Last updated on October 23rd, 2023 at 08:15 pm
Of course, fruits and vegetables taste best when they are harvested fully ripe and can be enjoyed fresh. But it is often not so easy to find the right time to harvest. Sometimes early harvesting can also be useful to prevent diseases from the plant from spreading to the unripe fruit – for example, after a wet summer, from which outdoor tomatoes in particular suffered. It’s high time to find out how post-ripening actually works.
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Post-ripening: a little magic trick of nature
Even if you’ve never dealt with the subject before, you may have noticed that some types of fruit in the supermarket are offered almost rock-hard. Then you start to wonder: Do they taste good yet? Will they become even softer? On the other hand, sun-ripened, fragrant oranges lie next to peaches that still seem very unripe. One might think that they are picked early and ripen on their long journey to us. But oranges are one of those fruits that – once picked – cannot ripen at all.
Some fruits and vegetables have the ability to continue ripening separately from the plant by producing the ripening gas ethylene themselves. Other varieties, on the other hand, can only be supplied with this substance by the parent plant – their ripening stops as soon as this connection has been severed.
Oranges must therefore be harvested fully ripe and aromatic. To prevent them from spoiling during transport, they are kept fresh by appropriate refrigeration. Post-ripening varieties also keep much longer when refrigerated, as the ripening process is slowed down by low temperatures.
But what actually happens during this post-ripening process? Roughly speaking, the sugar content in the fruit increases. Carbohydrates, which are first in the form of starch, are converted into sugar. This is known as long-chain carbohydrates being broken down into shorter chains. Under the microscope, the carbohydrate molecules look like small chains. The small chains are then the sugar, which is why ripe bananas, for example, are sweet as sugar, whereas a few days earlier they still tasted mealy.
Which varieties are still ripening?
Post-ripening fruits and vegetables include:
- Apricots
- Nectarines
- Peaches
- Apples
- Pears
- Plums and damsons
- Kiwis and mini kiwis
- Figs
- Gooseberries
- Tomatoes
- Olives
You may have heard the term “picking ripeness”. It describes the ripening point at which the fruit can be picked, so that it can then be kept for some time longer. For example, if peaches were picked later, when they are already nice and juicy and soft, they could only be stored for a few days. With your own plants, of course, it’s possible to deliberately go past the date of picking ripeness if you’d rather harvest the fruit fully ripe and eat it quickly instead. Fully ripe fruits and vegetables contain the best flavor and the most vitamins and nutrients.
Fruits and vegetables that no longer ripen include:
- Cherries
- Grapes
- strawberries, raspberries, blackberries, blueberries, currants
- Citrus fruits (oranges, lemons, …)
- Peppers and chilies
- Zucchini
- Eggplants
- Cucumbers
- Cabbage and lettuce
- Carrots
Work your own magic: let fruits & vegetables ripen selectively.
Apples in particular are known to cause other fruits and vegetables to ripen faster in their vicinity. It emits a particularly large amount of ethylene, which can be absorbed by many other fruits and thus accelerates their ripening. For this reason, one hears again and again about the tip not to store apples and bananas together in the fruit basket. Bananas are particularly sensitive to the ripening gas and quickly turn brown and overripe (incidentally, they are then still perfect for banana ice cream or banana bread).
However, the apple’s ability to act as a ripening accelerator can also be used specifically to support still unripe fruits in their ripening process. This works for bananas, but also works particularly well for tomatoes.
Unfortunately, the idea of taking advantage of etching for varieties that are no longer ripening does not work. These varieties have no way of absorbing the gas in a suitable manner. For them, a lot of ethylene in the environment tends to cause them to wilt and shrivel faster.
To make peaches, apricots and the like even more aromatic, you can simply store them at room temperature, as they will slowly ripen on their own. If, on the other hand, they are already quite soft, although you would like to keep them fresh for a few days longer, you can slow down the natural ripening process in the refrigerator.
Tomatoes
Let’s take a closer look at tomatoes, as you often face a problem towards the end of their growing season: it’s getting cooler and wetter, but the plants are still hanging full of green tomatoes. The temperatures as well as the sunlight are no longer sufficient for these fruits to still ripen. Now the magic trick of post-ripening is particularly handy, as it can easily turn green into red in a short time. There are different methods of how this works best. You often read that tomatoes should be stored in the dark, but darkness is not at all necessary for the process. It’s best to just try what works best (and is easiest to implement) for you.
For example, you can lay out the green tomatoes on a baking tray, in boxes or crates. You should put them only in one layer, so that there are no pressure points. The room where you store the tomatoes in this way should be at least 18 degrees, but the fruit can withstand up to 30 degrees. Now you can watch how the tomatoes gradually turn red.
It is true that the riper the tomatoes were when they were picked, the lower temperatures they will tolerate when they ripen. Thus, almost red fruits can still be stored at 12 to 15 degrees and turn completely red.
Unripe, undamaged tomatoes can be wrapped in newspaper or wrapping paper. Loosely wrapped fruit can additionally be placed in a plastic bag to prevent the ripening gas from soaking in. It is very important to check the tomatoes every day and air them regularly. As soon as a tomato becomes moldy, others can also spoil very quickly. Therefore, be careful not to pack too many tomatoes in one bag, so that no bruises occur.
If you have enough space, you can also cut off the entire plant close to the ground and remove all the leaves. The remaining framework is hung. The fruits should ripen on the plant and thus develop a more intense flavor.
Pumpkin
Pumpkin is currently in season and can be categorized somewhere between “post-ripening” and “no longer post-ripening”. In order for it to continue to ripen after harvesting, it must have already reached its final size when picked. It is then usually ripe enough to be eaten, but develops a more intense aroma over 2 to 3 weeks and can then be stored better and have a longer shelf life. For post-ripening it needs about 15 to 20 degrees, it should not be warmer. It is stored dry, for example in a box or carton on sand, dry hay or straw and must be turned regularly. For storage, the pumpkins can then also be stacked, but should be unwashed and healthy and unharmed.