industrial chemistry (milk report)

1. Milk

2. What is milk?
 Milk is a white liquid produced by
the mammary glands of mammals. 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.

3. What is milk?
 Milk derived from cattle species is an
important food with many nutrients.
The precise nutrient composition of raw
milk vary by species and by a number
of other factors, but it contains
significant amounts of saturated
fat, protein and calcium as well
as vitamin C. Cow's milk has
a pH ranging from 6.4 to 6.8, making it
slightly acidic.

4. History of milk

5. History
 In 1856, Gail Borden received the first
United States and English patents for
condensed milk. Gail Borden patented a
method for making condensed milk by
heating it in a partial vacuum. In
1861, Gail Borden opened a condensed
milk plant and cannery in Wassaic, New
York.

6. History
 In 1863, Louis Pasteur invented
pasteurization, a method of killing harmful
bacteria in beverage and food products. In
1891, the first U.S. milk processing plant to
install pasteurization equipment was the
Sheffield Farms Dairy in Bloomfield, New
Jersey. They used a German-made
pasteurizer. In 1908, Chicago became the
first major American city to pass a law
requiring commercial milk to be pasteurized
milk.

7. History
 In 1878, Doctor Gustav De Laval invented the
continuous centrifugal cream separator.
 In 1884, Doctor Hervey Thatcher of
Potsdam, New York invented the first glass
milk bottle called Thatcher's Common Sense
Milk Jar, which was sealed with a waxed paper
disk.
 Victor Farris was the inventor of the paper milk
carton. In 1932, plastic-coated paper milk
cartons were introduced commercially. In
1964, the all plastic milk container was
commercially introduced.

8. Sources of milk

9. Sources
 Aside from cattle, many kinds
of livestock provide milk used by humans
for dairy products. These animals include:
 Camel
 Donkey
 Goat
 Horse
 Reindeer
 Sheep
 Water Buffalo (Carabao)
 Yak

10. Components of
milk

11. Components
 Lipids including phospholipids and also fatty acids
 Proteins
 Caseins - Special types of proteins found in milk that
are bound to each other by calcium and or
phosphorus ions.
 Carbohydrates including
lactose, glucose, galactose, and other
oligosaccharides.
 Vitamins
A, B6, B12, C, D, K, E, thiamine, niacin, biotin, riboflav
in, folates, and pantothenic acid
 Mineral Salt forms 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.

12. Types of milk

13. Which milk are available?
 Whole milk
 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%.
 Whole homogenised milk is identical in fat and
nutrient content to 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.

14. Which milk are available?
 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 a minimum of 3.5% in whole
standardised milk and 0.1% in skimmed milk.
 Skimmed milk
 Skimmed milk has a fat content of between 0-
0.5% and an average fat content of
0.1%. 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.

15. Which milk are available?
 1% fat milk
 The EU regulations for milk classification previously divided
milk into three categories defined by the fat content;
whole, semi-skimmed or skimmed. Prior to 2008, any milk
that contained a different fat content was defined as a „milk
drink‟.
 On the 1st of January 2008 new regulations came into force
to facilitate consumer choice. Now any milk with a fat
content other than those laid out can also be considered as
„milk‟, provided that its fat content is clearly indicated on
the packaging in the form of „….% fat‟. However, these
milks cannot be described as whole, semi-skimmed or
skimmed.
 Following this change in regulation 1% fat milk is now
offered to consumers who like the taste of semi-
skimmed, but want to enjoy milk with a lower fat content.

16. Which milk are available?
 Organic milk
 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.

17. Which milk are available?
 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.
 Jersey and Guernsey milks tend to have a
visible cream line and are commonly found in
supermarkets as “breakfast milk”.

18. Which milk are available?
 Flavoured 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.

19. Which milk are available?
 Heat treated milks
 Approximately 99% of milk sold in the UK is heat-
treated, to kill harmful bacteria and to improve its
shelf life.
 Sterilised milk
 Sterilised milk is available in whole, semi skimmed
and skimmed varieties. It goes through a more
severe form of heat treatment, which destroys
nearly all the bacteria in it.
 Firstly the milk is pre-heated to around 50oC, then
homogenised (see below for a brief outline of
homogenisation), after which it is poured into
glass bottles which are closed with an airtight
seal.

