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Biotechnology Unit 1 : Dairy Industries i. Milk ii. Yoghurt iii. Cheese iv. Environmental Impact i. Milk Milk is an important food for most British people. – PowerPoint PPT presentation

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Title: Biotechnology

  • Unit 1 Dairy Industries
  • i. Milk
  • ii. Yoghurt
  • iii. Cheese
  • iv. Environmental Impact

i. Milk
  • Milk is an important food for most British
  • It is an important part of a balanced diet
  • Milk contains
  • fat
  • starch
  • sugar
  • protein
  • minerals

Milk treatment
All milk comes from dairy cows. It is treated in
different ways to produce different types. Milk
is available in forms such as
pasteurised skimmed UHT (ultra high
temperature) powder
Heat treatment of milk
  • Milk is an ideal place for bacteria to grow.
  • Some bacteria are harmful so all milk is heat
    treated to kill them.
  • Common methods of heat treating are by
  • pasteurisation
  • Ultra High Temperature

  • Most milk is treated by pasteurisation.
  • Method
  • 1. Heat milk to 72ºC for 15 seconds.
  • 2. Cool quickly to below 10ºC.
  • 3. Pack in bottle, carton or container.
  • Pasteurised milk will keep for up to
  • five days in a fridge.

Ultra High Temperature
  • UHT milk is heated to a higher temperature than
    pasteurised milk.
  • UHT milk is heated to 135oC-142oC for 2-5
  • This process alters the taste of milk.

Resazurin Test
  • Resazurin dye is a chemical that changes colour
    in response to the number of bacteria in a
  • Can be used to tell us if milk is fit to drink.

Colour of sample Bacterial content Drinking quality of milk
Blue-purple Very low Good
mauve low Satisfactory
pink medium Poor
white high unsatisfactory
Experiment resazurin test
5 day old milk resazurin
Fresh milk resazurin
10 day old milk resazurin
Time (min) Fresh milk 5 day-old milk 10 day-old milk
Fat content of milk
Milk can be graded by its fat content
Type of milk Fat removed
Whole milk none
Semi-skimmed half
skimmed almost all
Evaporated milk has ½ the water removed and is
used like cream.
Content of milk (continued)
  • Removing fat from milk reduces vitamin content
    e.g. Vitamin A
  • Skimmed and semi-skimmed milk have fat removed so
    the vitamin content is reduced.
  • Young children should be given whole milk which
    has more vitamins.

ii. Yoghurt
  • Milk can be preserved (made to last longer) by
    changing it into yoghurt or cheese.
  • Natural yoghurt can be used as starter cultures
    to make yoghurt in the lab.

Making Yoghurt
  • Starter cultures contain special bacteria that
    make lactic acid from the sugar (lactose) in the
  • lactose lactic acid
  • (sugar in milk) (thickens and gives taste)
  • Lactic acid thickens the milk and gives the
    yoghurt its taste.

Making yoghurt Method
  1. Heat milk to 43oC (helps bacteria grow)
  2. Add 1 teaspoon of starter culture (natural
  3. Cover with cling film.
  4. Incubate yoghurt at 43oC for 7 hours.
  5. When ready, place yoghurt in fridge for 4 hours.

Types of Yoghurt
  • There are different methods for making yoghurts
  • Stirred yoghurts bacteria is added to the
    batch. It is then put in to pots when ready.
  • Set yoghurts bacteria is added then the
    mixture is put straight into the pots where it

Aseptic conditions
  • Air contains many types of microbe.
  • Many are also present in dust as tiny clumps
    called spores.
  • During experiments, certain precautions should be
    taken to create sterile (aseptic) conditions.

  • This is done for two reasons
  • To stop unwanted microbes getting into the
    experiment and spoiling it
  • To stop ant microbes used in the experiment

  • 1. Hands should be washed, cuts should be
  • 2. Work surfaces should be disenfected.
  • 3. Lab coats should be worn
  • 4. All equipment should be sterilised in an
    autoclave (heated to 121C for 20 mins).

iii. Cheese
  • Making Cheese
  • Milk is pasteurised to kill most bacteria.
  • Special bacteria are added to convert milk sugar
    (lactose) into lactic acid.
  • Enzymes (rennet) are added to clot the proteins
    in milk to form solid cheese.

