Generally, people make preserves, jams, jellies, and most other fruit spreads by cooking fruit, sugar, and pectin. Although cooks use various grape varieties to make grape preserves, the Concord grape is the most common variety used in making preserves. In 1940, the United States Food and Drug Administration (FDA) established standards for commercially made preserves and most home recipes reflect these standards. People use preserves as bread toppers, condiments, and flavorings in other recipes, such as barbeque sauces. Sometimes cooks combine grapes with other fruits like apples when making grape preserves.
Whereas grape jellies use grape juice, are usually clear, and free of fruit particles, preserves, jams, butters, and other spreads use the whole fruit and are thicker. Cooks usually make jams and butters with pureed fruit, but they make preserves with whole or crushed grapes, giving the preserves a chunky texture. Cooks may make preserves with or without the grape skins. Concord grapes are called slip-skin grapes because the skins slip off easily. Some of the other grape varieties, such as the muscadine, have thick, tough skins that are difficult to remove.
Most preserve recipes are similar. A cook usually puts the grape skins in one bowl and the grape pulp into a sieve over a bowl; and by pressing the pulp through the sieve, the cook removes the seeds from the pulp. Generally, cooks weigh the pulp and skins and adds the amount of sugar that the recipe suggests. The 1940 FDA standards are a 45:55 ratio of fruit to sweetener. Recipes for the home cook may vary, but typically are similar to this ratio.
After determining the proper amount of sugar for the preserves, the cook slowly boils the grape skins, pulp, and sweetener in a non-reactive metal pot until it is thick. Some recipes call for pectin, which is a thickener used in jellies and other fruit spreads. Many gourmet grape preserves feature special fruit parings, such as green muscat grapes and figs. Other popular gourmet preserves add apples or raisins to the grapes or special flavorings, such as spices or vanilla beans.
The most common grape variety is ripe Concord grapes, but some gourmet companies and home cooks expand the selection to include grapes like the Catawba, muscat, and other varieties. Where mustang grapes grow in the United States, some cooks make green mustang grape preserves. This grape is not a popular grape because the ripened grape is bitter. To make the preserves, the cook picks the immature grapes when they are pea-sized and the seeds are soft. Most recipes call for equal parts grapes and sugar to compensate for the sourness of the immature fruit.
People usually spread grape preserves on bread or toasted bread, but there are other uses for them. The thicker texture of the preserves — at least 68% solids by the FDA standards — makes it a good relish for meats. Some cooks use them as a condiment on beefsteaks, lamb chops, and pork roasts. Other people use them for desserts, such as a topping for ice cream and puddings.