Apple browning

This practical not only explores oxidisation, but leaves learners with a snack. 

This experiment should take 60 minutes. 

Equipment

• Eye protection
• Yoghurt pots
• Aluminium foil – students may think light causes browning
• Kettle
• Apples
• Salt
• Sugar
• Vinegar
• Lemon juice
• Bicarbonate of soda
• Access to water

Health, safety and technical notes 

Read our standard health and safety guidance here.

Wear eye protection.

This is an open-ended problem-solving activity, so the guidance given here is necessarily incomplete

Consider the safety aspects of eating in the lab

Possible approaches

Questions to ask students who need help are:

1. Do they need to use a whole apple each time, or can they use tiny slices?
2. Would it be best to cut the apple up first, or to get everything else ready first? Is cold water better than warm water?
3. Apart from water, what else might you safely try? (e.g. salty water, sugary water, vinegar, lemonade, bicarbonate of soda, anything else?)
4. How can you make your tests fair?

Each group could make a presentation to the class of their findings. At the end of each talk, encourage ‘members of the audience’ to ask the speakers any questions, as one might do at any scientific meeting.

As envisaged, the experiment is of low hazard and eye protection will not be needed. If any hazardous substances are chosen, their use should be risk assessed. 

Possible extension

Why is lemon or orange juice squeezed over a fruit salad containing apples, pears or bananas? Find out about the preservatives in your favourite food.