Food additives 2higher

What Does the Fungus Know That You Don't?

Does the fungus love McDonalds?

Chips and burgers left in the open air – see the fungus and bacteria grow!

Friendly staff but not very friendly food

Lesson outcomes

• E - State that oil and water do not mix• E - State that emulsifiers help oil and water to mix and

not separate• C - Describe emulsifiers as molecules that have a

water–loving part (hydrophilic) and an oil– or fat–loving (hydrophobic) part

• C - State examples of foods that contain emulsifiers e.g. mayonnaise

• A - Describe how an emulsifier helps to keep oil and water from separating using the words :

• hydrophilic• hydrophobic

Detergent

• Why is it hard to wash oily plates in hot water without a washing up liquid (detergent)?

Oil and water – don’t mix

But if you add washing up liquid (detergent), what happens?

A detergent in washing up liquid provides “hooks” between oil and water.

This is an example of an emulsion

A detergent is an emulsifier

A Detergent is an emulsifier

• Detergent is made up of molecules that act in a very special way.

• A detergent molecule is long and thin. One end of the detergent molecule is good at attaching to water and the other end is good at attaching to grease and oil.

• You've seen that oil and water, by themselves, don't mix well. But if detergent is added, one end of the detergent molecules gets attached to the oil and the other end gets attached to water.

Water loving part

Oil loving part

Long molecule of a detergent

Examples of emulsions

• Milk• Mayonnaise• Emulsion paint

We all love smooth foods and they get that way through the use of emulsifiersThe classic emulsion is milk, a complex mixture of fat droplets suspended in an aqueous solution.

Experiment – making mayonnaiseSafety!You must not eat anything in the lab.You will need:test tube and corkoilwateregg yolk (you will use eggs with the lion stamp onthem as these are salmonella free)dropping pipetteMethodPour oil into a test tube until it is a third full.Add the same volume of water. 1. What happens?Cork the test tube and shake. Leave for a minute.2. What happens now?Add five drops of egg yolk to the test tube. Cork and shake again.3. What happens this time?

Experiment – making mayonnaise

Conclusion

1. Describe what you found out during the experiment.

2. Egg yolk helps hold the oil and water together. What is it called? Circle the correct answer below.

immobiliser emulsifierundulation

Plenary

• Describe how an emulsifier helps to keep oil and water from separating using the words :

• hydrophilic

• hydrophobic

Cut the Mustard

• How you could make a salad dressing without using raw egg yolk as the emulsifier?

Powdered mustard acts as an emulsifier in the preparation of mayonnaise and salad dressings.

homework

• After eating your mayonnaise, find out the cure for salmonella (it may be helpful)!