The Real Reason Your Apples Keep Going Bad—and How to Fix It

For me, the saying "one bad apple spoils the whole bunch" conjures images of 18th-century children and a puritanical schoolmarm tsk-tsking at their shenanigans. The metaphor suggests that one bad influence can be magnified if left unchecked within a community. But how true is this saying for actual fruit? As an amateur apple grower with four little backyard trees and a garage fridge jammed with at least 100 pounds of fruit, I found myself wondering if a single apple could truly spoil them all.

Eager to understand how a bruised or damaged apple could potentially spell the downfall of its neighbors, I decided to learn more about the science of fruit ripening, the technologies the apple industry uses to manage its annual harvest, and a few key handling choices you and I can both implement in our kitchens to enjoy great apples instead of average ones.

The Science of Ripening

Let's start with the plant hormone that stimulates fruit ripening: ethylene. 

Ethylene is a gas that climacteric fruits—those that continue to ripen after harvest—naturally produce to initiate ripening as they mature. Climacteric fruits include apples, bananas, pears, stone fruits, avocados, cantaloupe, kiwis, peppers, and tomatoes, among many others. Non-climacteric fruits, such as cherries, berries, pineapples, citrus fruits, grapes, pomegranates, and watermelon, only ripen up to the point of harvest. 

In apples, respiration is the process by which the fruit uses oxygen and releases carbon dioxide—a kind of internal “breathing"—and as that respiration speeds up, it triggers the production of ethylene.

"When you look at an apple and you see all those little tiny pinpricks—some are more white, some are more yellow—those are actually lenticels, tiny little organelles through which the apple continues to respirate and mature after it's been harvested. They're still kind of living things in a very fundamentally strange way,” explained Ben Wenk, a seventh-generation apple grower at Three Springs Fruit Farm in Adams County, Pennsylvania. 

As soon as a single apple releases ethylene, it signals others nearby to ripen, too. We harness this process when we put a ripe apple or banana in a paper bag with underripe avocados to fast-track a batch of guacamole. What's going on in there? Ethylene triggers a cascade of physiological changes in the fruit: Enzymes signal the softening of cell walls, starches begin converting to sugars, and the fruit often changes color—green to yellow in bananas, and red in most tomatoes. It becomes sweeter, softer, and more aromatic, a biological "come and get me" signal to animals to consume the fruit and spread its seeds. 

Even if you don't regularly think about the biochemical pathways of plants, most of this feels intuitive to people who cook—deep amber peaches with pink cheeks and a heady aroma signal their ripeness in mouthwatering ways. But apples can be confusing: They retain their firm texture, and their color is less linked to ripeness than to sun exposure and varietal—those Granny Smiths stay green—so it's harder to intuit when they're ripe and, even more so, when they've tipped into over-ripeness. 

Apple growers think of ripeness a little differently. "In the fruit industry, we talk about maturity,” not ripeness, says Wenk. "They're congruent in a lot of ways, but they're not the same thing." Go to a pick-your-own orchard and you can enjoy the experience of picking an apple straight from the tree and taking a juicy bite, but growers managing hundreds of acres of fruit must also consider storability when deciding when to harvest.

Managing Ethylene's Chain Reaction

The thing about ethylene production and ripening is that it's a downhill roller coaster: It doesn't stop once the apples reach the perfect balance of sweet and crisp. There's a whole branch of agricultural science and industry—post-harvest preservation—devoted to managing ripening while preserving the most delicious qualities of an apple.

Ashley Thompson, PhD, an associate professor of horticulture and extension horticulturalist at Oregon State University, explains that apple growers can use specific agrochemicals to hasten or suppress ethylene production and manipulate harvest timing by slowing down ripening. 

After apples are harvested, growers bring the fruit to cold storage facilities, often sophisticated warehouses with controlled atmosphere (CA) technology. The apples are kept super-chilled at temperatures just above freezing, with reduced oxygen levels to slow respiration, essentially placing the fruit in a state of hibernation until it's ready to head to the grocery store.

