Naturally, a large number of fruits ripen as a result of ethylene, a hormone produced by the fruits. The ripening process accelerates as the concentration of ethylene increases, changing the color, firmness, flavor, and characteristic aromas of each fruit.
Ethylene is a very volatile substance generated by fruits as they ripen, which is why it is considered an aging hormone. Due to the effect of ripening, the starch in fruits is transformed into sugars (fructose and glucose), tannins are also reduced (characteristic compounds of the “green” fruit that give it a bitter taste), and the pH increases, decreasing acidity.
All these transformations cause fruits to taste more pleasant to our palate when the acidic and sweet flavors intermingle. On the other hand, the colors of fruits are more accentuated when they are ripe, which means that concentrations of carotenes (yellow, orange, red) and anthocyanins (red, purple, blue) have increased.
Classifying fruits by how they ripen
Not all fruits are harvested when they are ready to eat. Some fruits require several days to complete the ripening process post-harvest, while others must be harvested at their optimum ripeness; they won’t ripen once cut from the tree or plant if harvested “green”. In some cases, fruits have reached sufficient ripeness to be sold, however, they still have some green spots, decreasing likelihood of purchase.
From the point of view of how the fruits ripen, we can classify them into: climacteric and non-climacteric fruit.