Researching Chemistry - Antioxidants• Researching Chemistry consists of two assessment

activities (assessed by your teacher):

This will help you greatly when it comes to writing your assignment later (assessed by SQA).

ASSESSMENT ACTIVITY 1- Literature research, including:

• More focused research surrounding the aim of your investigation. (2 sources required)

• Finding out about the Underlying Chemistry of antioxidants - you must keep a record of all your notes and of all sources you use. (2 sources required)

• A plan of the practical investigation (including a clear aim, hypothesis, variables, method and risk assessment)

• A record of observations/measurements including labels and units (i.e. ALL raw data).

• The candidate should be observed to follow procedures safely.

• A full investigation write-up, including presenting findings in an appropriate format.

Researching Chemistry - Antioxidants

The raw data from Researching Chemistry will be used as data source 1 in your assignment.

ASSESSMENT ACTIVITY 2- Practical research, including:

Introduction to antioxidants

Oxidative damage• Oxidation reactions can produce free radicals.

• A free radical is a highly reactive species containing an unpaired electron.

• Free radicals can damage food (also plastics and living organisms) by removal of an electron.

• Antioxidant molecules ‘mop up’ free radicals to protect the foodstuff.

Damaging free radical

Electrontransferred

Antioxidant/free radical scavenger

Antioxidant converted to a stable free radical

Neutralised free radical

Radical now in a stable pair

How antioxidants work

How does an antioxidant cancel out a free radical?

The antioxidant molecule is a free radical scavenger – it donates an electron to the potentially damaging free radical.

A stable electron pair is formed, stabilising the free radical.

The antioxidant itself becomes oxidised (loses an electron).

https://www.youtube.com/watch?v=QM3lMKoT6U0

Antioxidants – short video clips

Understanding antioxidants

https://www.youtube.com/watch?v=lG3OOXIXvxw How antioxidants work

https://www.youtube.com/watch?v=T_Xo5AaTH8U Free radical analogy

http://www.bbc.co.uk/guides/zwpyvcw#zs9wjxs BBC antioxidants

Antioxidants in action

Oxidation occurs when the apple is left exposed to air

The apple is protected when dipped in orange juice containing the antioxidant vitamin C

Antioxidants

Oxidation reactions happen when chemicals in the food are exposed to oxygen in the air. In natural conditions, animal and plant tissues contain their own antioxidants but in foods, these natural systems break down and oxidation is bound to follow.

Oxidation of food is a destructive process, causing loss of nutritional value and changes in chemical composition. Oxidation of fats and oils leads to rancidity and, in fruits such as apples, it can result in the formation of compounds which discolour the fruit.

Antioxidants are added to food to slow the rate of oxidation and, if used properly, they can extend the shelf life of the food in which they have been used.

http://www.understandingfoodadditives.org

Examples of antioxidants

OCH3

NH NH CH3

O

O

OH

CH3 CH3

CH3

CH3

CH3 CH3H H

CH3

CH3

CH3CH3

CH3CH3

CH3

CH3CH3

CH3CH3

CH3

Vitamin C

Melatonin

Vitamin E

-carotene

Vitamin C (ascorbic acid)

• The antioxidant vitamin C can act as a reducing agent (electron donor), preventing oxidation (electron loss) from the foodstuff.

C6H8O6 C6H6O6 + 2H+ + 2e-

Ascorbic acid

Dehydroascorbic acid

This is a hormone which helps to regulate sleep in our bodies. This compound can be termed as a terminal or suicidal antioxidant as once it has removed the free radicals it has to be replaced.

OCH3

NH NH CH3

O

Melatonin

This is a form of vitamin E and can be found in vegetable oil, nuts and seeds. It has been suggested that it is good for the skin.

O

OH

CH3 CH3

CH3

CH3

CH3 CH3H H

CH3

CH3

α-tocopherol

Ascorbic acid is also known as Vitamin C and is commonly found in fruits and vegetables. It is one of the essential vitamins and the human body is unable to synthesize it. It can be easily oxidised and acts as a hydroxyl or superoxide anion free radical scavenger.

OO

OHOH

OHH

OH

Ascorbic Acid (Vitamin C)

CH3CH3

CH3CH3

CH3

CH3CH3

CH3CH3

CH3

β-carotene

This is a precursor to vitamin A. It is a highly red-orange pigment found in plants and fruits. In particular it gives carrots their orange colour. It helps human cells to absorb vitamin A.

Antioxidant E-number

Typical foods

Ascorbic acid (vitamin C)

E300

Beers, cut fruits, jams, dried potato. Helps to prevent cut and pulped foods from going brown by preventing oxidation reactions that cause the discolouration. Can be added to foods, such as potato, to replace vitamin C lost in processing.

Tocopherols(Vitamin E)

E306 Oils, meat pies. Obtained from soya beans and maize. Reduces oxidation of fatty acids and some vitamins.

