Apples are climacteric fruits, which means they continue ripening after being picked. The key to ripening them faster is ethylene, a natural gas that apples themselves produce and that triggers changes in color, texture, flavor, and aroma. If you have underripe apples, you can speed things up significantly with a few simple techniques.
Why Apples Ripen After Picking
Fruits fall into two categories: those that ripen only on the plant, and those that keep ripening after harvest. Apples belong to the second group. Once picked, they produce ethylene gas, which acts as a chemical signal that sets off a cascade of changes inside the fruit. Ethylene breaks down chlorophyll (turning green skin yellow), softens cell walls, converts starches into sugars, and generates the aromatic compounds that give a ripe apple its smell.
This process happens on its own at room temperature, but it can be slow, especially if the apples were picked early or have been refrigerated. The techniques below all work by increasing the ethylene concentration around the fruit or creating conditions where the apple responds to it more actively.
The Paper Bag Method
The simplest way to ripen apples faster is to place them in a paper bag at room temperature (around 20°C or 68°F). The bag traps the ethylene gas the apples naturally emit, raising the concentration around the fruit and accelerating ripening. A loosely closed paper bag works better than plastic because it still allows some airflow, which prevents excess moisture from building up and causing mold.
Check the apples daily. Most underripe apples will soften noticeably within two to five days using this method, depending on how green they were to start.
Adding a Ripening Partner
You can boost the ethylene inside the bag by adding a ripe banana or a tomato. Both are heavy ethylene producers. A single ripe banana in a paper bag with three or four apples creates a concentrated ethylene environment that can cut ripening time roughly in half compared to leaving the apples alone.
Any climacteric fruit works as a ripening partner, but bananas are the most practical choice because they produce large amounts of ethylene as their skin develops brown spots. A very ripe banana is more effective than a slightly yellow one. Swap the banana out if it starts to decay before your apples are ready.
Temperature Matters
Warmth drives the chemical reactions behind ripening. Apples ripen fastest at room temperature, roughly 18 to 24°C (65 to 75°F). Below about 10°C (50°F), ethylene production and the fruit’s response to it slow down dramatically, which is exactly why refrigeration keeps apples firm for weeks or months.
If your apples have been in the fridge, take them out and leave them on the counter. Cold storage doesn’t stop the ripening clock permanently; it just pauses it. Once the fruit warms up, ethylene production resumes and ripening picks up where it left off. Combining counter ripening with the paper bag method gives you the fastest results.
Avoid placing apples in direct sunlight or near a heat source. Temperatures above 30°C (86°F) can cause uneven softening and accelerate decay rather than producing the even, flavorful ripening you want.
How to Tell When They’re Ready
Color is the most reliable visual cue. Look at the parts of the skin that aren’t red or striped. This “ground color” shifts from green to yellow as chlorophyll breaks down during ripening. A green ground color means the apple still has a way to go. A creamy yellow tone signals ripeness for most varieties.
Other signs to look for:
- Firmness. A ripe apple gives slightly under gentle thumb pressure but doesn’t feel mushy. If it’s rock-hard with no give at all, it needs more time.
- Aroma. Sniff the bottom (blossom end) of the apple. Ripe apples produce fruity, sweet-smelling volatile compounds. An underripe apple has little to no scent.
- Seed color. If you cut one open, check the seeds. White or light-colored seeds indicate the apple is still immature. Dark brown seeds are a reliable sign of full ripeness.
- Taste. Starchy, tart flavor means the sugars haven’t fully developed yet. As the apple ripens, starches convert to sugars, and the taste becomes noticeably sweeter.
Slowing Ripening Once They’re Ready
Once your apples reach the ripeness you want, move them to the refrigerator. Cold temperatures between 1 and 4°C (34 to 39°F) slow ethylene production and respiration, which are the two processes that push a ripe apple toward becoming an overripe, mealy one. At fridge temperatures, ripe apples can hold their quality for several weeks.
Keep ripening apples away from other produce you want to stay fresh. The ethylene that apples emit will speed up ripening and spoilage in nearby fruits and vegetables, especially leafy greens, broccoli, and berries. If you’re storing apples in the fridge long-term, a sealed bag or crisper drawer helps contain the gas.
What If Your Apples Won’t Ripen?
If an apple was picked extremely early, before it reached a minimum stage of maturity on the tree, it may never develop good flavor or texture no matter what you do. Ethylene can only finish a process that the tree started. An apple harvested weeks too soon lacks the starch reserves needed to convert into sugar, and the result is a fruit that softens but stays bland or mealy.
Commercially sold apples are sometimes treated with an ethylene-blocking compound before cold storage to keep them in a suspended state of near-ripeness for months. These apples will still ripen once removed from storage, but they may take longer than you expect. The paper bag and banana technique is especially helpful here, since it floods the fruit with external ethylene to override the lingering effects of the blocker.