With any preserving recipe, don’t try and adjust the proportions or timing, your jam may not set or seal properly.
8 clean 250-mL mason jars
8 two-piece closures, new
1 boiling water canner or a stock pot that is at least 3 inches deeper than the jar height
1 canning rack/lifting rack (for your pot)
1 canning jar lifter (optional but handy)
8 cups strawberries (about 3 ½ lbs)
7 cups granulated sugar
4 tbsp lemon juice
1 pack regular powdered fruit pectin (49g-57 g)
Place mason jars onto the rack in pot and fill pot with cool water that reaches the top of the jars. Cover and bring the water to a simmer but do not boil. Turn the heat off, jars will stay hot.
Set the screw bands of your closures aside to remain cool. Put the lids in a small pot and bring water to a simmer. Then set that aside off the heat.
Measure 7 cups sugar into a bowl to have it ready to add to jam.
Hull strawberries. In a casserole dish, make a layer of strawberries and crush with a potato masher. Keep going until you have 5 cups mashed strawberries. Transfer them to a large pot.
Add lemon juice and powdered pectin to the crushed strawberries. Bring the mixture to a rolling boil and wait for the pectin to dissolve. Add the sugar all at once and bring back to a full, rolling boil, stirring constantly. Keep at a rolling boil for 1 minute.
Remove from the heat and skim the foam from the surface with a slotted spoon.
Remove a jar from the canner — you don’t need to dry it — and using a canning funnel or ladle fill with jam leaving about ¼ -inch space at the top. Slide a non-metallic utensil in the jar a couple times to get rid of any air bubbles. Add extra jam if needed.
Wipe the top of jar and the threads with a clean cloth.
Using tongs remove a lid from the hot water. Place on top of the jar and twist on the screw band. You don't have to screw it on very tightly.
Repeat with the rest of the jars.
Place the jar back into the canner or stock pot onto the canning rack. Make sure jars are covered by a minimum of 1-inch hot water.
Put the lid on the pot and bring the water to a boil over high heat. Process (boil rapidly) for 10 minutes. Do not start the 10 minutes until the water is fully boiling.
At the end of 10 minutes turn off the heat and let the jars stand for 5 minutes. Remove the jars with tongs or your canning jar lifter (do not tilt them) and place them on a kitchen towel. Allow to cool for 24 hours without being disturbed.
After 24 hours check the lids. The center of the jars should be concave to show a proper seal. They will not move in the centre.
If your jar lids are convex in the centre or “pop” when you press them, the jam is still good. Just make sure you store it in the fridge.