how fruits become sweet Now, let's get back to fruit. Fruits, such as mandarin oranges and melons, get sweeter and more delicious as they ripen. Why is that? Hmm. When I was shopping for strawberries and mandarin oranges at the supermarket earlier, there was a sign that said, "Sugar Content: 11­12%." I suppose if fruit gets sweeter as it ripens, that just means that the sugar content has increased, right? Biochemically speaking, we must be talking about a change in the saccharides. You got it. So...let's talk about saccharides! Take a look at the graphs below. Before they're ripe, citrus fruits, such as mandarin oranges, contain roughly an equal amount of glucose, fructose, and sucrose. But as they ripen, the relative amount of sucrose steadily increases. In a Japanese pear, all three types increase.