Making and canning grape jam is easy to make and unlike it's cousin, grape jelly, it's hard to find on grocery store shelves. This is one jam that makes you glad that you can can! And if this is your first canning experience being able to make something you can't get in every grocery store will keep you canning for years to come.
How to Make and Can Grape Jam Step by Step:
You can make grape jam from red, white or purple grapes. I used about 14 and 1/2 pounds of red seedless grapes to make four batches of jam. To make one batch you'll need 3 and 1/2 pounds.
Wash your grapes.
For one batch of jam measure out 9 and 1/2 cups of grapes. I put them into my food processor to chop. You can cook the grapes and run them through a strainer to remove the skins if you prefer, but I didn't bother, I don't notice the skins in the final product. I'm more of a cook than a chef. I like my food to look pretty but my main focus is taste. (If you use purple or black grapes you might have to run them through a strainer if they have seeds.)
My food processor "runneth" over. You can see the overflow. So be sure not to overfill the food processor. I should have put in about 4 cups at a time.
This is the consistency you're looking for.
Go ahead and get your jars ready and put your canner on because things will move fast once you put the jam on the stove. Wash your jars.
Wash your lids.
Wash your rings.
Place your canning jars in the oven. I let them heat up to 350 degrees to sterilize them for ten minutes then turn the oven to 200 degrees to keep them warm.
Place all your lids and rings in a small pot. I bring this pot to a boil briefly and then turn it to low to keep it hot. This is to loosen the seal so you will have a good seal between the lid and the jar.
Put your grapes in a pot, add 2 and 1/3 cup water to them and simmer for about 10 minutes.
Meanwhile measure out your pectin and sugar. For this recipe I used the Pectin Calculator on Ball's website. Although they say at the bottom to not work in amounts over 5 pints I always stretch it just a bit. I usually can jam in quarts. I have three hungry boys, so I have to work in large quantities. My goal here was 14 cups or 3 and 1/2 quarts. You can see I'm making a double batch in two separate pots (see above picture) so my goal was to fill 6 quart jars. (I only make two batches at a time. To make the other two I would simply repeat the process.) I use the low-sugar pectin from Ball. Here I added 8 tablespoons. I always use a little less pectin than Ball requires because I think most of their recipes require too much. It's a matter of personal preference - if you want your jam stiff then use more pectin. Add the pectin slowly or it might clump. Also, you want to stir constantly. After you add your pectin bring your jam to a boil that you can't stir down. Don't walk away.
I use the low-sugar pectin so I don't have to use a lot of sugar although I still use some. Here I used 3 and 1/4 cups sugar per batch. Bring the jam back up to a boil for about one minute.
Now you're ready to place the jam in your jars.
Check your headspace. On this jam you should have 1/4 inch headspace. You can see here that I have a little foam on the top of my jars. You can stir in a bit of butter (1/4 t) if you want to reduce your foam. I follow a plant based diet so I don't add butter. The foam does not bother me.
Remove the air bubbles from the jars. Although it seems I can never get them all out, this handy tool helps. The other end of the air bubble remover helps measure the headspace.
Wipe off the rims of the jars so that you can get a good seal.
Remove the rings from the pot. This tool has a magnet on the end and makes it easier to grab the rings and the lids. Also, if you place the lids and rings in the pot inside each other like you see I've done in the picture this will prevent the tops from sticking.
Place the lids on the jars.
Place the rings on the jars and tighten “finger tight.” Finger tight means not too tight and not too loose. Just tighten them as far as they will go without forcing them. You can see I only got 5 quarts and a little bit. It never works out exactly. I always just make sure I have one extra jar prepared just in case.
Place the jars in the canner.
Bring the water to a boil and start the timer. Grape jam should be processed (boiled) for 10 minutes, adjusting for altitude. You can find adjustments for altitude here. To look up your altitude go here. Turn off the heat and let the jars sit in the water for about 5 minutes. I love my new canner made by Victorio - you can see when the water starts to boil without having to lift the lid. It also has two steam vents in the lid.
Then remove the jars from the canner.
Let your jars sit and cool for at least eight hours. Remove the rings. If the rings stay on and the lid fails (becomes unsealed) while the ring is on, the lid may reseal itself. However, bacteria has already invaded the jar and the food should not be eaten; with the ring left on there is no way you will know about the resealing. If the rings are off the lid has no pressure to reseal itself so if the lid seal fails then you’ll know and you can throw that jar out. Label and put away.