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About "Ask A Scientist!"

On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.

Previous Week's Question Published: 29 September, 1999 Next Week's Question
Glucose sweetens fruits as it ripens
Question
Why does fruit ripen?

Question
When fruits ripen they undergo a series of changes that alter the way they look, feel, taste and smell. These changes are good because they make fruits more enjoyable to eat, they are softer and taste better. Unfortunately, the ripening process is difficult to stop and it lets fruits ripen too much and they spoil! Unripe fruits have a number of different acids and their sugars are bound in up a network or polymer that does not allow us to taste their sweetness. Starch is one type of network and it is composed of the simple sugar, glucose. Breaking down the starch and releasing the glucose makes fruits sweet. The acids in fruits are also changed and therefore the fruits are not tart. All of these reactions and more occur during ripening and contribute to the fruit becoming sweeter.

Fruit ripens by producing enzymes, or catalysts that breakdown the sugar polymers and also neutralize the acids. They know it is time to ripen because they produce an odorless colorless gas, ethylene, that triggers the production of enzymes. A number of years ago, scientists discovered this process and now use it to control the ripening of fruit by carefully controlling the storage atmosphere. So now we can enjoy fruit almost year round, rather than just around harvest. And because the ripening process can be controlled and halted, we can also enjoy fruit from around the world shipped by boats and trains to our neighborhood supermarket.

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