Add the fruit and sugar to a pot or deep pan. Set on the stovetop, turn the heat to medium-high and bring to a boil. Boil for 7 minutes.

Lower the heat to medium-low and keep cooking, stirring frequently, for an additional 35 minutes or so.

Use an immersion blender or a potato masher to mash the fruit. Mash it all the way or leave large chunks. It’s up to you.

Add the juice of one lemon and 5-6 lemon seeds. Stir them in and keep cooking until the jam gels (for me it was about 45 additional minutes but this might change depending on how juicy your fruit was to begin with).

To check the thickness of the jam you can use the spoon test. Scoop a little bit of jam into a spoon and set on the kitchen counter to cool for five minutes. Then add the jam back to the pot and as it leaves the spoon you’ll be able to measure how thick it is. Just remember that the jam will thicken a little further as it cools completely in the jars after canning it. Once the jam is ready, turn off the heat.

To your water bath canner, add enough water to cover the jars by at least an inch. Set the canner on the stovetop and turn the heat to high. Bring the water to a boil.

Wash the jars, lids, and rings well with hot water and dish soap.

Pack the jars with the hot jam, leaving ½ inch of headspace. Use the bubble remover to remove bubbles by scraping it along the walls of the jar from the inside. Use a damp paper towel to clean the rim of the jar. Center the lid and close the jar with the ring finger tight.

Set the jars on the rack of the water bath canner and lower them into the boiling water. Cover the canner and process half-pint and pint jars for 15 minutes (remember to adjust processing time according to the table in the notes if you live above 1000 feet in elevation).

When processing time is up, uncover the canner and turn the heat off. Let the jars rest in the hot water for five minutes before you remove them.

Use the jar lifters to remove the jars from the canner. Set them on a kitchen towel on the counter to cool completely overnight.

Before storing the jars, make sure that they all sealed by pressing on the center of each lid. If there is no movement there it means that the jars have sealed (if you have a jar that didn’t seal you can store it in the fridge and use it first). Wipe your jars and remove the ring before you store the jars in the pantry (I remove the ring because it sometimes rusts over time and makes it hard to open the jar down the road and because it’s easier to monitor what’s happening in the jar without the ring in the way). Pineapple jam should last 12 to 18 months in storage.