For the record, I use the terms jam and preserves interchangeably. The crushed fruit in jam leaves a slightly smoother consistency to the spread, whereas bite sizes pieces of fruit can be found throughout a jar of preserves. Otherwise, they are the same. (Jelly is made with fruit juice.)
The three ingredients used in preserves are fruit, sugar and lemon juice.
I slice my fruit into small pieces because I usually prefer my spreads to have the suspended fruit associated with preserves. Otherwise, when making a spread with the consistency of jam, I will crush the fruit using an old fashioned potato masher.
Either a 4:4 or a 4:3 ratio of fruit to sugar should be used when making these fruit spreads. Anything less than 4:3 may not set properly. Unless I an exceptionally sour major ingredient such as rhubarb, I stick to the 4:3 ratio so that more of the fruit taste shines through in the final product.
The lemon juices raises the acidity of the fruit which in turn helps it to set. It is possible to make spreads without the lemon juice if the fruit is highly acidic, but I usually add the lemon regardless. It's tempting to use fresh lemon that hasn't been adulterated with preservatives, and while it's possible to do so, it's recommended to use bottled lemon juice with a consistent acidity content. (Fresh lemons may vary in their acidity.) It's usually recommended to add one tablespoon of lemon juice per pound of fruit. I don't usually weigh my fruit to determine how much lemon juice is needed. Rather, I generally add one tablespoon of lemon juice for every four cups of fruit.
All three ingredients (fruit, sugar and lemon juice) are cooked in a pot or pan with a thick bottom to evenly distribute the heat and keep it from scorching. It's also important to use a large enough pot that the mixture will not bubble over the sides. Larger pots will also allow the liquid to cook down quicker. I cook over medium high and it's important to stir frequently.
This process does require a bit more time than when using boxed pectin. It typically takes about 20-30 minutes for my jam to reach the set stage. Knowing when the jam is at the set stage and ready to pour into jars is the most difficult part. If you cook the jam too long, it will become hard like candy and impossible to spread. Undercooked jam will be more like syrup. There's really no remedy for overcooked jam but undercooked jam can be put back on the stove and cooked again.
To test your jam to see if it is at the set stage, put a small bit on a spoon and place it in the freezer for several minute to cool it. When cooled, the jam should stay put, even when the spoon is turned side ways.
Skim off and discard the foam that forms on the top of the pot of jam.
With this basic recipe of 4 parts fruit, 3 parts sugar and 1 Tablespoon of lemon juice and a little time at the stove, its fairly simple to make jam and preserves which can then be jarred and frozen or processed in a hot water bath canner.
Rhubarb Jam
4 cups rhubarb
4 cups sugar
1 Tablespoon Lemon Juice
Cut the rhubarb into bit sized pieces and then add the sugar. Allow rhubarb and sugar and allow to set until the juice is extracted from the rhubarb. (You can leave it set for up to 24 hours, which is recommended in some recipes, but I have found that 1 hour is sufficient.)
Add the lemon juice and cook on the stovetop using medium-high heat until the fruit reaches the gel stage. I like to use my hand blender and puree the fruit once it begins cooking so that I do not have chunks of rhubarb in my final product.
Tip: I have found that rhubarb is easier for me to cut up using my kitchen scissors. I have less "strings" from the rhubarb and a nice, clean cut.
Strawberry Jam
4 cups strawberries
3 cups sugar
1 Tablespoon of lemon juice
Cook all three ingredients on the stovetop until a gel stage is reached. I like to slice my strawberries and then use a potato masher to mash about half of them. This gives me some suspended fruit in the final product while rendering the jam still spreadable on toast or biscuits.
Skim off the foam that accumulates on the top of the jelly. Ladle into jars and process or freeze.
