Ripe Fruit

I really like plums.  Several days ago I picked up several from the grocery, but when I tasted one, it was hard and too sour.  Like most fruit, plums are picked before they are ripe, so they will make it to the grocery without getting mashed.  What I needed was a way to get the plums to ripen quickly.  You can try this too.  You will need:

5 unripe plums,
 peaches, pears or tomatoes 
a ripe apple 
a paper bag

    First, taste one piece of the fruit.  If it is truly under ripe, it will be hard and not sweet.  Place two pieces of the fruit into the paper bag.  Put the apple into the bag too.  Fold the top of the bag and roll it to seal in the fruit. 
    Place the other two pieces of fruit in a dark place.  Be sure that they are not near the bag with the apple.  Wait until the next day.  Compare the fruit.  Taste one piece from the bag and one from outside the bag.  The fruit in the paper bag should be quite a bit riper than the fruit that you left out. 
     Wait another day and taste the last two pieces.  By this time, the fruit in the bag may be over ripe, while the other piece will be about the same as when you started. 
    What has happened?  Plants produce a gas called ethylene.  This gas causes the plant to produce chemicals called enzymes, which do several things. They cause the starch and acids in the fruit to change into sugar.  This makes the fruit more sweet and less sour.  They also weaken the cell walls, causing the fruit to soften. 
    Apples produce a lot of ethylene gas as they ripen.  By placing the unripe plums into the bag with the apple, you are adding extra ethylene, making them ripen faster.  As the fruit gets riper, it generates more and more ethylene.  This is where we get the saying that one bad apple spoils the whole barrel.  One overripe apple stored with the rest of your fruit can quickly cause it all to over ripen very quickly.  This experiment  was re-printed with permission from Robert Krampf

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