Jam is a fruit preserve cooked in sugar. Its composition and preparation is different from jelly or jam.
Although the proportion of fruit and sugar varies depending on the type of jam, the ripeness of the fruit and other factors, the usual starting point is that it is in a 1: 1 ratio by weight.
When the mixture reaches 105 ° C, the acid and pectin of the fruit react with the sugar, making the mixture solid when it cools. For the jam to form, it is important that the fruit contains pectin.