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From Cow to Carton! By Ella Salter
Transcript of From Cow to Carton! By Ella Salter
How Cows turn Grass into Milk
Cows, like other animals such as goats, sheep, giraffes and camels belong to a group of animals called Ruminants. Being in this group means that cows have four different stomach compartments that each play different roles in digesting food and making milk. To produce milk, cows need to eat a variety of grasses, clover and bulky fodder, plus food that is rich in protein and energy.
Journey through the Four Stomachs
The cow half-chews the grass in her mouth then she swallows it, bringing it to her first stomach, the Rumen. This stomach can hold about 100 litres of chewed grass. The grass then mixes with water and is broken down with stomach juices and microbes. The grass then enters the second stomach which is called the Reticulum, where it is softened and turned into small lumps called cuds. Each cud then returns to the cow's mouth where it is chewed for 40 to 60 times for about a minute. The chewed cud is swallowed, this time traveling to the Omasum, where it's pressed to remove water and broken down further. The cud then makes it's way to the fourth stomach (the Abomasum) and is finally digested. Next, the digested grass passes through the small intestine, where all the essential nutrients the cow needs is absorbed.
The Rest of the Process
through the Cow
It takes 50 to 70 hours in total for a cow to turn grass into milk. One cow can make between 25 and 40 litres of milk per day, depending on the breed. The nutrients that comes from the grass is turned into milk by four mammary glands in the udder. The milk is then released from the udder through the teat with the the exception of when the cow is feeling uncomfortable or stressed. Suction from either a calf or a milking machine helps draw out the milk. To stop milk from flowing through the teat it contains a muscle called a sphincter. For each litre of milk a cow produces, more than400 litres of blood has to travel around the udder to deliver nutrients and water frothe making of the milk. A cow only has approximately 45 litres of blood in her body, Therefor blood must be continuously flowing around her udder to help with the milk production.
Milking lines are attached to the four teats of a dairy cow using suction cups. These lines are attached to milking machine which use pumps to gently drain the milk from the udders of the cow. Cows are normally milked at least twice a day with milking time taking about five minutes per cow depending on the type of machine and the amount of milk the cow is producing. Most dairies have enough machines to milk more than 20 cows at one time.
The milk then travels through the milking lines to stainless steel pipes. These pipes lead to refrigerated storage tanks (or vats) which quickly cools the milk to 4 degrees celsius.
Before being loaded into the trucks tanks the tankers first test the milk's quality and freshness. Trucks which have big refrigerated tanks made of stainless steel on the back of them take the milk to the plant. These tanks keep the milk cold and clean to drink during the time that they are being transported.
At the Plant
From Cow to Carton!
By Ella Salter
Before a cow can start producing milk, she (all diary cows are females) has to have delivered a calf. A cow only starts to produce milk when her first calf has been delivered which is usually when they are around two years of age. For her next calves she continues to make milk for the first seven months of her pregnancy. The farmer stops milking the cow two months prior to the birth, leaving the cow to devote all her energy to giving birth to her calf.
End Product =
Once tanker drivers have driven the milk to the processing plan, before it can be transferred, each load is tested for antibiotic residues. If the milk shows no evidence of antibiotics, it is then pumped into the plant's holding tanks for further processing. If the milk does not pass the test then the entire truck load of milk is discarded and the farm samples are tested to find the source of the antibiotic residues. Positive test results are extremely rare and account for far less than 1% of the tank loads of milk delivered to procession plants. Milk at the plant is stored at less than 7°C and is usually processed within 24 hours, but can be held for up to 72 hours for processing. It has to be done at these times because the longer the milk is held the more likely that spoilage organisms that grow at refrigerated temperatures called psychotrophs will start growth.
During this process the milk is gently heated then cooled to make sure that the milk contains no germs. This is done witha machine called the pasteurisation machine. The conditions of this heating treatment used fro pasteurisation depends on the final product. Lower temperatures are used for refrigerated products and higher temperatures are used for products stored at room temperature.
Homogenisation is usually a two step process with the first stage pushing milk through small, narrow tubes or pores. As the diameter shrinks whith the flow of milk remaining constant, pressure builds up and fat globules break apart. The higher the pressure, the smaller the particles become. Some of the smaller fat globules begin to reassemble and because this is the the tendency for these new, chemically altered globules step two of this process breaks up this unwanted cluster and makes sure everything stays in thin liquid.
After homogenisation the milk is again stored and kept cold, ready for packaging. The milk then travels through pipes to automatic packaging machines that fill and seal the milk into cartons or bottles. As the now packaged milk moves through the line, a use-by date is printed on each of them to show how long the milk will stay fresh.
Storage and Packaging
To and In the Stores
The milk is stored in huge cool-rooms before being taken to shops and supermakets where it is sold to the consumers.
Raw milk is a mixture of milk-fat globules, various solids and water. Over time, the fat globules separate out and rise to the surface as a layer of cream, leaving what is essentially skim milk, down below. This is how consumers got their milk before the homogenisation machine and many found it inconvenient as the milk wounld have to be regularly stirred. With the milk naturally seperating like this it was also harder to sell meaning less money for the farmers. What the homogenisation machine does is it seperates the particles that rise to the top called fat globules making them the same size and density through the two step process which has already been mentioned. This machine has helped farmers to develope milk and consumers to be happy with the final product.