You will love this classic recipe for Easy Plum Jam, made with sweet, ripe, juicy plums at the height of their season. It is the ultimate way to preserve this delicious stone fruit to enjoy throughout the coming months.
1 ½kg(3 ⅓ pounds) granulated sugar See Notes 2 and 3
1 ½tablespoon(30 ml) lemon juice See Notes 4 and 5
Instructions
To Sterilise the Jars:
Preheat the oven to 130 Degrees C (270F).Use glass jars, either new or recycled, with an airtight, metal lid. If recycling jars, ensure that the jars do not have cracks or chips and the lids are in good condition. Discard any lids that are pitted or rusted. Ensure your lids are oven safe or see our notes if they are not. (See Note 6.)Wash the jars and lids. If washing by hand, use hot, soapy water and then rinse them well. Alternatively, wash them in the dishwasher.Place jars and lids on a baking tray. Heat in the oven for at least 20 minutes. The jars and lids should be completely dry and remain very hot.
To Make the Jam:
Place 2 small plates or saucers in the freezer to chill – see Note 7.
Wash the plums and remove any blemishes. To halve the plums, start at the stem end and run a sharp knife around the plum, following the naturally occurring marking. Use the tip of the knife to remove the stones.Cut the halves in half again. If you don’t want your jam to have chunks of fruit, cut the plums into eighths.
Place the plums and water in a large, wide saucepan. See Note 8.
Bring the plums to a simmer over low-medium heat. Stir occasionally using a long-handled wooden spoon. See Note 9.
Cover the pot and cook, stirring occasionally, until the plums are soft, 15-20 minutes. At this stage, if you prefer less chunky jam, you could blend it using a hand-held stick blender. Take off the heat to do this.
Add the sugar and lemon juice. Stir frequently, with the saucepan uncovered, until the sugar dissolves.
Increase the heat and bring to a rolling boil for 5-15 minutes. You need to be vigilant at this point. Stir frequently to avoid the jam catching and burning on the bottom of the pan. Boiling time will vary depending on the size of your saucepan and the heat that you apply.
After about 5 minutes rapid boiling, turn the heat off under the jam. Spoon a small amount of jam onto a chilled plate or saucer to check if it is starting to set. I use the wrinkle test. When the jam has cooled, push it gently with your fingertip. If it wrinkles, even slightly, it is ready. If it remains liquid, put the jam back on the heat for a further 5 minutes and check again. See Note 10.
You can also use a thermometer to check for setting point. To use this method, you will need a sugar thermometer. Clip the thermometer to the side of your pan. When the thermometer reads 104C (220F) the jam is ready.
When the jam reaches setting point, remove the pan from the heat. If there is any scum on the surface of the jam, add a teaspoon of butter and stir well. It will dissolve the scum.
Let the jam stand for about 10 minutes to allow the fruit to settle. This will ensure that any pieces of fruit will be evenly distributed throughout the jam. Without standing, the fruit will rise to the top of the jar.
The jam will still be liquid when you ladle it into your jars. It can take up to 48 hours to completely set.
Stir the jam and carefully ladle it into the heated, sterilised jars. You need to be very careful. A splash or spill from hot jam would result in a serious burn. I recommend that you wear clothing with long sleeves. Additionally, this is not the occasion to have children nearby.Immediately seal the jars tightly with sterilised lids.
When cool, remove any spills from the jars and label with the date and name. Store the jam in a cool, dark place. When using the jam, always use a clean, dry spoon to avoid contamination. After opening a jar, as a further precaution, store it in the refrigerator.
Notes
Ensure your fruit is freshly picked and of good quality. Avoid fruit that is bruised or over-ripe. The plums contain pectin which aids in the jam setting. If your fruit is older, it will contain less pectin. The colour of the jam will vary depending on the variety of fruit that you use.
My plums were perfectly ripe and sweet so I used a fruit/jam ratio of 1 kilo of fruit to ¾ kilo sugar (1 pound fruit to ¾ pound of sugar). If the fruit you use is slightly unripe and quite tart you may need to use a ratio of equal weight fruit and sugar.
Do not reduce the amount of sugar. Whilst the sugar sweetens the fruit it also acts as a preservative and helps the jam to set. If you reduce the sugar, your jam may not be shelf-stable and may become mouldy.
The Australian tablespoon is 20ml or 4 teaspoons. In many other countries, the tablespoon is 15ml or 3 teaspoons. Please adjust the measurement if necessary.
Lemon juice not only balances the sweetness of the sugar, but it also contains acid and pectin which help to set the jam.
Properly sterilising your jars is an essential process to remove bacteria that could cause your preserves to spoil. Wash the jars and lids either in the dishwasher or by hand in hot soapy water, and rinse well. Do not dry them with a tea towel. Place jars and lids on a baking tray. If you are using Kilner jars with rubber seals, be sure to remove the seals before placing the jars in the oven. The dry heat of the oven would damage the seals. Boil the seals separately in a saucepan for about 10 minutes. If your lids are not oven safe, boil them for 10 minutes and allow them to air dry. Heat the jars in the oven for at least 20 minutes. When your preserves are ready to bottle, use thick oven mitts or jar tongs to remove the jars. Do not place them on a cold surface as they may shatter. I place mine on a wooden chopping board which I cover with a tea towel. Always sterilise a few more jars than you think you will need. It is better to have too many jars than not enough.
The chilled plates are used to quickly cool the jam when testing the setting point.
Always choose your widest saucepan that has enough height to enable the jam to boil vigorously. More surface area means the liquid will evaporate faster; having sufficient height means you can boil the jam at a higher heat and maintain the fresh flavour of the plums. Avoid aluminium, copper or iron pans; the acid in the fruit may react with the pan, giving the jam a metallic taste.
Do not use a metal spoon, it will become very hot. A long-handled wooden spoon is important to avoid being burnt by a splash from boiling jam.
My jam reaches its setting point about 5 minutes after it begins to boil rapidly. Boiling time will vary depending on the size of your saucepan and the heat that you apply.
Please note, the nutritional information is based on one whole jar. The nutritional information is an estimate only.