Butylated hydroxyanisole (BHA)

E320 Oils, margarine, cheese, crisps. Helps to prevent the reactions that break down fats and cause the food to go rancid .

Citric acid E330

Jam, tinned fruit, biscuits, alcoholic drinks, cheese, dried soup. Naturally-occuring in citrus fruits like lemons. Helps to increase the anti-oxidant effects of other substances. Helps to reduce the reactions that can discolour fruits. May also be used to regulate pH in jams and jellies.

http://www.understandingfoodadditives.org

Antioxidants as food additives

Impact of antioxidants on health

The imbalance between free radicals and antioxidants can lead to disease and ill health. The 4 main non-enzymatic antioxidants metalonin, α-tocopherol (Vitamin E), ascorbic acid (Vitamin C) and β-carotene (precursor for Vitamin A) can be found in a range of foods in our diet. However medical opinions are divided as regards the impact these antioxidants have our on general health.

Free radicals in living cellsFree radicals are present in all living cell and are a part of the cell processes. However excessive free radicals in our cells can attack the cell membranes (the outer coat of the cell). This attack causes cell and tissue damage.Radicals can also break strands of DNA (the genetic material in the cell). Some of the chemicals known to cause cancer, do so by forming free radicals.

Antioxidants and health benefits

There may be health benefits from the use of antioxidants. Oxidation reactions in the body could be linked to the build-up of fatty deposits that cause blockages in arteries that can cause heart attacks. Antioxidants may be important in preventing this and there could also be a link with the prevention of certain cancers, arthritis and other conditions. The picture is not yet clear and a great deal of research needs to be undertaken.

http://www.understandingfoodadditives.org

Do antioxidants help us live longer?

Studies involving 230,000 men and women across the UK have shown that there is no convincing proof that antioxidants have any effect on how long people can live. However 40% of women and 30% of men are reportedly taking these supplements and spending over £333 million on them per year.

Researching Chemistry – your first task

Your first task is to research the Underlying Chemistry of antioxidants. - you must keep a record of all your notes and of all sources you use. (2 sources required)

You must use appropriate sources for Higher Chemistry level. Can you think of any?

Higher Chemistry textbooks

Scholar website

Education Scotland website(google: Education scotland Chemistry)

Google ‘SSERC antioxidants’

You must provide ISBN numbers for books andfull urls for websites

Google ‘BBC antioxidants’ (for more general knowledge)

Researching Chemistry – your first task

Your first task is to research the Underlying Chemistry of antioxidants. - you must keep a record of all your notes and of all sources you use. (2 sources required)

What do you think might be appropriate content for the underlying Chemistry of antioxidants?

• Antioxidants are free radical scavengers

• What is a free radical and how are they formed? (what causes free radicals?)

• What damage can free radicals do? – to humans and food.

• Explanation of free radical chain reactions

• How antioxidants can stop them• Examples of antioxidants

Researching Chemistry – your first task

Your first task is to research the Underlying Chemistry of antioxidants. - you must keep a record of all your notes and of all sources you use. (2 sources required)

What do you think might be appropriate content for the underlying Chemistry of antioxidants?

• Do not copy text from textbooks or websites– that is called plagiarism and I will be looking out for it.

• Make notes explaining concepts in your own words please.

Researching Chemistry - Antioxidants• Researching Chemistry consists of two assessment

activities (assessed by your teacher):

This will help you greatly when it comes to writing your assignment later (assessed by SQA).

ASSESSMENT ACTIVITY 1- Literature research, including:

• More focused research surrounding the aim of your investigation. (2 sources required)

• Finding out about the Underlying Chemistry of antioxidants - you must keep a record of all your notes and of all sources you use. (2 sources required)

Researching Chemistry – your first task

Your first task is to research the Underlying Chemistry of antioxidants. - you must keep a record of all your notes and of all sources you use. (a minimum of 2 sources is required)

Appropriate content for the underlying Chemistry of antioxidants:

• Antioxidants are free radical scavengers• What is a free radical and how are they formed? (what causes free radicals?)

• What damage can free radicals do? – to humans and food.

• Explanation of free radical chain reactions (examples in food)

• How antioxidants can stop them• Examples of antioxidants and their structures

Researching Chemistry – your second task

Your second task is to undertake more focused research surrounding the aim of your investigation – again, you must keep a record of all your notes and of all sources you use (a minimum of 2 sources for this section is required)

I will be coming round and assessing your work by reading your research notes and asking you questions –

i.e. How much of what you have written do you understand and can explain to me?

Researching Chemistry-practical investigation/focused

research Your practical investigation will be one the following:

1.Which fruit juice contains the most antioxidants?

Or

2. Which tea contains the most antioxidants?

The class will be split into 4 groups:2 groups researching teas and 2 groups researching fruit juices.

Researching Chemistry - possible focus questions

A1. Explain why the human body requires antioxidants.

