Guava jam is just enough of a hassle to make that I do it only because I can't find a guava jam for sale that I like. Commercial guava jam is usually too sweet for me and doesn't have a lot of flavor. Below are two low sugar versions, one using Sure-Jell Low Sugar and one using Pomona's Pectin. When using Sure-Jell you have to use the minimum amount of sugar stated in their directions to get it to thicken and gel properly. Pomona's Pectin works differently, which is why that recipe has even less sugar. Pomona’s can be used with alternative sweeteners or no sweetener at all - find out more in the Pomona’s Universal Pectin FAQ. If you would like to make a raw, uncooked guava jam, try Freezer Jam with Pomona’s Pectin.
These recipes usually yield 2 - 3 pints of jam (depends on how much water evaporates off, how juicy the guavas are, how much foam gets skimmed off…). I clean 4 pints worth of jars just so that I can be sure I have enough jars. So: 4 pint jars, or 8 half-pint jars, or 16 quarter-pint jars, or a combination of jars that adds up to 4 pints. 1 cup is roughly 1/2 pint. I’d rather put away clean, empty jars than try to hustle and get more jars cleaned. If I’m not planning to hot-water bath can the jam, I also re-use empty glass jars from nut butter, salsa, etc. Again, that’s only if I’m not going to can the jars - they will go in the fridge after cooling. They can explode if you try to do a hot-water canning bath! I just do a soap and water scrub for those. If I am planning to can, I go ahead and steam or boil the canning jars, since I’ll be heating up a big pot of water anyway.
Sure-Jell Low Sugar
1 packet Sure-Jell Low Sugar (pink box)
4 cups guava pulp
1 cup lemon juice
1/2 cup water
3 cups white cane sugar
Mix 1/4 cup of the sugar with the pectin. Combine guava pulp and lemon juice in a large pot, then stir in the sugar-pectin mixture. Bring to a rolling boil, stirring constantly. Stir in the remaining sugar, bring back to a rolling boil, and boil for 1 minute. Remove from heat. Skim off any foam. Fill jars to within 1/8" of the top. If hot water bath canning, process for 10 minutes.
Pomona's Pectin
3 teaspoons Pomona's Pectin
3 teaspoons calcium water (prepared according to directions in Pomona's Pectin box)
4 cups guava pulp
1 cup lemon juice
1/2 cup water
2 cups white cane sugar
Mix the sugar and pectin in a small bowl. In a large pot, combine guava pulp, lemon juice, and calcium water. Bring to a rolling boil, stirring constantly. Add the sugar and pectin mixture and bring back to a rolling boil, continuing to stir constantly, and boil for 1 minute (still stirring!). Remove from heat. Skim off any foam. Fill half-pint jars to within 1/4" of the top. If hot water bath canning, process for 5 minutes.
VARIATION: Guava Passion
3 teaspoons Pomona's Pectin
3 teaspoons calcium water (prepared according to directions in Pomona's Pectin box)
3 cups guava pulp
2 cups unsweetened lilikoi (passionfruit) juice
1 1/2 cups white cane sugar
Mix sugar with pectin in a small bowl. In a large pot, combine guava pulp, lilikoi juice, and calcium water. Bring to a rolling boil, stirring constantly. Add the sugar and pectin mixture and bring back to a rolling boil, continuing to stir constantly, and boil for 1 minute (still stirring!). Remove from heat. Skim off any foam. Fill half-pint canning jars to within 1/4" of the top. If hot water bath canning, process for 5 minutes.
NOTES
Making guava pulp: wash guavas, trim off any stems, and cut into quarters. Check for unwanted visitors to discard. Either blend the remaining guava pieces (skin and all) in a blender and then mash through a sieve or food mill to remove seeds, or cook with a little water until soft (about 1/4 cup per batch, just so the fruit won’t stick to the pot and burn) and then mash through a sieve or food mill to remove seeds. During guava season, I clean and prepare pulp as I get guavas, pack it into plastic zip-top bags (I measure out the pulp as I fill the bags and label the bags with the amount) and then store in the freezer until I'm ready to make jam. Freezing and thawing also makes the pulp easier to mash and strain!
To juice lilikoi (passionfruit) see my recipe for low-sugar lilikoi jelly.
When something is labeled "low sugar" it's worth asking what a normal amount of sugar is for that item. In this case, a "regular" amount of sugar could be 4 - 5 cups per batch. Take into account how much you think a single serving of jam is. If you are eating just one teaspoon, that’s not much sugar. If you like to put a nice thick layer onto a slice of toast, that may be more sugar than you really want. While I have been able to reduce the amount of sugar, Pomona's Pectin has information on how to use alternatives to white cane sugar including honey, agave, stevia, and Truvia, as well as making a jam or jelly with no added sugar.
The National Center for Home Food Preservation has excellent information on hot water bath canning at home, as well as information on adjusting processing time for higher elevations.