Jam, in my opinion, is fruit candy. The fruit is boiled with pectin until it thickens. Then it is boiled in a hot water bath to seal in the canning jar.
Pectin is a natural carbohydrate found in fruits and
vegetables. Apples and citrus are the main fruits used to produce commercial
pectin. After juicing the fruit, the leftovers are dried then sent to pectin
processing plants. Then we use it to make jam. When pectin is mixed with sugar
and acid it will form a gel. The right conditions must be attained.
My Ball Blue Book has all the recipes for
preserving food. I use it for proportions of fruit, sugar, acid (either lemon
juice or powdered citric acid) and pectin. One thing I always had trouble with
was getting jam to setup. I used many jars as syrup. Through more reading about
making jam, I discovered that pectin the best gelling point at 220°F. However, it
needs the presence of sugar and acid as well.
I did go down a pectin rabbit hole and it got fairly sciency. So now what about that marmalade…
Marmalade is a fruit preserve most commonly made from citrus fruits. Some of the first references to marmalade like fruit paste was from a collection of Roman recipes compiled in the 1st century AD. It was made with quince and honey. It wasn’t until the late 1600s that oranges were directly referred to in an English cookbook. It was referred to as Marmelet of Oranges. The early 1700’s brought the first printed Orange Marmalade recipe.
Any citrus can be used. Of course, the more tart the fruit the more tart the marmalade. Orange marmalade does not require adding any pectin. The pith is full of it. The recipe I use calls for thinly slicing the oranges and a couple of lemons. I use a mandolin for slicing, then quarter the slices with a knife. Toss the cut-up citrus into a large pot and cover with water. Then heat the mix to a simmer and cook for 10 minutes or so. Cool to room temp and refrigerate for 12-24 hours. This step softens the peel and renders more pectin into the water. The next day the mixture will be somewhat opaque.
Next up is reheating the oranges, adding sugar and boiling until it is nearly 220°F. I start testing the marmalade when it gets up to about 215°F. I keep a small bowl inside a bigger bowl of ice. Drop a small spoonful of the mix into the small bowl wait until it cools and see how thick it is. When it is thick like jam it is time to can. I make 1-pint jars and process for 10 minutes in boiling water bath.
Orange Marmalade
2 lemons
12 oranges
6 cups sugar
Wash the lemons and oranges. Thinly slice the lemons and remove any seeds. Cut the slices into quarters and place them in a large, wide pot.
Thinly slice the oranges and remove any seeds. Cut the slices into quarters. Use less or more oranges as needed to measure out to 8 cups. Add the oranges to the pot. Add enough water to just cover the citrus.
Bring the pot to a simmer and cook for 10 minutes. Remove from heat and cool to room temperature. Cover and refrigerate overnight, 12-24 hours.
Return the pot to the stove and heat to a boil over medium heat. Place a candy thermometer in the pot to monitor the temperature. Add the sugar a few cups at a time stirring between additions. Stir until all the sugar has dissolved.
Keep the marmalade at a steady boil. Start testing for thickness after the mixture has reached 215°F. Once the desired thickness is reached turn off the heat.
For canning, pour the marmalade into pint jars, wipe the rim, place the lid and ring on the jar. Hand tighten and process in a boiling hot water bath for 10 minutes. Remove from the canner and cool on a cooling rack to room temperature. Check that the lids are sealed and remove the rings. Store in a cool dark cabinet.
Yield: 5 pints
