Milk is an opaque white liquid produced by the mammary glands of female mammals. It provides the primary source of nutrition for newborns before they are able to digest other types of food. The early lactation milk is known as colostrum, and carries the mother's antibodies to the baby. It can reduce the risk of many diseases in the baby. The exact components of raw milk varies by species, but it contains significant amounts of saturated fat, protein and calcium as well as vitamin C.
Varieties of milk
There are many different varieties of milk available for consumption within the UK.
The different milks tend to vary according to the way they are produced, and in their fat content.
Which milks are available?
Natural whole milk is milk with nothing added or removed.
Whole standardised milk is whole milk standardised to a minimum fat content of 3.5%.
Some EU member states may produce an additional category of whole milk with a minimum fat content of 4%.
Whole homogenised milk is identical in fat and nutrient content to whole milk or whole standardised milk however it has undergone a specific process known as “homogenisation” which breaks up the fat globules in the milk. This spreads the fat evenly throughout the milk and prevents a creamy layer forming at the top.
How is it produced?
Natural whole milk is collected from the dairy herd and undergoes various processing techniques before it reaches the shelf for consumption by the general public.
Most of the milk consumed in Europe, Scandanavia, the USA, Australia and New Zealand is pasteurised.
Pasteurisation is the process whereby milk is heated with the purpose of killing potentially harmful micro-organisms such as certain pathogenic bacteria, yeasts and moulds which may be present in the milk after initial collection. This helps to protect against any food bourne illness that can occur through consumption of raw (unpasteurised) milk.
Following pasteurisation, the milk is rapidly cooled and is then stored in a refrigerator in order to preserve its shelf life.
Various different pasteurisation and heat treatment techniques can be used in the production of milk which can affect storage capacity-detailed in later sections.
Much of the milk in the market is now homogenised as well as pasteurised. Homogenisation offers a way to reduce the fatty sensation of whole milk and prevent the formation of a cream plug.
Semi skimmed milk
Semi skimmed milk is the most popular type of milk in the UK with a fat content of 1.7%, compared to 4% in whole milk and 0.3% in skimmed milk -see nutritional composition of milks
Skimmed milk has a fat content of between 0.1-0.3 %. Skimmed milk therefore has nearly all the fat removed.
It contains slightly more calcium than whole milk and lower levels of fat soluble vitamins, particularly vitamin A, as this is lost when the fat is removed-see nutritional composition of milks
The lower level of fat in skimmed milk reduces its calorie (energy) content. For this reason it is not recommended for children under the age of 5 years as they need the extra energy for growth. However it is ideal for adults who wish to limit their fat or calorie intake.
Skimmed milk has a slightly more watery appearance than other types of milk and has a less creamy taste due to the removal of fat.
Organic milk comes from cows that have been grazed on pasture that has no chemical fertilisers, pesticides or agrochemicals used on it.
The producers must register with an approved organic body and are subject to regular inspection.
Once the cows have been milked, the milk is treated in exactly the same way as regular pasteurised milk.
The nutritional content of organic milk is exactly the same as non-organic milk.
Jersey and Guernsey milk
Channel Island milk is produced from Jersey or Guernsey breeds of cow and has a particularly rich and creamy taste.
It tends to be slightly higher in calories and fat than regular whole milk and also has a higher content of fat soluble vitamins -particularly vitamin A which is important for the promotion and maintenance of healthy growth and development -see nutritional composition of milks
Jersey and Guernsey milks tend to have a visible cream line and are commonly found in supermarkets as “breakfast milk”.
The flavoured milk market is one of the fastest growing dairy sectors.
There are a wide variety of flavours and consistencies to cater for all ages and tastes with a choice of long-life (i.e. Ultra Heat Treated or sterilised) or fresh flavoured milk.
Most flavoured milk products are produced using reduced fat milk varieties and usually have a fat content of around 1%.
The most popular flavours are chocolate, strawberry and banana however more sophisticated flavours such as peach, mocha or products made with real Belgian and Swiss chocolate have been developed for the more adult market.
In comparison with plain milks, flavoured milks tend to have slightly higher sugar content, however studies have suggested that they are still a favourable option for children and teenagers as they provide a wide range of beneficial nutrients and are less likely to cause damage to teeth than sugary foods and drinks.
Interestingly, recent studies have suggested that chocolate flavoured milk can be used as an effective recovery aid after intense bouts of exercise.