Agriculture and Food 7–12 · Years 11–12
Jam and jelly setting point: sugar, pectin, acid and temperature
Food Manufacture: preservation
School laboratory, not for home
In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.
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The idea
Jam sets when enough water has boiled off for sugar, pectin and acid to form a gel, which happens at 8 °F (4.4 °C) above the local boiling point of water, so the setting temperature falls with altitude.
Safety card
Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.
Hazards
- boiling sugar mixture above 100 °C sticks to skin and causes deep burns
- splattering during rapid boiling
- hot glass jars
Controls
- long sleeves, oven mitts and a deep pan
- long-handled spoon; learners stand back while it boils
- teacher present throughout; jars cooled away from bench edges
Note
Food handling follows the FSANZ food safety standards (Standard 3.2.2) as explained on the FSANZ food temperature and thermometers page; check class allergy and anaphylaxis records before any food is prepared; the Food Technology Years 7–10 Syllabus reminds teachers that food allergies can cause anaphylaxis. Heat: complete a RiskAssess or school risk assessment for boiling sugar.
What you need
- fruit, sugar and lemon juice in the quantities of a tested recipe for jam without added pectin (for example an NCHFP recipe)
- heavy-based wide saucepan, long-handled wooden spoon
- sugar (candy) thermometer that reaches at least 110 °C
- cold metal spoons and saucers chilled in the freezer
- clean, hot jars and lids for refrigerated classroom use
- long sleeves, oven mitts
How to do it
- Check the thermometer in boiling water and record the local boiling point; the setting target is that reading plus 4.4 °C.
- Prepare the fruit, add sugar and lemon juice as the recipe directs, stir until the sugar dissolves, then boil rapidly, stirring.
- Every 2 minutes read the temperature; when it nears the target, take the pan off the heat and do the freezer-plate test, which is the test NCHFP gives for jam (the spoon or sheet test is its test for jelly).
- Record the temperature at which each test first shows a set, and stop at the setting point.
- Pour into hot jars, cool, refrigerate and assess the set next day.
- Extension: make a second batch with half the sugar or without lemon juice and compare the set.
What you should see
The freezer-plate test first shows a set close to the target temperature, which is 104.4 °C (220 °F) at sea level. The National Center for Home Food Preservation table lowers it 2 °F for each 1000 feet of elevation, to 214 °F (101.1 °C) at 3000 feet (914 m). The reduced-sugar or no-acid batch sets softly or not at all, because a gel needs the right ratio of fruit, pectin, acid and sugar. The learner knows it worked when the thermometer check in boiling water was done first and the set tests agree with the temperature.
What changes
- What you change
- sugar or acid level (extension)
- What you measure
- temperature at which the set tests pass (°C); firmness of the set next day
- What you keep the same
- fruit type and quantity
- pan
- heat setting
- testing interval
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- Jam sets as soon as it boils.
- Sugar in jam is only there for sweetness.
- The setting temperature is the same everywhere.
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
Sources
The pages the author read to write this activity.
- nchfp.uga.edu/how/make-jam-jelly/jams-jellies-general-information/testing-jelly-without-added-pectin
- nchfp.uga.edu/how/make-jam-jelly/jams-jellies-general-information/jellied-product-ingredients
- www.nsw.gov.au/education-and-training/nesa/curriculum/tas/food-technology-stage-6-2013
- www.nsw.gov.au/sites/default/files/noindex/2025-03/food-technology-st6-syl.docx
- nchfp.uga.edu/how/make-jam-jelly/jams-jellies-general-information/making-jam-without-added-pectin