Types of rennet
Milk clotting enzymes (rennet) can come from
different sources.
Type of rennet Source Advantage Disadvantage
Calf rennet calves Original source, used for centuries. Animals must be killed, risk of disease
Fungal rennet fungus Cheap, large amounts, OK for vegetarians. taste
GM yeast rennet yeast No animals involved, OK for vegetarian, same as animal rennet. Public concern about genetically modified foods
iv.Environmental ImpactMonitoring Waste
  • Cheese making uses the enzyme rennet which makes
    the milk proteins clot to form curd.
  • The liquid left is called whey.

milk rennet curds (solid) whey
(liquid) cheese waste product
Whey and pollution
  • Whey contains sugar. What would happen if whey
    was released into rivers?
  • 1. Bacteria would use the whey sugars as food
    and reproduce.
  • 2. As the number of bacteria increased it would
    use up the oxygen so oxygen levels would decrease
    in the water.
  • 3. Fish and other living organisms would start
    to die as the oxygen level decreased.

Pollution prevention
  • To prevent pollution whey can be-
  • a. treated before release
  • b. upgraded (used for something else)

Treatment of whey
  • Add bacteria which feed on whey and turn it into
    carbon dioxide and water.
  • Remove bacteria and release cleaner water into
  • Test water oxygen level to make sure it is OK.

Upgrading whey
  • Waste whey used as food for growing some types of
  • In the right conditions these yeast strains
    produce alcohol from the sugars in the whey.
  • Alcohol produced is creamy (found in Baileys
    Irish Cream)

Preventing pollution
  • Yeast Industries
  • i. Bread
  • ii. Beer
  • iii. Fermented milk drinks
  • iv. Flavouring and
  • food colouring
  • v. Environmental impact

i. Bread
  • Yeast
  • a single-cell fungus (plant)
  • used in bread-making for 1000s of years
  • is added to flour to make bread rise (dried or
    fresh yeast activity 2.1)

Yeast (continued)
  • Yeast is a living organism.
  • It respires to release carbon dioxide.
  • It is the carbon dioxide that makes bread rise.

Growing yeast
  • Huge numbers of pure yeast can be grown in large
    vessels called fermenters.
  • This yeast can be used in the baking or brewing
    industry to make bread or beer.
  • Cultures of pure yeast can be grown on an agar

ii. Beer
  • Beer is an alcoholic drink made from
  • water
  • barley
  • sugar
  • hops
  • yeast

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The role of yeast in making beer
  • sugar alcohol carbon dioxide
  • energy
  • Yeast uses sugar to release energy.
  • During this process, called fermentation,
    alcohol and carbon dioxide are released.
  • The gas carbon dioxide is what makes the beer

Ales and lagers
  • Different strains of yeast give different ales
    and lagers.
  • These yeasts use the sugars at different rates
    and at different temperatures.

Ale and lager yeasts
Type of yeast Growth temp Time to grow Position of yeast in vessel
Ale 12-18ºC 6 days Rise to top
Lager 8-12ºC 21 days Sink to bottom
Making beer
  • There are over 1200 different brands of beer in
    Britain each with its own flavour.
  • Around half the beer is lager, the rest is
    bitter, ale and stout.
  • Different beers are brewed in different ways and
    have different alcohol contents.
  • Traditional beers have around 4 alcohol
  • (activity 2.3)

Alcohol contents of beer (Activity 2.4)
Drink Alcohol Content
Barley ale
Low alcohol beer
Alcohol free beer
Alcohol contents of beer (Activity 2.4)
Drink Alcohol Content
Lager 4
Barley ale 11
Low alcohol beer 1
Alcohol free beer 0.05
Wine 12
Vodka 40
Whiskey 40
Maturing the beer
  • Beer must be matured before it
  • can be drunk.
  • Maturing beer
  • Improves flavour
  • Removes any solids
  • Gives sparkle
  • (activity 2.6)

  • Beer can be
  • cask conditioned
  • (often called real ale)
  • brewery conditioned
  • (kegs, bottle, cans)

Cask conditioned beer
  • Cask conditioned beer is put into casks (huge
    containers made
  • from wood or steel)
  • Sugar is added to the cask.
  • Yeast still producing carbon dioxide which makes
    the beer sparkle.
  • Beer produced is dark with a strong flavour.

