Crush the grapes with a potato masher. This will help speed up the extraction process.
Bring the grapes to a boil and then reduce heat to a simmer.
Cover the pot and simmer for 10 minutes.
Stir occasionally.
In the meanwhile, sterilize jars and caps (for details refer to post section on THE PREPARATION).
Pour the cooked grapes, in a jelly bag or cheesecloth-lined strainer. Allow to drip for a couple of hours.
Making the jelly:
Combine the extracted grape juice and sugar in a large heavy-bottomed pot.
Over high heat, stir together until the mixture comes to a boil.
Add the pouch of Certo and continue to stir the boiling mixture for 1 minute.
Remove the pot from the heat.
Stir and skim the foam for approximately 5 minutes.
Ladle the jelly immediately into the hot sterilized jars. Leave ¼ inch of headspace. Place a sterilized lid and screw on the top.
The final part is processing the jars in a boiling water bath for 5 minutes.
When you hear the seals of the jar lids popping, you'll know you've done a good job!
Notes
Please keep in mind that the nutritional information provided below is just a rough estimate and variations can occur depending on the specific ingredients used. *recipe adapted from Certo