Some specialized facilities, especially distribution warehouses that handle multiple types of produce, even use ethylene scrubbers: machines that filter the air for ethylene gas, mold spores, and bacteria. Another tool is 1-MCP, a synthetic compound with a chemical structure similar to ethylene. It's released as a gas into sealed fruit storage rooms, where it slows ripening and helps apples last longer. 

These storage facilities are the reason why apples are abundant in grocery stores year-round. Though peak apple season in the US generally runs from August to October, apples are available all year. Despite having been stored for many months—and, in some cases, a year or more—they often look and taste, to an undiscerning palate, nearly indistinguishable from a freshly-harvested one you might eat in October. According to Wenk, Washington has seen such an abundance of apple production in recent years that Honeycrisps harvested in 2023 were still being sold in the early months of 2025.

When Does Ripening Become Rot?

Whereas bananas have an obvious visual cue for overripeness—deep browning and freckling—apples are far more subtle. But they do cross over from ripe to overripe, and there are a few sensory cues to help evaluate where a piece of fruit falls on the spectrum. Overripe apples can look greasy and even feel oily to the touch. With prolonged exposure to ethylene, the fruit's naturally occurring surface wax shifts from a solid to a more liquid state. 

Another tell? Take a bite. As the fruit's internal starches convert to sugars, apples loses firmness, turning mealy and soft instead of crisp and crunchy. Granted, some types of apples are always on the softer side, so this is relative. 

If you notice these changes, Wenk says, an apple is likely approaching the end of its life. And it's here that the "one bad apple" theory really plays out. One damaged or overripe apple sends the equivalent of a biological distress call to others nearby, causing them all to deteriorate more quickly—a result of a hormonal process within the fruit itself.

Thompson explains that ethylene isn't just a growth hormone—it's also a stress-response hormone. And when an apple is stressed or damaged, it releases more ethylene, accelerating spoilage. Even a puncture from the stem of a neighboring apple can allow bacteria to enter. In addition to this increased ripening, she says, "the fruit becomes weaker and more likely to be invaded by pathogens," which is when ripening becomes rot. 

An undamaged overripe apple might lose its texture and become pulpy and unappetizing, but it's not inherently harmful; it's fine for making applesauce or apple butter. A bruised or punctured apple, on the other hand, becomes ground zero for microbial activity. Once the skin is breached, opportunistic fungi and bacteria can access the fruit's juicy interior—and from there, things go south fast.

Managing Apples at Home

This is why it's worth being selective when you're picking apples, whether at an orchard or the grocery store. Unless you plan to eat the apples immediately, it's best to pass over those with scrapes, bruises, or other damage—because they really do negatively affect one another.

Say you buy a perfect bag of apples, but trip, and a few of them become bruised or punctured. If you store all the apples together, the heightened ethylene from the damaged apples will hasten the ripening of the others. Refrigeration slows the effect, but even in the fridge, damaged fruit can still compromise otherwise good apples.

Your best chance to get the most out of all the apples is to separate the damaged from the undamaged ones immediately, stash the undamaged ones in the fridge, and eat the compromised apples as soon as possible. This strategy will give you the chance to enjoy each piece of fruit at its best.

While you're thinking about where you're going to put things in your fridge, remember that plenty of other produce have ethylene receptors, too—so other foods may react and continue to ripen if they're in the same place, Thompson adds.

Armed with this information, I'm better prepared to manage the apples stashed from this year's harvest. While my garage fridge is far less high-tech than a cold-storage facility, I have set the temperature to the lowest setting to mimic their super-chilled conditions—hopefully extending the shelf-life of my apples and preventing them from spoiling each other.

The Takeaway

• Sort early and often. As soon as you see an apple with a bruise or soft spot, remove it from the rest. One damaged fruit can fast-track the decline of the rest. 
• Keep apples super cool. Cold temperatures slow both ethylene production and microbial growth. As Serious Eats contributor Irvin Lin wrote in his story on the best way to store apples, the crisper drawer is your best friend. Use the high-humidity setting if you have one. 
• Separate climacteric fruits. Store apples apart from ethylene-sensitive produce, such as bananas, pears, avocados, and peaches, to prevent them from ripening or spoiling one another.
• Use the effect to your advantage. Need to ripen a hard pear or green banana quickly? Toss it in a paper bag with a ripe apple.