Making guava jam is a fairly simple task that requires guavas, water, sugar and lime or lemon juice. It takes about one hour and 15 minutes to make guava jam.
Start with 12 very ripe guavas. Cut the guavas into 1-inch cubes and place in a saucepan with enough water to cover the fruit. Cover the pan and cook over medium heat until the guavas are tender. This will take about 30 minutes. Allow the fruit to cool, then cover a bowl with muslin or cheesecloth and pour the fruit onto the cloth, catching the liquid in the bowl.
Tie the cloth around the guava and allow them to drip into the bowl for about four hours. After four hours, squeeze the cloth to gather any remaining juice from the fruit, then discard. Measure the liquid that has accumulated in the bowl. For each cup of liquid, add 1 cup of sugar and 1 tablespoon of lemon or lime juice to a saucepan. Add the juice to the saucepan and bring to a boil, then lower the heat and cook, stirring constantly, until the mixture thickens and sticks to the spoon.
Once the guava jam has thickened, let cool for 30 minutes. Pour the jam into jars and seal.