Page 144 - The Manga Guide to Biochemistry

4. Why Does Fruit Get Sweeter as It Ripens?

What types of sugar are in fruit?

Time for the fourth mystery: Why does
fruit get sweeter as it ripens?

Speaking of fruit, we just got some
fresh pears at my house...

Mmmm, they are ripe, sweet, and
delicious.

Actually, that’s true for many different
kinds of fruit. Mandarin oranges, grapes,
cantaloupes, and watermelons all get
tastier as they ripen.

You’ve got that right. When mandarin oranges are still a little greenish, they can be
way too acidic, but ripe ones are really sweet. And the melon that you brought over
earlier was in season and perfectly ripe!

Yep, but what does “ripe” mean, biochemically speaking? We know that ripe fruit is
sweeter, but why?

The reason is that three types of sugars are contained in large quantities in
fruits and berries: sucrose (table sugar), fructose (fruit sugar), and glucose (grape
sugar*).

Weird! I would have expected them to have only fruit sugar. We are talking about
fruit, after all...

* Despite the name, “grape” sugar is found in many fruits and berries, not just grapes.

130 Chapter 3