Biotechnology
Microorganisms used in food
production
Yeast (fungus)
• Used to make bread, beer and wine in the
process of fermentation.
• Learning Intentions
– Understand biotechnology’s use of bacteria
• Success Criteria
• All can
– I can state 3 uses of yeast and describe yeast
– I can state the word equation for glucose fermentation
• Most Can
– I can describe and compare aerobic and anaerobic
respiration
– I can describe the manufacture of beer
– I can explain batch processing
– While discussing the need to malt barley I can give
ideal growing conditions for yeast.
Biotechnological Process
• This is a process in which living
cells are used to convert a raw
material into a useful substance.
Raw materials
Suitable
micro-organisms
Biotechnological
Processes
Products
Services
Food, enzymes, fuel,
antibiotics, hormones
Sewage treatment,
water purification
Yeast at Work
• Yeast is a tiny living thing, called a microbe.
• As you can see it is made of single cells.
• It is a type of plant called a fungus, (no
chlorophyll).
• It is used in baking and brewing.
Budding.
Yeast
Yeast is seen as a grey dust (bloom) on fruits.
A long time ago people crushed fruit and due to the
yeast on the surface of this fruit it fermented making
alcohol.
Yeast at Work
• Remember the equation for aerobic respiration?
• Glucose + Oxygen
water + carbon dioxide
+ energy
• All cells carry out this process, including yeast.
• However, biotechnology is about creating useful products and
carbon dioxide and water are not very profitable.
• If you take away oxygen though (anaerobic respiration)
– Glucose (sugar)
alcohol + carbon dioxide
+ energy
• So this is how alcohol is produced.
• This is called Fermentation
• When making alcohol the process is called
alcoholic fermentation.
• Yeast obtains energy by doing this.
Barley Grains
• The energy seeds need to grow is stored
inside them as starch.
• When they start to grow they convert this
starch to simple sugars using what enzyme?
– Amylase
• Beer making uses Barley for energy for the
yeast.
• However starch is too large for yeast to
digest so the grains have to be first left to
germinate to make sugar.
• This is called malting.
Grains allowed to germinate to
make sugar (seeds stopped
for using sugar themselves)
Dead sprouted grains (malt)
mashed and dissolved into
water = wort
Hops added for flavour and
wort boiled to kill bacteria
and wild yeast
Cooled and yeast added.
Fermentation stops when
alcohol kills yeast
Beer stored to allow it to mature
and filtered to remove sediment.
Spend
grains =
cattle food
Spent hops =
fertiliser
• Learning Intentions
– Understand biotechnology’s use of bacteria
• Success Criteria
• All can
– I can state 3 uses of yeast and describe yeast
– I can state the word equation for glucose fermentation
• Some Can
– I can describe and compare aerobic and anaerobic
respiration
– I can describe the manufacture of beer
– I can explain batch processing
– While discussing the need to malt barley I can give
ideal growing conditions for yeast.
Bacteria in food production
Converting Milk to Yogurt or
Cheese uses lactobacillus
• Learning Intentions
• Describe the uses of bacteria in biotechnology
• Success Criteria
• All can
– I can describe the process of cheese making
– I can describe the process of yoghurt making
– I can state that the souring of milk is a fermentation
process
– I can explain the souring of milk in terms of
fermentation of lactose
Milk
• Fresh milk straight from the cow usually has
a lot of bacteria.
• These bacteria feed on the milk (source of
food) and grow and multiply.
• It is for this reason milk is treated.
• The bacteria respire anaerobically (with out
oxygen) and feed on the sugar in milk (lactose)
turning it to lactic acid.
• This makes milk sour.
• The souring of the milk is a further example of
fermentation.
• Lactose
Lactic acid
• This is called Lactic acid fermentation
Cheese and Yoghurt
• To make cheese and yoghurt milk has to
curdle and lactic acid makes this happen.
•
1.
2.
3.
To make Yoghurt
Pasteurise milk (heated 73oC for 15s)
Let cool to 40 degrees celcius
Add yoghurt making bacteria (converts
sugar to lactic acid = curdling)
4. Notice the lowering pH as bacteria
convert lactose to lactic acid
5. Yoghurt is formed as lower pH
denatures proteins in milk (curdling)
over several hours.
6. Stored in fridge to slow down bacteria
growth
• Learning Intentions
• Describe the uses of bacteria in biotechnology
• Success Criteria
• All can
– I can describe the process of yoghurt and cheese
making
– I can state that the souring of milk is a fermentation
process
– I can explain the souring of milk in terms of
fermentation of lactose
Large Scale Microbe
Production
Learning Objectives
1. To understand how microbes are
cultured on a large scale.
2. To know how fungi can be used as a
meat substitute.
On a small scale
• You can grow
microbes on a
small scale in a
petri dish.
• They can get
plenty of food,
oxygen and
warmth to
grow.
On a small scale
• Waste that
bacteria
produce is not
a problem on a
small scale.
Simple Fermentation in the School Laboratory
In the school laboratory you may have used apparatus similar to
that shown below to investigate the effect of temperature or
glucose concentration on the rate of respiration in yeast.
The yeast culture is growing in conditions where the temperature is
controlled and glucose is provided - this is a basic fermenter.
On a large scale
• On an
industrial
scale, waste
can become
a problem.
Uses of Microbes
- Antibiotics
- Food
How do we go from
this…………….….to………….…..this…..?
A graph to show what is happening in the
fermenter
Problems with fermenters
- As numbers of microorganisms increase;
1. The food is used up.
2. The temperature increases as they respire.
3. Oxygen levels decrease as they respire.
4. As the carbon dioxide levels increase, the pH
changes.
5. As waste increases the microorganisms begin to
die.
Industrial Fermenters - Features
So what do we have to do to
overcome these problems?
- Oxygen is supplied for respiration.
- There is a stirrer to keep the microorganisms
spread out (not settling to the bottom) and the
temperature the same.
- There is a water cooled jacket around the
outside, to try and maintain the temperature, as
the microbes release heat.
- There are sensors to monitor the pH and
temperature.
Mycoprotein Production
• A new substance
was discovered
not long ago, a
food based on
fungi, and it is
called
mycoprotein.
• It is produced
using the fungus
Fusarium, which
grows and
reproduces very
rapidly based on a
cheap energy
supply (an
inexpensive sugar
syrup made from
waste
carbohydrates) in
a large fermenter.
Mycoprotein Production
• It does require areobic conditions to grow.
Its mass doubles every 5 hours or so, and this
biomass is harvested, purified and dried to
leave mycoprotein.
Mycoprotein Production
• On its own, it is
pale yellow in
colour and tastes
faintly of
mushrooms.
• But a range of
colours and
flavours can be
added to it to
enhance it.
Mycoprotein Production
• Mycoprotein
serves as a
high-protein,
low-fat meat
substitute.
This means it
is good for
dieters and
vegetarians.