Prepare the muscadines: Start by washing the muscadine grapes thoroughly to remove any dirt or debris. Place them in a large pot and gently crush them with a potato masher or the back of a spoon to release their juices. Pour in 1 cup of water and bring the mixture to a boil over medium heat. Let it simmer for about 10 minutes, stirring occasionally, until the grapes are soft and the skins have released their color and flavor.
Extract the juice: Once the grapes are softened, pour the mixture through a fine mesh strainer or cheesecloth into a clean bowl, pressing down to extract as much juice as possible. For a clearer jelly, avoid pressing too hard — just let it drip naturally for a few minutes. You should end up with about 3 cups of muscadine juice.
Prepare the jelly mixture: Pour the juice back into a clean pot and stir in the lemon juice and fruit pectin. Mix well to dissolve the pectin completely. Bring the pot to a rolling boil over medium-high heat, stirring constantly to prevent sticking.
Add the sugar: Once boiling, add the sugar all at once and stir until it’s fully dissolved. Add the butter if you want to minimize foaming. Continue to cook over high heat, stirring constantly, until the mixture reaches a full, rolling boil again that cannot be stirred down. Boil for 1 minute exactly, then remove the pot from heat.
Test the jelly: To check if your jelly has set, place a small spoonful on a chilled plate. Wait a few seconds, then push the edge with your finger — if it wrinkles, it’s ready. If not, boil for another 30 seconds and test again.
Jar and seal: Quickly skim off any foam from the surface. Ladle the hot jelly into sterilized half-pint jars, leaving about 1/4 inch of headspace. Wipe the rims clean, apply the lids and bands, and process the jars in a boiling water bath for 5 minutes to ensure a proper seal.
Cool and store: Carefully remove the jars and let them cool undisturbed for 12–24 hours. Once cooled, check the seals — the lids should not flex when pressed. Store sealed jars in a cool, dark place for up to a year.
