Summer brings an abundance of stone fruits such as plums, peaches, and apricots. These are delicious in jams like this plum peach jam. It's also low in sugar, and made the old-fashion method without pectin in less than 30 minutes.
Place two small ceramic plates in the freezer so we can use these to test the jam later. Alternatively, you can use a candy thermometer to check the doneness of the jam.
Score an X on the peaches and plums with a knife. Then, blanch them in hot water for 3 minutes to remove the skin. Let cool slightly then peel and core them. Chop the fruit roughly so you don't have large pieces.Pro tip - Covering the fruit in a bowl with plastic wrap for 7 to 10 minutes will help the skin peel off easily.
In a heavy bottom pan, combine the fruits, sugar, salt, and lemon juice.Pro tip - If you plan to use the fruit with the skin on, let the fruits macerate in sugar and lemon juice for a few hours before cooking. This softens the blueberry skin considerably.
Cook on medium heat until the sugar is dissolved. Then, turn the heat up and let the mixture come to a boil. Let it boil for two minutes on medium-high. Pro tip - Boiling the jam is important as it releases pectin from the skin and seed in fruits.
Then, turn the heat to medium-low. The jam should still be simmering but at a low simmer, not bubbling. Use a vegetable masher to mash the fruit – so you have a smoother jam-like consistency.Pro tip - Mashing the fruit is optional, as the fruit will break down into smaller chunks similar to preserve as it cooks. However, mashing will give smoother consistency like jam.
Continue to simmer for about 20 to 30 minutes more stirring often so it does not stick to the bottom of the pan. The jam will continue to thicken as well as deepen in color as it cools.Pro tip - The cooking time will depend on the quantity of the jam as well as the heat applied to it. It's ok to cook a little longer but there must be a simmer for the fruit to release pectin.
Testing the Jam
Remove one of the ceramic plates from the freezer. Place a teaspoon of jam on the cold plate. Pro tip - The cold plate will help cool the jam almost instantly and give you a good indication if the jam is ready.
Set aside for 2 to 3 minutes. Then, test with your finger. Simply move/push the jam with your finger. If it wrinkles/crinkles it means the jam is ready. And if not, let the jam cook a couple of minutes more and test again.Pro tip - You may need to test the jam on a ceramic plate more than once or a couple of times depending on how early you start checking.
Alternatively, you can use a candy thermometer - the jam should reach 105 C / 221 F.Pro tip - I find the thermometer to be the easiest and fool-proof method to check for doneness.
Optional - Just when you are ready to take the jam off the heat add a teaspoon of butter and stir well. Butter helps dissolve foam that accumulates on top of the jam. Pro tip - You don't need more than 1 teaspoon of butter to help with the foam. It will also give you that glossy shine.
Pour the jam into warm sterilized jars leaving ¼ inch space from the top. Use a clean sterilized knife or spatula to move the jam a bit – this will remove any air pockets.
Place a piece of wax paper on the top before you place the lid on tightly. Clean the rim of the jar with a clean paper towel. Top the lid. Alternatively, use the lid with screw-on rings that come with the canning jars.
The canning process (if you plan to can the jam)
Sterilizing the jars
Sterilize 4 x 8 oz (250 g) jars by washing them in hot soapy water or cleaning them in the dishwasher with a gentle cycle. Then, place them in the oven for 20 minutes at a low 284 F / 140 C.Pro tip- I find the dishwasher does a good job of cleaning and the oven dries any excess moisture in the bottles.
Note - Leave them in the oven until you are ready to use them (you can turn the oven off). Don’t forget to wash and sterilize the bottle lids as well.
Place a rack in the bottom of a large stockpot. Fill half the pot with water. Bring the water in the pot to a boil on high heat.
Lower the jars over the rack leaving enough space between the jars.Pro tip - The level of water should be at least an inch above the top of the jars. So if necessary pour more boiling water.
Bring the water to a boil again. Cover the pot and process/simmer for 15 minutes.
Then, carefully remove the jars from the stockpot and place them on a kitchen towel to absorb any excess moisture. Cool completely. Pro tip - The hot jars are very delicate so make sure to use tongs when taking them out and place them on soft towels to prevent them from breaking.
Press the top of the lid to ensure the seal is tight – the lid should not move at all. Store in a cool dry place.
Shelf life - Homemade jams made with sugar and fresh fruit can have a long shelf life. If processed with the canning method, and stored properly in a cool dark place, a jam can last for up to 2 years. Once opened it can be kept in the refrigerator for up to 3 months
Do you need lemon juice? Almost all jams use lemon juice. Lemon is a great way to cut down on that sweetness with a citrus edge. It also prevents the sugar from crystallizing. Most importantly the lemon helps prevent any growth of bacteria when canning the jam.
How long do you cook jam? We often say low-heat slow cooking is what makes a good jam. This does not mean it takes a long time. Usually, a good 20 minutes is all it needs for about 1 kg / 2 lbs of fruit jam to reach a set point. You can start checking the jam after it has been cooking for 18 to 20 minutes.
Jam no setting - Often the reason jam does not set though reduced to half is that it has not been boiled enough. The low-heat slow cooking is what makes jam reach its setting point. If cooked too fast the liquid is reduced but without going thru the natural process of setting. So, low-heat slow cooking is the key to a perfect jam.
Over-cooked jam - It is possible to overcook jam. It is better to undercook rather than overcook a jam. Because undercooked can be cooked again, but once overcooked you have to add water to thin the jam. Note, once you add water you reduce the shelf life of the jam as well. Best to get it right the first time.
Jam done test - getting the jam off the heat is critical and often we take it off too soon or too late resulting in a runny or too thick jam. So here is an old mom's method that works great to test any fruit jam.
Place two ceramic plates in the freezer or fridge. These cool while the jam is cooking. When you are ready to test - bring the cold plate out. Put a spoonful of jam on the plate. The cold plate will instantly cool the jam giving you an indication of how much it has set. Simply put the jam on the plate from the corner towards the center. If it wrinkles it is set. Time to take the jam off the heat. If not, continue with a few more tests - every 3 to 5 minutes.
If you do have a candy thermometer on hand you can use it and take the guesswork out. I used mine for instructional videos to show the process for those who would like to use a candy thermometer.
If canning, the canned jam will stay in a cool dry place in the pantry for up to a year or even longer.
When not canned, the jam will stay at room temperature for a month or more in good weather.
You can also keep the jam in the fridge for 3 to 6 months.
Label the jar with the name and date so you know what is in and when you made it.
The nutrition information and metric conversion are calculated automatically. I cannot guarantee its accuracy. If this data is important to you please verify with your trusted nutrition calculator. Thank you