An ideal fruit for making jelly should be rich in

An ideal fruit for making jelly should be rich in Pectin and acids.
For proper texture, jellied fruit products require the correct combination of fruit, pectin, acid and sugar.
Pectin is a substance in fruits that forms a gel if it is in the right combination with acid and sugar. All fruits contain some pectin, but some must be combined with fruits high in pectin or with commercial pectin products to obtain gels.
The proper level of acid is critical to gel formation. If there is too little acid, the gel will never set; if there is too much acid, the gel will lose liquid (weep).