Homemade Strawberry Jam
Homemade strawberry jam from three ingredients: strawberries, sugar and lemon. No preservatives and no added pectin — the set comes from cooking it down, and you check it with the cold plate test.
Makes about two jars, and in season it costs half what the store-bought jar does.
The lemon is not decoration: it brings the pectin and the acidity that keep the jam.
Ingredients
- 1 kg ripe strawberries, hulled
- 600 g sugar
- Juice of 1 lemon
Method
- 1
Halve the strawberries and toss them in a bowl with the sugar and the lemon juice. Let them macerate for 30 minutes (or overnight in the refrigerator): they release their juice and cook down better afterwards.
- 2
Move everything to a wide pot — wider is better than taller, it evaporates faster — and bring it to a boil over high heat, skimming off the foam that rises.
- 3
Lower to medium heat and cook for 35-45 minutes, stirring now and then so it does not catch. Crush the strawberries with the spoon as much or as little as you like your jam.
- 4
Cold plate test: put a teaspoonful on a plate that has been in the freezer, wait a few seconds and push it with your finger. If it wrinkles instead of running, it is ready.
- 5
Jar it hot in sterilized jars that are still warm — a cold jar can crack when boiling jam goes in. Seal, and stand them upside down for 10 minutes to draw a simple vacuum.
- 6
Sealed and kept somewhere cool and dark they last about a year. Once a jar is opened it goes in the refrigerator and should be eaten within four weeks or so.
Frequently asked questions
Can the jam be made faster?
Yes, with sugar that already has pectin in it. The cooking time drops from 35-45 minutes to about 4 minutes from the moment it boils, and it sets reliably without depending on the cold plate test.
Watch out for the part that looks obvious and is the other way round: with this kind of sugar, cooking it longer does not make it firmer, it makes it runnier. Pectin breaks down under prolonged heat. Four minutes and into the jars.
Ratio: 500 g of 2:1 jam sugar per kilo of fruit, instead of the 600 g of ordinary sugar. The lemon stays the same in both versions: it is the acid that lets the pectin set at all.
What it is called depends on where you are. In the UK and Ireland it is jam sugar (or preserving sugar with added pectin), on the shelf in any supermarket. In Australia and New Zealand, jam setting sugar. In the United States it is far less common as a sugar — there you usually buy powdered pectin separately (Sure-Jell, Certo, MCP) and follow the ratios on the box, which are not the same. If you cannot find any of it, the recipe above works perfectly well — it just spends longer in the pot.
And one detail that matters for this recipe: 2:1 and 3:1 jam sugars usually contain sorbic acid, which is a preservative. That is why the version above, with plain sugar, is the one that can be called preservative-free.
More Recipes with Strawberries
Peak season depends on where you are — late spring to early summer in the northern hemisphere, spring in the southern one — but you will find them in the shops most of the year. They are at their best in cakes, shakes and homemade jam. Recetop tip: buy them in season, wash and dry them well, hull them and freeze them in zip bags; that way you always have a handful ready for smoothies.
