Things You'll Need
Concord grapes (amount depends on pectin brand)
Sugar free sweetener
Canning jar, lids and rims
Sieve, cheesecloth, or jelly strainer
Lemon juice (optional)
Jam is a lengthy process, but for many who prefer to make their own food products it is a rewarding and fun activity. Most homemade jellies are made with a store-bought pectin to allow for proper setting; these pectins require a lot of added sugar, usually more sugar by volume than actual fruit. An alternative to this sugar-high is is no-sugar added pectin, sugar free sweetener and the acceptance of a less-sweet and more natural tasting jam or jelly. Concord grapes are naturally sweet, thus sugar-free concord jelly is not a sacrifice when compared to full sugar jelly.
Wash and cook your grapes. Jelly is completely smooth and clear of any bits of fruit or seed; it is made from fruit juice, while jam is made from fruit flesh.
Smash the grapes with a potato smasher or whirl them through the food processor. Transfer them to a heavy bottomed soup pan. Bring them to a boil, stirring often. Reduce the heat and let it simmer for 10 minutes.
Extract the juice from the cooked grapes. Strain them in a sieve, in a cheesecloth suspended above a bowl, or in a jelly strainer. The grapes must be completely smashed before you strain them or there will not be enough juice collected. While the grapes are straining, wash and prepare your jars.
Sterilize the canning jars for a traditional canning method. Wash the jars, lids and rims in soapy water and sterilize for 10 minutes in your canning pot at a full rolling boil. Remove the sterilized jars and line them up on a clean towel. Keep the lids and rims submerged in a small saucepan covered in hot water until ready to use. If you are making freezer jam, just wash your freezer jam containers.
Choose "no sugar added" pectin. Both Ball and Sur-Jell brands offer a no sugar added boxed powder pectin. Pomona brand pectin can also be used in sugar-free jams and jellies as it is a pectin that allows the jam maker to create custom ratios. Read the instructions on each individual pectin box, as every brand is different in the amount of fruit needed per pectin packet. For jelly (grape included) it will list the volume of fruit juice needed based on the individual pectin you have selected.
Measure the sweetener. If you prefer the less sweet and natural flavor of the grape juice, forgo sweetener. However the flavor will be less pronounced and slightly bland. Most sugar-free jams use either 1 to 2 cups of Splenda, or a sugar texture substitute. Or, 2 to 3 tbsp. of lemon juice can also be used to liven up the flavor without adding sugar.
Combine the strained juice, pectin and sweetener (or lemon juice) in the same pot you cooked the grapes and bring it to a boil. Once a full rolling boil is reached (boiling while stirring), boil for 1 minute. Then remove the pan from the heat.
Strain off any foam that has accumulated on the surface. Test the jelly by dipping one spoonful in a cold glass of water, if it thickens to jelly consistency, it is ready. If it does not, stir in more pectin and boil for another minute.
Ladle into your prepared jars. Wipe the rims with a clean cloth. Place lids. Lightly screw on the rims and process in the water bath. Most water canning processes take 10 minutes submerged; check the directions inside of your pectin box to note time changes with elevation.