Homemade Easy Plum Jam Recipe (2024)

FAQs

What is the secret to making jam? ›

The Magic of Macerating

One of my favorite tricks for jam-making is macerating the fruit first. Macerating is the process of coating the fruit in sugar and letting it rest for a few hours or overnight, which pulls some of the juice out of the fruit and creates a syrup with the sugar.

Over-ripe or damaged fruit is not ideal - the jam will not set well and is likely to deteriorate rapidly. The amount of sugar you need to make jam depends on the amount of pectin in your chosen fruit, but generally the fruit-to-sugar ratio for traditional jams is 1:1 (ie. 450g/1lb sugar to 450g/1lb fruit).

European plums, aka prune plums, are mainly grown to be turned into dried plums. Their thick skins, high sugar content, and dense flesh make them ideal for drying, and best for baking and jam-making.

Once the jam reaches a slow, thick boil, add lemon juice and continue to cook, stirring constantly until the jam returns to its earlier consistency, about another 5 minutes.

I prefer to make jam using normal granulated sugar or caster sugar. However, you can also use sugar with pectin added (also called “jam sugar“), and I find this sugar is most useful when you are making jam with fruit which contain low amounts of natural pectin.

Boil hard for 5-10 mins until the jam has reached 105C on a preserving or digital thermometer, then turn off the heat. If you don't have a thermometer, spoon a little jam onto one of the cold saucers. Leave for 30 secs, then push with your finger; if the jam wrinkles and doesn't flood to fill the gap, it is ready.

Making jam without pectin is easy, you just have to cook it longer. This recipe produces a very thick, rich tasting jam, but if you like your jam a bit looser, cook it 5 minutes less than the suggested cooking time.

When the pectin becomes grainy from being stirred into a higher-sweetener mixture, you can't get rid of the graininess by more cooking. The fix is to add enough more mashed fruit or unsweetened juice to bring the sugar or honey level down to within the original recipe's sweetener range.

Since pectin is activated by sugar, it requires using a considerable amount of sugar to activate the pectin and set (i.e. thicken) your jam. If you try to cut back on the sugar, it won't set properly. There are low sugar pectins that I have played around with but personally I find the texture to be less than desirable.

The natural pectin in fruits and vegetables thickens jams. If there isn't enough pectin in the fruit itself and you don't add extra pectin, the result is runny jelly or jam. Additionally, if the fruit is overripe, its pectin levels are lower.

How do you know when plum jam is ready? ›

You can also let the spoonful of jam sit on the cold plate for 30 seconds and then push it with your spoon or finger. If it wrinkles up, you've reached your setting point. TIP: Use a white plate so you can see the jam clearly. A darker plate or patterned plate may give you the impression your jam is set when it is not.

If, after waiting, you find the jam is still too loose for your liking, empty the jars back into a wide pot and cook again. Wash and sterilize the jars and try again. While you can simply reduce the jam to your liking, you can also add commercial pectin or chia seeds to the reducing jam to guarantee thickening.

If your recipe called for lemon juice and you forgot to put it in, your mixture will not be acid enough for safe canning. You have to open the jars and put the mixture into a sauce pan. (If you made the jam or jelly recently and you carefully remove the lids without damaging them, you can re-use the same lids.)

You can use bottled lemon juice or fresh. However, I personally look to use other complementary juices to certain fruit jams. Rather than rely on lemon juice I would for example use redcurrant juice from fresh redcurrants in a strawberry jam instead, or an acidic type of apple and apple juice in a blackberry jam etc.

Vinegar. Vinegar is an excellent substitute for lemon juice in cooking or baking when only a small amount is needed. Much like lemon juice, it's tart and acidic. In these recipes, it can be used as a one-to-one replacement (6).

Commercial pectin helps thicken jam made with low-pectin fruits, like blackberry jam, or vegetable jelly recipes, like pepper jelly. It comes in powder or liquid form, but the former is the most common. Add powdered pectin to the fruit juice, chopped fruit, or strained purée before heating the jam mixture.

Here are some ideas so that you can see what I am talking about: Ginger is one of those spices that seems to go with everything, so it can be a good place to start. Strawberry goes really well with lavender, basil, cracked black pepper or rosemary. There is so much one can do with apricots.

The butter prevents the jam from foaming while you're cooking it - the foam is unattractive and spoils the appearance of the jam. Adding a little butter eliminates this problem."