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Brewery conditioned beer
  • Stored in large tanks
  • Sold in kegs,
  • bottles or cans.
  • Remains of yeast and other solids removed.
  • Beer (e.g.) lager is clear and bright.
  • Long shelf life (keeps for a long time)

Differences cask conditioned and brewery
conditioned beers
(Activity 2.6) Cask conditioned beer Brewery conditioned beer
Example of type of beer produced
Storage conditions
Description of beer
Differences cask conditioned and brewery
conditioned beers
(Activity 2.6) Cask conditioned beer Brewery conditioned beer
Example of type of beer produced Real ale e.g. Lager Keg beers Bottles/cans
Storage conditions Casks Sugar added Yeast present Large tanks Yeast removed
Description of beer Dark colour High flavour Clear/bright Lasts longer
iii. Fermented Milk Drinks
  • In many countries it is difficult to keep milk
    and yoghurt fresh.
  • The milk can be fermented slightly to make it
  • Yeast is used to turn the sugars in milk into

Making fermented milk drinks (activity 2.7/2.8)
  • Kefir is a refreshing, fizzy, slightly alcoholic,
    yoghurt drink.
  • This drink can be made by a method called

Making Kefir
  • Step 1
  • Sodium alginate lactase (enzyme that
    breaks down lactose)
  • Add wine yeast
  • Add calcium chloride
  • drop by drop
  • (hardens beads)
  • Immobilised beads

  • Step 2 Warm milk
  • Add live yoghurt
  • Add Immobilised beads
  • Leave at 43ºC for 5 hours
  • Filter mixture to give
  • fermented milk drink

Beads can be re-used
  • Immobilisation can be used to trap an enzyme and
    some yeast into a jelly bead.
  • Advantages
  • After the reaction the beads can be washed and
  • Saves money (enzymes are expensive)
  • Bead easily separated from product (e.g. by

jelly coat
yeast enzyme
iv. Food flavouring
  • Yeast can be used for
  • Making bread
  • Alcoholic drinks
  • Flavouring food
  • Foods with yeast flavouring
  • Meat flavoured crisps e.g. chicken,bacon
  • Oxo cubes
  • Marmite
  • (activity 2.9)

Food colourings (activity 2.10)
  • Wild salmon and trout have pink flesh.
  • This colour comes from
  • the pink coloured prawns
  • and shrimps they eat.
  • Farmed salmon would have grey flesh but they are
    fed red dye just before they are killed which
    makes their flesh pink.

Red dye
  • Feeding dye doesnt affect the
  • flavour but makes their
  • flesh more appealing to eat.
  • Now red yeast can be fed to the fish. This gives
    a pink colour to their flesh.

Red yeast
v. Environmental Impact
  • Waste from yeast industries should not be dumped
    in rivers.
  • Yeast would act as food for bacteria which would
    cause pollution.

Getting rid of waste
  • Waste can be
  • upgraded and
  • used for animal
  • feed.
  • Treated water should
  • be tested before
  • releasing into rivers.

The methylene blue test
  • We are going to test some water samples to see
    if they could be put into a river.
  • Collect samples A, B and C
  • 3specimen tubeslids
  • 3 labels
  • dropper
  • measuring cylinder
  • methylene blue dye

Testing water samples for pollution The
Methylene Blue Test
Time Colour change Water condition Pollution scale
2-3 days
4-5 days
4-5 days
The methylene blue test
Time Colour change Water condition Pollution scale
Immediate Blue to clear Dangerous for river Very polluted
2-3 days Blue to clear Dangerous for river Very polluted
4-5 days Blue to clear Needs more treatment Slightly polluted
4-5 days Still blue Safe for release Not polluted
  • Detergent Industries

Enzymes in washing powders
  • The word detergent means something that cleans
  • soaps
  • washing up liquid
  • washing powder

Biological washing powders
  • Biological washing powders contain enzymes.
  • Enzymes are chemicals that improve the way in
    which the powder cleans.

What is biological washing powder made of?
  • Biological washing powder is made up of
  • 1 enzymes
  • 99 water softeners
  • bleach
  • other chemicals (to help water get into the

Where do the enzymesin washing powder come from?
  • Bacteria are tiny organisms found almost
    everywhere on Earth.
  • Scientists found bacteria that were harmless and
    produced enzymes that could be used in washing
  • Large numbers of these bacteria grow (cultured)
    very quickly in huge industrial fermenters that
    give the best conditions for growth.
  • Enzymes produced are then separated from the
    bacteria and used to make biological washing

The use of enzymes in washing powders
  • Enzymes in washing powders digest the stains on
    clothes like enzymes in the gut digest food.
  • Different enzymes digest different stains.
  • Fat digesting enzymes digest fatty stains.
  • Starch digesting enzymes digest fatty stains.
  • Enzymes make up a small part of powder
  • but a large part of the cleaning power!

Activity 3.1 To show how an enzyme can remove a
  • Stains from food like eggs contain protein.
  • Photographic film has protein on its surface.
  • In the following experiment, enzymes like those
    in biological washing powder are used to remove
    the stain on a piece of photographic film

Protein stain
Expt. To investigate the effect of enzymes on a
protein stain
  • Method
  • Collect 2 test tubes.
  • Label test tubes A and B
  • Add 1 piece of film to each test tube.
  • Half fill tube A with enzyme
  • Half fill tube B with water
  • Shake each tube
  • Put tubes in water bath at 50oC for 30 mins
    shake tubes every 5 mins
  • Remove film, dry and examine.

