C3: Food Matters
Many Chemicals in Living Things are
Natural Polymers
• Carbohydrates:
– Carbon, Hydrogen,
Oxygen
– Cellulose, Starch, Sugar
• Proteins:
– Carbon, Hydrogen,
Oxygen, Nitrogen
– Amino Acids, Proteins
• There is continual cycling of elements through
consumption of living organisms and decay
Crop Harvesting
• Elements such as nitrogen, potassium and
phosphorus, are lost from the soil so that the land
becomes less fertile unless these elements are
replaced
Intensive Farming
• Try to produce as much food from their land as possible
(Maximise Yield)
– Synthetic Fertilizers: replace soil nutrients
– Pesticides/Fungicides: kill pests and disease-causing fungi
– Herbicides: kill weeds that compete with crops for nutrients, light,
and water
Organic Farming
• Take care to produce food without damaging
environment. Follow UK Standards.
– Manure: replace soil nutrients
– Natural Predators: control pests
– Crop Rotation: replace soil nutrients naturally +
reduce crop diseases
Food Additives
1.
2.
3.
4.
Colours: More attractive
Flavourings: Enhance taste
Artificial Sweeteners: Reduce amount of sugar
Emulsifiers and Stabilisers: Help mix ingredients
together that wouldn’t normally mix. EG: oil and
water
5. Preservatives: Keep food safer longer. Prevents
growth of microorganisms
6. Antioxidants: added to foods containing fats or oils
to prevent them deteriorating by reaction with
oxygen in the air
• Scientific Advisory Committees carries out risk
assessments to determine the safe levels of
chemicals in food
E Numbers
• Additives with an E number have passed a safety
test and been approved for use in the UK and the
rest of the EU
• Health concerns about the use of some additives
Natural Toxins
• Natural chemicals in plants may be toxic,
cause harm if not cooked properly, or may
give rise to allergies in some people
Alfatoxin
• A harmful chemical in food, produced by moulds
that contaminate crops during storage
Harmful Chemicals
• Traces of pesticides and
herbicides may remain in
the products we eat
• Harmful chemicals may
form during food processing
and cooking
• Foods rich in starch that’s
been cooked at high
temperatures contain
acrylamide. This is known
to cause cancer in animals
How to Reduce how many
Harmful chemicals you consume?
• Eat more organic foods
• Eat foods which haven’t been processed very
much. Ie: fresh fruit and vegetables.
Food Labels
• Give information about
ingredients, additives,
nutrients.
• Can be misleading. It might
say “fat free”, but how much
sugar is in it?
Food Standards Agency (FSA)
• Food Standards Agency is an independent
food safety watchdog set up by an Act of
Parliament to protect the public's health and
consumer interests in relation to food
Regulations and the Future
• Scientific research and applications are subject to
official regulations and laws (government)
• Technically feasible: what can be done
• Values: what should be done
• Sustainable development: aims to meet human
needs while preserving the environment so that
these needs can be met not only in the present, but
also for future generations
Precautionary Principle
• It is impossible for anything to be completely safe. A
positive change to the environment for one organism
(adding fertilizer) may be a negative one for another.
• Better Safe than Sorry
• To the people who believe a new technology is not safe, it
is up to them to prove that it is. Otherwise society /
individual will continue to believe that there is a danger.
• Examples:
– A new untested pesticide
Digestion of Protein
• Protein broken down into Amino Acids and
then transported by the blood around the
body.
Digestion of Starch
• Starch broken down into Glucose and then
transported by the blood around the body.
Protein
• Cells grow by building up amino acids from the
blood into new proteins
• These consist mainly of protein:
– haemoglobin in blood
– tendons
– muscle
– skin
– hair
Excreting Protein
• Excess amino
acids are broken
down in the liver
to form urea,
which is excreted
by the kidneys in
urine
Blood Sugar Levels
• High levels of sugar
(common in some
processed foods) are
quickly absorbed into
the blood stream,
causing a rapid rise
in the blood sugar
level
• The Hormone Insulin
controls Blood Sugar
Levels
• Type 1
– Starts in childhood
– Pancreas stops producing
enough insulin
– Controlled by insulin
injections
• Type 2
– Usually starts in adulthood
– Risk factors: obesity, poor
diet
– Body no longer responds
to its own insulin or does
not make enough insulin
– controlled by diet and
exercise
Benefits and Risks
• Can suggest benefits to a known risk and offer reasons
for people’s willingness/reluctance to accept the risk of a
given activity
• Convenience foods are easy and quick for people to use.
Eg: 5 minute microwave meals. Although they may have
undergone lots of processing.