What happens when sugar is added to cooked fruit near the end of cooking process? Why sugar is added to cooked fruit near the end of the cooking process?
You need the juices from the fruit to release so the sugar can melt into it. If you add it before then the sugar will burn. In making preserves, there are only two steps, cook fruit till juices release, then add sugar and stir till dissolved.
If you are using pectin in your recipe, you want to minimize the the cooking time of the combined pectin and sugar (overcooking lowers the gelling power of the pectin). When using liquid pectin, you cook your fruit and sugar together and add the pectin at the end of cooking. If you are using powdered pectin, you cook the fruit and pectin together (so the pectin dissolves), then add the sugar at the end.
If you add lots of sugar to the fruit early (whether you are already cooking it, or before cooking), you will create osmotic pressure and draw the juice out MUCH quicker. This might be a desirable (if you want to just get the juice out and thicken it) or very undesirable (if you are trying to caramelize instead of stew the fruit).