Tube contents Protein digested?
Film Enzyme
Film water
Comparing biological and non-biological washing
  • Biological washing powders contain enzymes.
  • Non-biological washing powders do not contain
  • This experiment compares the ability of these two
    types of washing powder to remove different stains

Comparing bio and non-bio washing powders
Warm water bio powder
Warm water non- bio powder
Stained cloth
Stained cloth
Stain Removed with bio powder? Removed with non-bio powder?

Disadvantage of biological washing powders
  • Original biological washing powders sometimes
    caused an allergic reaction in some people.
  • This caused skin rashes, eczema and asthma.
  • New powders are now produced with enzymes
    enclosed in a harmless waxy coating.
  • This helps to prevent allergic reactions.
  • (Activity 3.3)

Advantages of biological washing powders
(Activity 3.4)
  • Adding enzymes to biological washing powders
    means cleaner clothes (stains are digested).
  • 2. Work best at low temperatures 40oC - 55oC
    (temperatures above 60oC destroy enzymes) so need
    to heat clothes to high temperatures to get them
    clean-saves energy and money.
  • 3. Lower temperature used with biological washing
    powders reduce damage to delicate fabrics.

Environmental Impact Monitoring Waste
  • Making detergent uses energy for
  • Production
  • Packaging
  • Transporting
  • But most energy is used in the home for
  • The wash cycle
  • Tumble drying
  • Ironing

Detergents and energy Activity 3.5
  • To provide all the energy
  • needed power stations burn
  • coal, oil or gas.
  • This gives off carbon dioxide
  • and sulphur dioxide that
  • pollute the atmosphere.
  • Low temperature wash less energy good for
    public and environment!!

  • One manufacturer of detergents has set targets
    for waste management
  • Reduce weight and volume of packing
  • Use reusable materials
  • Encourage recycling programmes
  • Encourage safe disposal practises
  • New Micro powders and liquids use less
    packaging and powder for each wash.

Detergents and the Environment (Activity 3.6)
  • Detergents are flushed away as waste water and
    can pollute the environment.
  • Detergents can be toxic
  • (poisonous) to wildlife.
  • Manufacturers test products to check they wont
    harm fish or other living organisms in rivers.

  • Detergents containing phosphates and sulphates
    pollute river
  • Tiny plants (algae) reproduce quickly to form
  • Algae die
  • Bacteria feed on dead algae
  • Number of bacteria increases
  • Bacteria use up oxygen in water
  • Fish and animals die

Reducing Environmental Impact
  • Detergents in water tested at sewage works in
    mini sewage plants
  • Sewage plants could remove the phosphates and
    sulphates to reduce environmental impact
  • Using low phosphate detergents can also reduce
    environmental impact

Washing clothes in other countries (Activity
  • Most people in the world
  • wash clothes by hand
  • Washing machines in other countries are different
    from those in the UK
  • In the USA washing machines
  • are bigger and use more water
  • In Japan and Taiwan washing machines do not heat
    the water. Clothes are pre-soaked and washed more

  • Unit 4 Pharmaceutical Industries
  • i. Antibiotics
  • ii. Antifungals

  • discovered in London in 1928 by Alexander
    Fleming (Scottish scientist)
  • He was growing bacteria on agar plates to
  • One of his plates had been contaminated with
    a fungal spore and he noticed no bacteria would
    grow near it
  • He found out that fungi produce chemicals to
    stop growth of competing bacteria

  • These chemicals are called antibiotics
  • The antibiotic Fleming had discovered was
    penicillin and had been produced by the fungi
  • Different types of antibiotics kill different
    bacteria but not viruses like those causing flu
    or the cold.

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  • Other scientists developed ways of extracting
    peniciliin fron the fungus and purifying it
  • The first man to be treated with penicillin was a
  • He was ill from blood poisoning and not expected
    to live more than a few hours.
  • When injected with penicillin there was a huge
    improvement in his condition.
  • The man only died when the antibiotic ran out
    after ten days.

