Food production and preservation

Key Words to define:

Autotroph -

Heterotroph -

Selective breeding -

Artificial selection -

Fertlisers -

Mycoprotein -

Food spoilage -

Pasteurisation -

Irradiation -

Sterilisation -

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 worldas something that could bemanipulated.

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

Selective Breeding of Kale (Brassica oleracea)

CabbageBrussels SproutsCauliflowerKohlrabiKale

Modern Example of Selective Breeding

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, allof the vegetables that you have seen are the SAME SPECIES - EACHPRODUCED BYSELECTIVE 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 MicroorganismsBacteria

cheese, yogurt, antibioticsFungi

cheesesYeast ( single celled fungus)

bread, beerC6H12O6 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”

MycoproteinUses 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 produceorganisms 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’.