A technique to produce a nice and natural colored sweets, such as kamias / balimbing prunes, pineapple candy, mango candy and even home made sugars, muscovado and coconut sugar.
The technique is simple and just involves the proper combination of time and temperature. Cook it as fast as possible at peak of manageable heat. Half kilo pineapple plus half kilo white sugar when cooked for 30 minutes is going to produce bright yellow colored candies. On the other hand, the longer time it takes, the more brown and ugly it becomes. I experienced cooking the same mixture for over two hours. I produced dark brown candies in the end.
The pineapple flesh is yellow and so the candy version should be yellow too. Brown is fine either – as brown apple juice and red banana ketchup. Color resembling the origin is more acceptable though.
The other method which I have never tried is the choice of cooking vessel. I want to try it but I have a little doubt.
I got a hearsay information. Cooking kamias prunes on copper casserole maintains the natural green color. If such is not available, dropping a copper coin will do. Kamias prunes I have seen and eaten are all color brown. I have never encountered any with green color. Maybe it is true or maybe it is not.
If the hearsay is true, then the brief explanation might also be. Most fruits are acidic and reacts with copper metal. The elements migrated to food sample are able to intercept reducing sugars which are responsible for browning.
Various literature tell the reverse. Contact of food with copper plates and variants speeds up the browning reaction.