3 Qts cooked and pureed guava goo
water to thin as necessary
3/4 C lemon juice (1 Tbsp per cup of mashed fruit)
1/4 C calcium water (1/2 tsp to 1 tsp per cup of fruit)
3 T Pomona pectin (1/2 tsp to 3/4 tsp per cup of fruit) (1 box, here)
1 1/3 C allulose
1 T ground ginger
2 tsp cinnamon
3/4 tsp white pepper

Wash the guavas and cut them in half.  Using a spoon, scoop out the insides into a deep vessel.  Toss the green rind in the green waste.  The guavas will oxidize, so if you must stop in this process, cover them with lemon water and place plastic wrap directly on top of the pulp (like you would a pudding).  Once all the fruit has been processed, place it in a large pan, add more water to cover, and cook until tender.  Working in batches, blend the fruit and cooking liquid in a food processor or heavy-duty blender.  Measure the fruit puree and adjust above ingredients as necessary. 

Wash the jars, rings, and lids.  Bring the empty jars to a boil in a canning pot, and leave on simmer as you make the jam.  Lids should go in a small saucepan with water to cover and kept hot, but not boiling.  

Mix the pectin with half of the allulose and set aside.  Combine all of the rest of the ingredients in another large saucepan and bring to a full boil.  Add the pectin-allulose mix and stir vigorously for 1-2min to dissolve the pectin while the mixture returns to a full boil.  Remove from heat.

Pull up the canning rack from the pot and suspend over the water.  Bring the water below to a boil again while you fill the jars.  

Fill jars one at a time (one out, one in) with 1/4” headspace.  Wipe the rim with a damp cloth, top with lid and screw ring on fingertip tight.  When all the jars are full, lower the rack back into the now boiling water, making sure it covers all the jars by at least 1”.  Boil for 10 minutes.  Turn off heat, pull up the canning rack and place the jars on a dry towel where they won’t be disturbed as they cool.  Listen for the happy canning music of the lids sucking in.  :-D

When fully cool, gently press on any raised buttons.  If they don’t indent and stay that way, open the jar, checking the rim of the jar for chips or other matter preventing a good seal. The jam can be resealed and reprocessed in another hot water bath, or consumed as refrigerated jam within a few weeks.

Basic recipe amounts from Pomona Pectin