Technologies K–10 · Years 3–4
Keeping cut apple fresh for a lunchbox
Design and Production (NSW Science and Technology K–6, 2017); Design and Technologies: Knowledge and understanding, Technologies context: Food specialisations (ACARA v9)
The idea
Cut apple turns brown when an enzyme in the fruit meets oxygen in the air, and preparation methods that cover the surface or make it acidic slow the browning.
Safety card
Hazards
- Knife cuts
- Food allergy
- Eating fruit that has been handled by many people
Controls
- Only an adult uses the knife
- Check allergy plans
- Test slices are not eaten
Note
No heat. Follow the NSW Department of Education anaphylaxis procedures; record on Primary School RiskAssess (riskassess.com.au).
What you need
- 2 apples of the same variety
- Knife and cutting board (adult use)
- 4 plates labelled: nothing, water, lemon juice, wrapped
- Lemon juice (1 lemon squeezed into a small bowl) and a bowl of tap water
- Cling wrap
- Colour score chart from 0 (no browning) to 4 (fully brown); timer; camera or tablet
How to do it
- An adult cuts each apple into 8 slices of the same thickness.
- Leave 2 slices untreated, dip 2 in water for 30 seconds, dip 2 in lemon juice for 30 seconds and wrap 2 tightly in cling wrap.
- Photograph all plates at the start.
- Score the cut surfaces at 15, 30 and 60 minutes and photograph each time.
- Repeat with the second apple.
- Choose a method for a lunchbox and give the test result as the reason.
What you should see
Untreated slices brown first. Lemon juice slices stay pale longest, because the acid and vitamin C slow the enzyme; wrapped slices brown less where the film touches the surface, because less oxygen reaches it; water gives a short delay. How fast browning shows depends on the apple variety, so the test compares methods on the same apple rather than predicting minutes. The learner knows it worked when the ranking from untreated (most brown) to lemon juice (least brown) repeats on the second apple.
What changes
- What you change
- the treatment of the cut surface
- What you measure
- the browning score (0 to 4) at 15, 30 and 60 minutes
- What you keep the same
- the same apple variety
- slices of the same thickness
- the same room temperature
- the same scoring chart
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- Brown apple is rotten (browning is a surface reaction; the fruit is not spoiled).
- Browning is caused by the knife (it is caused by the fruit's enzyme reacting with oxygen).
- Water stops browning (it only slows it for a short time).
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Science and Technology K–6 Syllabus (2017), NESA. The syllabus taught in 2026; the 2024 syllabus replaces it from 2027. Code read from the official syllabus document (DOCX) on 2026-09-22.ST2-2DP-T
- Science and Technology K–6 Syllabus (2024), NESA. Implementation from 2027, so this code describes the future syllabus. Code read from the outcomes page on 2026-09-22.ST2-DDT-01
- Australian Curriculum v9AC9TDE4K04
Sources
The pages the author read to write this activity.