This Orange Marmalade recipe is made with ordinary oranges and lemons, and it’s as unfussy as it is delicious. It follows the "old fashioned" technique of sitting in a pot overnight, and every spoonful will make your morning toast sparkle.
Cut oranges and lemons in half crosswise, then into very thin half-moon slices. Discard any seeds. In a large stainless steel pot, add the sliced oranges, lemons, and any accumulated juices.
Add water and bring the mixture to a boil, stirring often. Remove from the heat and stir in the sugar until it dissolves. Cover and let stand overnight at room temperature.
The next day, bring the mixture back to a boil. Reduce heat to low and simmer uncovered for 2 hours. Turn heat up to medium and boil gently, stirring often, for another 30 minutes.
Skim off any foam that forms on the top. Cook the marmalade until it reaches 220 degrees (you must hit this temperature for the natural pectin to gel with the sugar).
To test if the marmalade is ready, place a small amount on a plate and refrigerate it until it's cool but not cold. If it's firm (neither runny nor hard), it's ready. It will be a golden orange color. If the marmalade is runny, continue cooking it; if it's hard, add a bit more water.
Pour the marmalade into clean hot mason jars; wipe the rims thoroughly with a clean damp paper towel, and seal with the lids. Chill in the refrigerator. It may take 24-48 hours for the natural pectin to set up properly.
Oranges: This recipe is made with regular seedless oranges. You can definitely substitute Seville oranges if you can find them. They are only in season from the end of January to mid-February, but they have an intense flavor that is ideal for marmalade.
Yield: This recipe makes about 3 quarts (96 ounces) of marmalade.
If using 1/2-pint (8 ounce) jars, you'll need 12.
If using 1 pint (16 ounce) jars, you'll need 6.
If using the tiny jelly jars (4 ounce), you'll need 24.
Storage: Store covered in the refrigerator for up to 1 month.
Freezer: Freeze for up to 3 months. Thaw overnight in the refrigerator.
Cold-plate test: To test if your marmalade is ready, spoon some hot marmalade on to a plate and put it in the freezer to chill, or spoon some over an icy cold plate fresh from the freezer. If the mixture wrinkles slightly when you draw a spoon or finger across it, it has reached the setting point. Your marmalade is ready to go! If not, keep boiling and make sure the temperature reaches 220 degrees.
Set-up time: Orange marmalade takes 24-48 hours for the natural pectin to set up completely. If your marmalade is still a little runny looking when it cools, check again in a day or two.
Pectin: While many jam and jelly recipes require added pectin, you don't need to add any to this marmalade. Pectin is naturally concentrated in the pith of the orange (the bitter white part under the peel). This recipe coaxes out that natural pectin by letting the citrus soak overnight and then boiling it rapidly until enough water has evaporated that the mixture can reach 220 degrees.
Agave nectar: Agave cannot penetrate and sweeten the peel as well as sugar can. When I tested it, the consistency was fine, but the rind tasted like raw rind. I don't recommend this substitution.
Low sugar: I haven't tested low-sugar/alternative sweeteners in this recipe other than agave as listed above. I recommend seeking out recipes from experts in that area.
Canning: If putting up for storage, use a hot water or steam canner to properly seal lids according to canning instructions. Otherwise, refrigerate and use within the month. Or, freeze for up to 3 months.
Slow cooker marmalade: While it is technically possible to make marmalade in your slow cooker, it really depends on the power of your appliance. I no longer recommend that method because it isn't reliable enough.
Instant pot marmalade: Even with an overnight soak, the IP doesn't break down the rind sufficiently. I don't recommend this method.