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 Additives1. Colours: More attractive2. Flavourings: Enhance taste3. Artificial Sweeteners: Reduce amount of sugar4. 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.