A2. Many foods and drinks which contain antioxidants are known as ‘superfoods’. What requirements must be met for a food to be labelled as a ‘superfood’?

A3. What evidence is there to suggest that eating ‘superfoods’ is good for human health?

A4. Many people make fruit smoothies to get their daily allowance of vitamins from fruits. It is thought that smoothies can be harmful to health. What evidence is there to support this?

1. Which fruit juice contains the most antioxidants?

Researching Chemistry - possible focus questions

B1. Is there any evidence to suggest that drinking tea leads to better health?

B2. Why do different types of tea contain different concentrations of antioxidants?

B6. Green tea is recognised to be very beneficial to health. Describe the health benefits of drinking green tea.

2. Which tea contains the most antioxidants?

Researching Chemistry – a clear statement describing your

research topicOnce you have completed all your research for the underlying Chemistry of antioxidants and your more focused research surrounding the aim of your investigation, you now need to write a clear statement describing your research topic. i.e. a concise summary of both sets of literature research.

This should only be one or two paragraphs and can include diagrams.

Researching Chemistry – a clear statement describing your research topic

One or two paragraphs – must be clear and concise! What you could include:-What is a free radical? How are they formed?-What damage can they do? (to humans/food)-What are antioxidants/how do they work?-Examples of foods or teas high in antioxidants-Possibly a structure of an antioxidant-Possible health benefits of antioxidants (something about your focus question)-What is the aim of your investigation?-Name of the experiment you will be carrying out (Briggs-Rauscher experiment)

Researching Chemistry-practical investigation

Your practical investigation will be one the following:

1.Which fruit juice contains the most antioxidants?

Or

2. Which tea contains the most antioxidants?

Our class will be split into 4 groups:2 groups researching teas and 2 groups researching fruit juices.

• A plan of the practical investigation (including a clear aim, hypothesis, variables, method and risk assessment)

• A record of observations/measurements including labels and units (i.e. ALL raw data).

• The candidate should be observed to follow procedures safely.

• A full investigation write-up, including presenting findings in an appropriate format.

Researching Chemistry - Antioxidants

The raw data from Researching Chemistry will be used as data source 1 in your assignment.

ASSESSMENT ACTIVITY 2- Practical research, including:

• AIM• HYPOTHESIS• VARIABLES (Independent, dependent and variables to remain

constant)• PLAN for your METHOD – you can either photocopy the method

from SSERC or write in the full URL.• RISK ASSESSMENT – you need the quantities and the composition of

the solutions you will be using. you need to check hazard symbols and come up with appropriate safety precautions.

• RESULTS - A record of observations/measurements including labels and SI units (i.e. ALL raw data).

• You should be observed by me to follow procedures safely.• Once completed your experiments, you should write a full

investigation write-up, including presenting findings in an appropriate format (same as a task 1).

Researching Chemistry - Antioxidants

https://www.youtube.com/watch?v=yNsCU-_V0oM Briggs-Rauscher Reaction 2

https://www.youtube.com/watch?v=IggngxY3riU Briggs-Rauscher Reaction 1

Briggs-Rauscher Reactions

Briggs-Rauscher Reaction

Watch the demo of the reaction you are going to carry out – you may takes notes if you want, although the detailed instructions are in the SSERC Antioxidants Student’s Guide.

Think about variables!

Risk Assessment

For your risk assessment, you must:1.State the name of the chemical, 2.The quantity you are going to use, 3.The safety precaution(s) you are going to take.

Risk Assessment

Solution A: 50 cm3 0.2 M potassium iodate and 0.07 M sulphuric acid.

Solution B: 50 cm3 0.15 M malonic acid and 0.2 M manganese sulphate.

Solution C: 50 cm3 4 M hydrogen peroxide.

Teas or fruit juices.

Skin irritant

Skin irritant Corrosive

Hazardous to aquatic environment

HealthHazard

Check for possiblefood allergies

Safety precautions

Harmful irritant

Corrosive

Wear goggles.Clean up any spills.Wash any spills off skinimmediately with plenty water.

Wear goggles and gloves.Clean up any spills.Wash any spills off skinimmediately with plenty water.

Safety precautions

Health hazard

Hazardous to the aquatic environment

Do not put down the sink.

Put into a waste bottle for thetechnician to dispose of.

Do not inhale or ingest.

• AIM• HYPOTHESIS• VARIABLES (Independent, dependent and variables to remain

constant)• PLAN for your METHOD – you can either photocopy the method

from SSERC or write in the full URL.• RISK ASSESSMENT – you need the quantities and the composition of

the solutions you will be using. you need to check hazard symbols and come up with appropriate safety precautions.

• RESULTS - A record of observations/measurements including labels and SI units (i.e. ALL raw data).

• You should be observed by me to follow procedures safely.• Once completed your experiments, you should write a full

investigation write-up, including presenting findings in an appropriate format (same as a task 1).

Researching Chemistry - PLAN