A good recipe for loquat jam uses 12 cups of seeded, halved loquats, 6 cups of sugar and 6 cups of water. Put everything into a large pot, then boil for five minutes. Reduce to medium-low heat, and simmer for between 2 and 2 1/2 hours. The loquats turn from a bright yellow color to dark amber when done. Most of the liquid evaporates. Stir the jam occasionally, and use an immersion blender to smooth out any lumps.
When the jam is cooked, ladle it into half-pint canning jars. Wipe the rims clean, put the rings and lids in place, and allow the jars to sit and self-seal. Label and date the jars, and store them on the shelf. Once open, loquat jam needs to be refrigerated. This recipe yields 9 half-pint jars.
Loquats are tangy, slightly sweet fruits with large seeds. The most time-consuming chore is removing the seeds, which are not edible. Blanching the fruit makes this chore easier, and it helps release the juices. It also minimizes the loquat's distinctive scent. The skins are thin and break down during the cooking process, so there is no need to peel them.
If harvesting your own loquats, pick when they are yellow but have no greenish tinge. Orange-colored loquats tend to be overripe and may not be as flavorful. They grow in clusters, and sometimes, it's just easier to harvest the entire cluster rather than the individual fruits.