remove internal parasites such as flukes, tapeworms (helminths) and nematodes (round worms) are important in animal production systems. These metabolites can account for all residues found in milk and dairy products at any time point that are both bioavailable and of toxicological significance.  Residues of benzimidazole compounds can occur in milk and dairy products and it is necessary to observe withdrawal periods for milk after therapy. Toxicological studies of animals have shown albendazole and its metabolites to be mutagenic.

PESTICIDES AND INSECTICIDES

Contamination of feeds arises in the field or store where treatment with pesticides occurs. Chlorinated pesticides and related compounds such as DDT, Polychlorinated biphenyls (PCBs) and Dioxins can enter milk and dairy products. The chlorinated hydrocarbons are extremely durable, persistent, endocrine-disrupting activities, bio-accumulating and widely distributed toxic compounds that find their way into the food chain usually through use in controlling environmental or animal pests As much as 20% of an ingested chlorinated hydrocarbon excretes in milk. Chlorinated hydrocarbons adhere to milk fat and butter contains a much higher proportion of these insecticides.  DDT can accumulate in fatty tissues and can transfer into milk and dairy products. Organochlorine pesticides such as DDT and Hexachlorocyclohexane (HCH) have banned in most countries since 1983. Residues of such compounds may persist in the environment and cause contamination through the food chain . Presented organochlorine pesticide residues (owing to their use in sanitary actions) indicating a human exposure through milk and dairy products.

MYCOTOXINS

Some of the moulds produce various toxic metabolites under appropriate temperature and moisture conditions. These metabolites, which may be hazardous for human health, are called mycotoxins  Aflatoxin M1 (AFM1) may be found in the milk of animals that are fed with Aflatoxin B1 (AFB1) containing feed. It can produce by moulds of feeds that have been harvested damp, have not adequately dried, or are improperly stored. These substances through the feedstuff can infect dairy cattle. The content of AFM1 in milk is entirely dependent on the presence of the precursor AFB1 in the ration of dairy cattle and it can numerically express as feed to milk ratio. The forming of AFM1, metabolite of AFB1, occurs in liver and it secrets into milk in the mammary gland of dairy cows.  

HEAVY METALS

Heavy metals can enter to milk and dairy products and affect the health of people who have consumed contaminate milk and dairy products. There are various levels of heavy metals in produced milk samples of different country.

Recombinant Bovine Growth Hormone and Cancer

According to the American Cancer Society recombinant bovine growth hormone (RBGH) is just one of the synthetic (man-made) hormones that are marketed to dairy farmers to increase milk production in cows. Think about this for a moment. If this particular growth hormone increases milk production in cows than what will it do to the human body over time?

• RBGH contains amplified levels of the hormone IGF-1, which promotes cancer tumors in the breast, colon, and prostate.
• It contains increased somatic cell counts (SCC’s), which means the milk has more pus, which makes it turn sour more. quickly.
• Hormone use makes the cows produce low quality milk during times when they should not be giving milk, in other words, during a cows rest period.

· a new study which concludes that milk from cows injected with recombinant Bovine Growth Hormone (rBGH) increases risks of breast and colon cancers in humans. This study is published in the January issue of the International Journal of Health Services, a peer-reviewed, leading international public health journal.

· The study summarizes evidence that rBGH increases levels of insulin-like growth factor (IGF-1) in milk. IGF-1 is a powerful stimulator and regulator of cell-growth and division in humans and cows. The study concludes that increased IGF-1 levels are risk factors for breast and colon cancer.