Lots of fruits are spoiled and could be "recycled" in a verysimple way:
Just about any fruit and many vegetables can turn into Jam. Greenand overripe states of the fruits can add interestingvariations.
The fruits mass is cleaned from seed, shells and leaves and cutinto small pieces.
Sugar is added in about the same quantity as fruits: white surgarrather less, brown sugar rather more.
The mixture is stirred cooked on high flame until its concentratedenough. Consider that the consistency becomes more solid aftercooling. So test while cooking by looking at drops falling from aspoon. When they become bigger, it might be the point. If it was not,you can heat up again and go on cooing.
Then the jam is filled hot into jars with metal cover, leavingsome air on top. After closing the cover, stirr to heat up the airand open the cover quickly to let the air pressure out. Thisguarantees that there will be a vacuum after cooling down. Then keepthe jars with cover down and observe them about a week. The cover hasdo be bent in. If its straight or bent out, cook the jam again tosterilize and try closing another time.
The basic method of simply evaporating water until reachingconsistency has the disadvantage that cooking a long times means aloss in taste and nutrition quality. So consider the followingsolutions:
Use a strong cooker, because the more energy you put into the jam,the quicker the water will evaporate (without increasing thetemparature really) the less taste you loose.
You can use jelly (agar agar, a natural substance) to thinken thejam. It adds some "elastic" consitency that may be liked or not.
Most fruits bring some quantity of a substance (pectin) thatcauses the thikening. It is connected to the sour part. So usinggreen fruits or adding lemmon or apple helps.
Some bacteria survive 100Celsius but not a pH lower than 4.5. So keep the jam sour enough then cooking for 2 minutes makes it infinally storable. Cooking at only 80C for 10minutes may be better, but not so easy.