You have probably noticed that apples taste sweeter after sitting on the counter for a few days. But does every type of apple gain sugar at the same rate once it leaves the refrigerator?
You take three varieties out of cold storage at the same time:
- Red Delicious
- Golden Delicious
- Granny Smith
Twice a week, juice three apples of each type and place three drops on a refractometer. This tool measures sugar in degrees Brix. Track the readings over several weeks until all the apples are used.
Compare the sugar curves to discover which variety changes the most after leaving cold storage.
Hypothesis
The hypothesis was that red delicious apples would have a greater amount of sugar content change than granny smith and golden delicious apples over time when removed from cold storage.
When apples leave cold storage, they keep ripening — and their sugar levels keep climbing. A refractometer measures this increase in degrees Brix, giving a precise look at how sweetness builds over time. Not every variety follows the same curve, though. Red Delicious, Golden Delicious, and Granny Smith each gain sugar at different rates, so the variety you pull from the refrigerator determines how quickly that post-storage sweetness arrives.
Place three drops of freshly juiced apple on a refractometer and it measures dissolved sugar in degrees Brix — a standard unit for sugar concentration. As apples sit on the counter after leaving cold storage, their sugar levels shift. By recording Brix readings for each variety twice a week over several weeks, you build a sugar curve for granny smith, golden delicious, and red delicious apples. That means you can compare not just how sweet each variety is, but how fast it changes once it comes out of the refrigerator.
Method & Materials
You will label cups for each apple type, slice the apples, run them through a juicer, collect the juice, put three drops of each apples juice on a refractometer, and record the sugar content.
You will need a refractometer, ripe granny smith apples, ripe golden delicious apples, ripe red delicious apples, a fruit juicer, pipettes, three ounce cups, a marker, a sharp knife, and a box of Kleenex.
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The results showed that all of the apples started around 12* brix, but the golden delicious apples increased the most (to 12.93* brix). The red delicious apples decreased at first then increased (to 11.9067* brix). The granny smith apples decreased, then increased, then decreased (to 11.0267* brix).
Why do this project?
This science project is interesting because it shows how different types of apples can change in sugar content over time when taken out of cold storage.
Also Consider
Experiment variations to consider include testing different types of apples, testing different temperatures of cold storage, and testing different amounts of time out of cold storage.
Full project details
Additional information and source material for this project are available below.