  • Different types of antibiotics kill different
    bacteria but not viruses like those causing flu
    or the cold.
  • Penicillin now cures diseases such as pneumonia
    and diptheria

Antibiotic action
  • If an antibiotic can inhibit growth of a species
    of bacteria we say the bacteria is sensitive to
    that antibiotic
  • If an antibiotic has no effect we say that
    species of bacteria is resistant to the
  • There is no one antibiotic that works against all
    species of bacteria

Antibiotic Pneumonia Tuberculosis Typhoid Diptheria
penicillin - -
Streptomycin - - -
Tetracycline -
Cloram-phenical -
very effective effective
slightly effective - no
  • Different antibiotics have different methods of
    destroying bacteria
  • Some destroy bacterial cell walls
  • Some burst the cell membrane
  • Some interfere with the bacterial cells chemical

Different types of antibiotics (Activity 4.3)
  • Different antibiotics are effective against
    different infections.

Antibiotic Infection which it treats
penicillin respiratory infections (and many others)
aminoglycosides Eye and skin infections
fluoroquiniles Gonorrhoea (STD)
cephalosporinc Urinary infections
tetracyclines acne
Choosing the correct antibiotic
  • When a patient has an unknown bacterial
    infection, a sample of body fluid taken so that
    the bacteria can be grown on nutrient agar.
  • A multidisc is placed on the agar surface.

  • It is important to have a choice of antibiotics
  • The person may be allergic to an antibiotic
  • Bacteria may become resistant to an antibiotic

Antibiotic production
  • Antibiotics produced in large fermenters holding
    200,00 litres
  • Growth conditions are controlled by computer to
    provide correct
  • Temperature
  • pH
  • Oxygen concentrations
  • Food supply
  • Sterile conditions
  • Antibiotic purified by filtering
  • and solvent extraction

Genetic modification
  • Genetic modification is a new technology.
  • It changes the genes found in living things.
  • The penicillin gene can be taken from the fungus
    and put into bacteria.
  • These genetically modified bacteria can then
    produce very large quantities of penicillin.
  • New, more effective antibiotics can also be
    produced to help fight disease.

Antibiotic production
  • Activity 4.2
  • Antibiotics were first produced in ___________ by
    ______________ ____________. They are chemicals
    which kill ____________. They do not kill
  • Antibiotics are produced in huge ____________.
    Growth conditions inside the fermenters are
    controlled by ____________. If the glucose level
    in the vessel falls then the ________ will detect
    this _____________and more ____________ will be
    added. The antibiotic is _________________ by
    filtering and _______________ extraction.
  • ______________ modification is a new
    ______________ which can alter the _____________
    of living organisms. This new technology may be
    used to produce new _____________ which will be
    better at fighting_________

Antibiotic production
  • Activity 4.2
  • Antibiotics were first produced in London by
    Alexander Fleming. They are chemicals which kill
    bacteria. They do not kill viruses.
  • Antibiotics are produced in huge fermenters.
    Growth conditions inside the fermenters are
    controlled by computers. If the glucose level in
    the vessel falls then the computer will detect
    this change and more glucose will be added. The
    antibiotic is purified by filtering and solvent
  • Genetic modification is a new technology which
    can alter the genes of living organisms. This new
    technology may be used to produce new antibiotics
    which will be better at fighting disease.

Antibiotic resistance
  • Some infections have become resistant to
    antibiotics. This means that the antibiotic is no
    longer effective.
  • Staphylococcus aureus is a bacteria that causes
    abscesses and boils
  • 1940s this bacterium was sensitive to penicillin
    so it could be used to treat Staphylococcus
    aureus infections.

  • Now some strains of this bacteria are resistant
    to penicillin and it is no longer effective.
  • These strains have also become resistant to other
    antibiotics and are known as MRSA. These strains
    are prevalent in hospitals where infections are
    easily spread.
  • This has happened because because antibiotics
    have been over-used.

Public concern
  • People are concerned about the over-use of
    antibiotics in agriculture and by vets.
  • The same antibiotics are
  • used in animals and humans.
  • It is thought that this might result in more
    resistant strains of bacteria.
  • New antibiotics to which bacteria are not
    resistant are continually being looked for.

  • Some infections are caused by microbes called
  • They are spread from person to person by tiny
    groups of fungi called spores.
  • Drugs used to treat these infections are called
  • Anti-fungal treatment slows down or stops fungal

Athletes foot
  • This fungi likes to grow areas of the skin which
    are warm and moist and get little fresh air.
  • Forms an itchy rash between the toes.
  • Transferred in shared dressing areas or showers.
  • Flakes of skin from an infected person are enough
    to pass the infection on
  • Treated with antifungal creams or powders.

Oral thrush
  • Fungal infection of the mouth.
  • Seen as white spots in the mouth.
  • Common amoung
  • Babies
  • People with ill fitting dentures
  • Chemotherapy patients
  • Drug users
  • Treated with antifungal mouth washes or pastilles

  • Begins as a patch of itchy skin
  • Spreads to form spiral shapes
  • Caused by a fungus not a worm!