What you Need:
Sterilized half pint jars and lids (usually 3 to 4 per batch)
Tongs and other canning accessories (optional but makes process much easier)
4 cups of mashed raspberries
1 package of Pomona's Universal Pectin
1/2 to 1 cup room temperature honey, agave or sugar
This recipe is easy and straight-forward. The Pomona's Universal Pectin package contains all of the step-by-step instructions for making jams. The following steps are quoted from their website at https://pomonapectin.com/directions/ and inside each package (with 1 additional step and notes of my own as noted in parentheses).
1. Wash and rinse jars: let stand in hot water. Bring lids to simmer (in small pan of water); turn off heat; let stand in water. Wash screw bands; set aside. (I boil the rings along with the jars in water)
2. Prepare calcium water. Put 1/2 teaspoon calcium powder and 1/2 cup water in a lidded jar. Shake well.
3. Prepare fruit or juice. Measure fruit or juice into pan. Add lemon or lime juice if called for in recipe. (Raspberries don't require this. I cook my fruit for about 1/2 hour with 1/4 cup of water to allow the seeds to soften a bit. While some folks strain these out, I prefer to keep them in the jam.)
4. Add proper amount of calcium water into pan stir well. (for raspberry jam, 2 tsp calcium water)
5. Measure sugar or room temperature honey (I use 1/2 cup honey or agave) into separate bowl. Thoroughly mix proper amount of pectin powder into honey or sugar (for raspberry jam, 2 tsp pectin)
6. Bring fruit or juice to a full boil. Add pectin-sweetener. Stir vigorously 1-2 min to dissolve pectin while mixture returns to full boil. Remove from heat.
7. Fill jars to 1/4" of top. Wipe rims clean. Screw on 2-piece lids. Put filled jars in boiling water to cover. Boil 10 min. Add 1 min. more for every 1000 ft. above sea level. Remove from water. Let jars cool. Check seals; lids should be sucked down.
There are many sources of jam recipes as well as pectin sources. My personal preference is Pomona's primarily because its 2-part pectin and gelling formula allows you to reduce or even eliminate the addition of sweetener. I typically cut the addition of sweetener way back for raspberry jam to allow the natural flavor of the fruit to dominate. Pomona's is also great about identifying the fruits that require a boost in acidity level by the addition of lemon or lime juice.