Recipe yields 5 half-pint jars.

PREP FOR CANNING

• Prepare the calcium water: Combine ½ teaspoon calcium powder (from the small packet in the box of Pomona’s pectin) with ½ cup water in a small jar. Screw on a lit and shake until well-combined. You'll have more than you need for this recipe. Store the excess in the refrigerator for use in making additional jam or jelly recipes.
• Wash the jars you'll use in hot soapy water, making sure clean jars are free of nicks in the rim, which could impede sealing.
• Wash the lids and rings in hot soapy water. (If you're using non-Ball brand lids, prepare as suggested by manufacturer.)
• Place empty jars in a canning pot with enough water to cover by an inch or two, cover pot, and set on high heat. It can take awhile for the water to heat, so get it started before you begin making the recipe.

MAKE THE JAM

• Wash and dry loquats; remove the seeds, seed membrane, and blossom end of the fruit using a paring knife or simply your fingers.
  10 cups loquats
• Process loquat pieces in a food processor to make a pulp. Alternatively, cook the loquat fruit down to create a pulp. Put the prepared loquat halves or pieces into a pot with about a half cup of water. Cook on low to medium heat until the fruit is soft and mashable. 
• Measure 4 cups of loquat pulp into a large saucepan with the lemon juice and calcium water, and bring to a full boil over medium-high heat.
  2 tablespoons lemon juice, 4 teaspoons calcium water
• Meanwhile, in a separate bowl, combine the sugar with 1 tablespoon pectin powder (the large envelope) until thoroughly combined.
  1 1/2 cups granulated sugar, 1 tablespoon pectin
• Bring mashed loquats to a full boil. Add sugar mixture, stirring vigorously for a couple of minutes to dissolve the pectin. Return to a boil, boil for one minute, and remove from heat.

CANNING THE JAM

• Remove the empty jars from the canner, draining the water back into the pot.
• Ladle hot jam into half-pint jars to within a quarter inch of the rim. A canning funnel makes this easy.
• Wipe jar rims to remove any jam that may have spilled. A clean rim is essential to a good seal.
• Set jar lids in place. Screw bands on finger tight.
• Use canning tongs to gently submerge jars into the hot water bath. Be sure to place a wire jar rack in the bottom of the pot to prevent the jars of peach jam from sitting directly on the bottom. Water should cover the top of the jars by an inch or two. The water will cool somewhat in reaction to the addition of the jars. Return the water to a low boil and then set the timer.
• Process in a boiling water bath for 10 minutes. Add a minute to the boiling time for every 1,000' above sea level.
• Remove jars to a sturdy surface covered with a dish towel and allow to cool.
• Check seals. Lids should be solid and pulled down tight. (if they flex and pop, the jar didn’t seal; put unsealed jars in the refrigerator and use those first).
• Remove rings and wash outsides of jars. Store in a cool, dry place.