20. Which milk are available?
 UHT milk
 UHT or ultra heat treated milk is a form of milk that
has been heated to a temperature of at least 135ºC in
order to kill off any harmful micro-organisms (e.g.
harmful bacteria) which may be present in the milk.
The milk is then packaged into sterile containers.
 All milk that is available for sale to consumers through
supermarkets and milkmen must be pasteurised i.e.
heated to 71.7ºC in order to make it safe for
consumers and improve its shelf life. However UHT
milks have a longer shelf life as a result of the higher
temperatures to which they are heated and the
packaging used to store them.
 UHT milk is available in whole, semi skimmed and
skimmed varieties.

21. Which milk are available?
 Evaporated milk
 Evaporated milk is a concentrated, sterilised milk
product. It has a concentration twice that of standard
milk.
 The process of producing evaporated milk involves
standardising, heat treating and evaporating the milk
under reduced pressure, at temperatures between
60ºC and 65ºC.
 Condensed milk
 Condensed milk is concentrated in the same way as
evaporated milk, but with the addition of sugar.
 This product is not sterilised but is preserved by the
high concentration of sugar. It can be made from
whole milk, semi skimmed or skimmed milk.

22. Which milk are available?
 Untreated (raw) milk
 All milk sold via the supermarkets and milkmen
has to be heat-treated (pasteurised) to kill
harmful bacteria. However, untreated milk can be
bought direct form a limited number of farm
distributors in England and Wales.
 Filtered milks
 Filtered milk goes through an extra, fine filtration
system, which prevents souring bacteria from
passing through.
 The nutritional content of the milk is unaffected
but the shelf life is increased.
 The processes involved
include, microfiltration, ultrafiltration and
nanofiltration.

23. Which milk are available?
 Dried milk powder
 Milk powder is produced by evaporating the water
from the milk using heat. The milk is
homogenised, heat treated and pre-concentrated
before drying.
 There are a number of ways to produce dried milk
powder including spray drying and roller drying.
 In the most commonly used spray drying process, the
concentrated milk is introduced into a chamber
(usually as a fine mist) through which hot air is
circulating. The droplets of milk soon lose their water
and fall to the floor as fine powder.
 Skimmed milk powder can be mixed easily with water;
however whole milk isn‟t easily reconstituted due to its
higher fat content.

24. Industrial
processes
involving milk

25. Milk Processing
 Clarification – is the process of removing undesirable
foreign matter and bacteria from the milk.
 Separation – is the process of dividing the milk into its
component parts mainly skimmed milk, cream, and other
effluents for further individual processing and to
maximize product variety and yield, also determines
which process each would undergo.
 Standardization – is the industrial adjustment of milk or
cream fat content to a precisely specified or desired
value.
 Pasteurization – is the process of heating liquids or
foods to kill microorganisms (such as
Brucella, Campylobacter, E. coli
O157:H7, Listeria, Mycobacterium bovis, Salmonella, and
Yersinia) that can cause disease. It was developed by
Louis Pasteur in 1864.

26. Milk Processing
 Methods for Milk Pasteurization
 High Temperature Short Time Treatment. Milk is
pasteurized at 161 F for 15 seconds.
 Low Temperature Long Time Treatment. Milk is
pasteurized at 145 F for 30 minutes.
 Flash Pasteurization. This type of pasteurization, which
involves high temperature for 3 to 15 seconds followed by
cooling and packaging, is used for drink boxes and other
liquids that can be stored for long periods of time without
refrigeration.
 Ultrapasteurization. Heating milk or cream to 280 F for 2
seconds can extend the refrigerated shelf life of milk from
60 to 90 days.
 Ultra-High Temperature Pasteurization. Heating milk
to 280 to 302 F for 1 or 2 seconds followed by packaging in
airtight containers allows storage without refrigeration for
up to 90 days.

27. Milk Processing
 Homogenization – allows milk
manufacturers to combine the cream and milk
so that it does not separate. The main goal
behind milk homogenization is to reduce the
size of the fat molecules in milk because
smaller molecules tend to stay suspended in
the body of the liquid. Only large globules
float to the top.
 Fortification – is the process of introducing
additional vitamins and minerals to the milk to
improve product quality.

28. Milk Processing Diagram