Points to Remember in making Marmalade: -
2. The pips and white membrane contain a lot of jellying substance called "pectin," hence the reason for soaking beforehand, before discarding them, in order to extract that jellying property.
4. It is important in making Marmalade of any kind to cook the fruit and water for at least 3 to 4 hours before adding the sugar, otherwise the rind will be tough and hard, and no amount of cooking will soften it.