Student Pack
What is Milk?
Dairy milk is produced by a cow for feeding her calf and, because of its nourishing benefits, it has been part of the human diet for thousands of years.
Why is Milk so Good For You?
Unprocessed milk, fresh from the cow, will separate itself into two parts after a few minutes - it will separate into a layer of cream and a layer of non-fat skim milk.
The cream is actually the natural milk fat which has floated to the surface because it is lighter.
But milk is much more complex than that.
Milk is mostly water, approximately 87 per cent, and if you removed all the water you’d be left with what is called the solid component. This is made up of milk fat (cream), a natural milk sugar (lactose) and milk protein together with vitamins and minerals - and all of these elements can vary depending on the type of cow the milk came from, what the cow has been eating and the time of year.
Milk fat (also known as butterfat) - this is present in milk in the form of small globules which differ in size, number and composition depending on the breed of cattle which produced the milk.
The average proportion of fat in milk is 3.7 per cent, which makes milk a healthy low-fat product. Some Jersey and Guernsey cows produce milk with a higher fat content, often exceeding 5 per cent, which makes the milk taste richer and creamier. In milk approximately 60 per cent of milk fat is saturated fat and 40 per cent unsaturated.
Milk fat contains more than 200 different fatty acids, which are believed to give the cream and butter its taste.
Two of these fatty acids are ‘essential fatty acids’ which the body cannot produce itself; therefore we have to ingest them in what we eat.
These two acids, Linoleic and Arachidonic acids, are very important in controlling bio-chemical functions such as heart and blood circulation and in the way the body uses its fat stores.
Milk fat also contains vitamins A, D, E and K (although vitamins D, E and K are not in significant levels).
Protein - milk also contains 3.4 per cent protein on average. Protein is made up of building blocks called amino acids which are important to the body. They are used to maintain your blood, skin, hair and fingernails.
There are essential amino acids just like there are essential fatty acids (see above). These cannot be made by the body and have to be supplied by our food. Milk is often called the ‘complete food’ because it contains a surplus of all eight essential amino acids for adults.
These are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine and two additional amino acids for young children, histidine and arginine.
Milk sugar (also known as lactose) - is a compound of two basic carbohydrates: glucose and galactose. Lactose is only found in milk and compared to sucrose (normal sugar) it is one sixth as sweet and far less soluble. Lactose is digested by the enzyme lactase which is formed naturally by the body.
When this compound is broken down, lactic acid is formed in the intestines and this stimulates the absorption of calcium, phosphorous and other minerals. This may also help to balance out the growth of less desirable organisms and increase growth of some beneficial strains of bacteria.
If the enzyme lactase is absent, the undigested lactose passes through the intestine to the large bowel. Natural bacteria then ferment the lactose, producing acid and gas which may cause abdominal pain, bloating or diarrhoea. This is generally what being ‘lactose intolerant’ refers to, although true lactose intolerance is much rarer than generally thought.
Calcium - is a key mineral and is found in high quantities of milk. It is not only needed for skeletal growth and maintenance, but it also assists in:
- the contraction of muscle fibres
- blood coagulation for wound healing
- nerve impulses
- activation of enzymes (which help control the body’s metabolism).
Thus it is very important to maintain an adequate supply of calcium throughout your adult life as well as doing some form of weight bearing exercise to prevent brittle bones.
Phosphorous - another important mineral found in milk and is linked with calcium. The ratio of phosphorous to calcium is important in order to maximise the absorption of calcium. Phosphorous also plays a vital role in the body’s biochemical reactions.
Types of Milk
Milk is generally grouped into categories according to the way it is processed.
White drinking milk can be separated into two main categories:
1: Fresh milk - heat-treated at not less than 72ºC for no less than 15-20 seconds.
2: Ultra Heat Treated (UHT) - processed at 146ºC for 3-4 seconds.
All milk on sale to the public has been heat treated to some extent. This is a critical step as it ensures that all harmful bacteria (called pathogens) are destroyed.
There are no preservatives in milk and its shelf life is controlled by a combination of heat treatment, being refrigerated at less than 4°C, and being packaged in an airtight container.
If milk is exposed to any kind of light it may cause a breakdown of the components and the milk may develop a slightly ‘off’ flavour.
‘Fresh’ milk has a shelf life of 10-14 days from manufacture and must be refrigerated at all times. As a consumer, it is important to ensure that the milk is never out of the fridge for very long and should be used within four days after opening, to maintain its freshness. It is always best to store milk at the top back shelf of the fridge, as this is often the coolest spot. The best conditions for handling and storing milk are to keep it where it’s cool and dark.
‘UHT’ milk has the same composition as fresh milk but it has been sterilised by ‘flash’ heating usually above 140ºC for 3-4 seconds. It is then cooled to room temperature and packaged under sterile conditions with a special film called polyethylene. The packaging contains several layers of film to block out any ultraviolet light and an airtight seal (generally foil) to keep out bacteria.
Both fresh milk and UHT milk are available in a range of different types. These have been developed to suit people’s varying needs.
Whole milk - also called Full Cream Milk contains at least 3.2 per cent milk fat and at least 3.0 per cent protein. The milk can vary depending on the type of cow and what the cow has been eating. Therefore different batches of whole milk are often blended together to create a uniform consistency.
Skim milk - is milk with the cream removed and has a fat content of less than 0.15 per cent.
Flavoured milk - has been flavoured and sweetened, using natural or artificial products. Dairy Farmers manufactures full fat flavoured milk and also reduced fat flavoured milk.
Dairy Farmers’ Range of Milks
Dairy Farmers manufactures a wide variety of white milks with different nutritional highlights so consumers are able to choose the milk which suits them best.
Surf the product section of our website to see the range of products we have.
Dairy Farmers also has a range of convenient, natural, long life milks. These are great for storing in the cupboard to prevent those annoying times when people run out of fresh milk, or for use when fresh milk isn’t suitable, such as camping or boating.
