Transcript food productionx

Food production and preservation
Key Words to define:
Autotroph
-
Heterotroph
-
Selective breeding
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Artificial selection
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Fertlisers
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Mycoprotein
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Food spoilage
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Pasteurisation
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Irradiation
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Sterilisation
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Ancient Biotechnology
~50,000 years ago - at least
two different species of
“people” (H.sapiens,
H. neanderthalensis) began to pass on
cultural traditions. People
could “imagine”, share ideas,
plan ahead, honor their dead.
They began to see the world
as something that could be
manipulated.
10,000 years ago - the traditions of agriculture and
animal husbandry began to develop.
Wheat, rye, barley, goats, sheep
Early Agriculture
Even relatively primitive
peoples understood that
selective breeding had
positive outcomes.
-larger grain seeds  flour
-selective breeding of goats
and eventually cattle to
increase milk production
and meat content.
Agrarian societies unknowingly participated in genetic
manipulation to make useful products for humans.
SELECTIVE BREEDING IS BIOTECHNOLOGY
Modern Example of Selective Breeding
Selective Breeding of Kale
(Brassica oleracea)
Cabbage
Brussels Sprouts
Cauliflower
Kohlrabi
Kale
This is modern Kale. Its ancestor provided
the stock for the selective breeding of the
other subspecies.
The large terminal buds of the plant were
selected to produce cabbage.
Large lateral buds were selected to produce
Brussels Sprouts
Principles of artificial selection:
• Breeders choose features they wish to
improve.
• Individuals with those features are bred
together.
• Offspring with improvement are selected to
breed in next generation.
• Continues over next 10+ years
Cauliflower was produced by selecting for
large, white flower stalks.
For broccoli, large stems and flower stalks
were both selected.
Kohlrabi was
produced by
selecting for short,
fat stems
And this is modern Kale.
Remember, all
of the vegetables
that you have seen
are the SAME
SPECIES - EACH
PRODUCED BY
SELECTIVE BREEDING; TAKING
ADVANTAGE OF WILD TYPE GENES
AND NATURAL MUTATIONS.
Coming to a supermarket near you soon…
Other examples - crops:
• Yields of grain (wheat, rice), roots (carrots)
and tubers (potatoes)
• Pest resistance – insects, fungi, bacteria,
viruses
• Better quality – appearance, taste
Other examples - livestock:
•
•
•
•
Yield of meat, milk, eggs
Fast growing breeds
Disease resistance ( eg blue tongue disease)
Quality – lean, low fat meat
All the
same
species
– Ovis
aries
Improving the environment
improves food production…
Fertlisers – NPK and Mg:
• Nitrates – making amino acids
• Phosphates – DNA, RNA, ATP, phospholipids
• Potassium – enzyme co-factor; guard cell
opening
• Magnesium – making chlorophyll
Organic vs
inorganic?
• Inorganic:
• Higher yield, cheaper, trace contaminants
• Organic;
• Lower yields, more expensive, no trace
contaminants
Pesticides
• Herbicides – kill weeds that compete
• Fungicides – against mildew, blight and rust
• Insecticides – applied when levels threaten
economic loss.
• Organic – use none of the above.
• Crop rotation and natural predators
(biological control)
Organic farming
Use of Microorganisms
Bacteria
cheese, yogurt, antibiotics
Fungi
cheeses
Yeast ( single celled fungus)
bread, beer
C6H12O6  CO2 + C2H5OH
Louis Pasteur (1860’s)
clearly demonstrated that
microbes are responsible
for fermentation.
Produce traditional products in
clever, new ways
-increase crop
productivity, meat
production, and
milk production
“The miracle of Genetic Engineering”
Mycoprotein
Uses a fungus Fusarium ( strain PTA-2684)
First discovered in a field in Buckingham in 1967
Now grown on an industrial scale to make ‘Quorn’
Advantages
• Microbes grow quickly – high yields in
short time.
• Uses less land to grow; can be set up
anywhere
• Uses waste material ( eg whey) as a
substrate
• No ethical issues with breeding / vegans
• Low fat or no-fat foods
Disadvantages
• Contamination of culture vessels
• Consumer resistance / suspicion
• Need to have a substrate, produced by
something else.
• Needs purifying before use
The future - modifying genetics to produce
organisms with new “recombinant” traits.
-plants with
resistance to
disease and
parasites.
-replacing a
defective gene
in a crop plant or
animal
‘Agrobacterium’
Food Spoilage
Aspergillus
fungus – the
aflatoxins it
produces are
carcinogenic
Preservation – removes one of
the conditions that microbe needs
to survive…
Salting / Sugaring
• Lowers wp. Removes water from microbes
by osmosis
• Eg salted cod, jams
Pickling
• Ethanoic acid (vinegar) – lowers pH to <4
• Microbe enzymes denature.
• Eg pickled cabbage, onions
Heat Treatment -1
• Pasteurisation – brief
flash heating to 72C
for 15 seconds.
• Kills pathogens but
not Lactobacillus, so
flavour is preserved.
Heat Treatment -2
• UHT – brief flash
heating to 135C for 15
seconds.
• Kills all bacteria, but
flavour is
compromised.
Freezing
• Water is frozen, so not available to
microbes.
• Enzymes are inactivated.
• Eg meat
Irradiation
• X-rays or Gamma rays
kill microbes by
denaturing proteins and
DNA.
• Eg fruit, prawns
Homework:
• 1. Describe, using examples from
agriculture, the principles of selective
breeding.
• 2. Explain the term ‘food spoilage’ and
describe how food may be prevented from
going ‘off’.