A variety of products claim to keep produce fresh longer by absorbing ethylene gas. Preventing food waste is important, but do these products really work?
I've been seeing ads for products that things that claim to absorb ethylene, which allows produce to last longer. Do these products work? Would baking soda or activated charcoal do the same thing?
We've all had the disheartening experience of having to throw away expensive fruits and vegetables because we didn't use them quickly enough. No one likes to waste money, of course. But there's even more at stake with food waste. We throw away a shocking percentage of the food we produce. That's especially tragic when you consider how many people around the world experience hunger on a daily basis.
Hunger and food insecurity are not just issues faced by developing nations. Here in the United States, the richest nation in the world, more than 10% of households struggle to put food on the table. And that number has increased by 66% since the beginning of the Covid-19 pandemic. Right now, 50 million people (including 17 million children) in the U.S. do not have enough to eat on a regular basis. No matter where you live, if you're fortunate enough (as I have been) to have weathered this year-long crisis without worrying about how you'll feed yourself and your family, perhaps you'll join me in donating to your local food bank or an organization like FeedingAmerica.org. If you or someone you know is experiencing hunger or food insecurity, you don't have to go it alone. If you are in the U.S., FeedingAmerica.org can help connect you with resources in your area.
Food waste is also a major player in climate change. Rotting food is responsible for almost 10% of greenhouse gas emissions globally. In fact, if food waste were a country, it would come in third after the United States and China in terms of impact on global warming. And fresh produce makes up about a third of all the food we throw away.
If food waste were a country, it would come in third after the United States and China in terms of impact on global warming.
All of which is to say: If a $10 product could keep us from throwing away so much food, it would be money well spent. And I'm happy to report that there is some solid science to support these products. But their usefulness may be a bit more targeted than the marketing sometimes suggests.
What does ethylene do?
Ethylene is a harmless gas that is released or "exhaled" by fruits and vegetables. In general, ethylene production increases as fruits ripen and ethylene, in turn, accelerates the ripening process.
When we put unripe fruit in a paper bag, the idea is to trap some of the ethylene the produce gives off to hasten the ripening process. This works especially well for apricots, bananas, mangoes, tomatoes, avocadoes, and melons. But once the fruit is ripe, continued exposure to ethylene can cause it to become overripe and start to rot.
Ethylene can also speed the decline of other types of produce. According to horticultural scientist Kathleen Brown of Penn State University, ethylene can cause carrots and parsnips to get bitter, broccoli and kale to turn yellow, cucumbers and summer squash to get soft, asparagus to turn tough, apples to get mealy, and lettuce to wilt. Herbs such as parsley and mint are also sensitive to ethylene gas.
Low temperatures reduce a plant's sensitivity to ethylene, so keeping produce refrigerated will help to preserve it. In addition, you can use something to absorb ethylene gas.
If your avocados get ripe before you need them, you can hold them for a few days by putting them in the fridge. I find it most effective to move them to the fridge when they're still a day short of fully ripe, as some ripening will continue in the fridge.
What is zeolite?
Zeolite is a complex of minerals, including aluminum and silica, that is highly absorbent. It is used as a drying agent to suck moisture out of the air. (This is the stuff that makes clumping cat litter work.) But it also absorbs ethylene gas. Zeolites are widely used by food growers, shippers, and retailers to extend the shelf life of fruits and vegetables by slowing down the ripening process.
Produce-saving products that you may have seen in the consumer marketplace, such as the green produce bags or the hollow ball that you place in the crisper drawer of your fridge, contain zeolite. They are effective at absorbing ethylene and can prevent certain types of spoilage. These bags are reusable, but they will eventually lose effectiveness. You can also buy a rechargeable zeolite-filled ball to place in your crisper drawer to absorb ethylene gas.
Do other things absorb ethylene?
Gary also asked whether baking soda or activated charcoal might be effective at absorbing ethylene. I can't find any data to suggest that baking soda would be useful. Activated charcoal can absorb ethylene, but not nearly as effectively as zeolite.
Interestingly, the rechargeable ball (Bluapple) contains both zeolite and charcoal, but the manufacturer only mentions charcoal in their marketing. Perhaps they think charcoal sounds more natural and therefore more appealing to consumers. In terms of absorbing ethylene, I suspect the zeolite is doing the heavy lifting here. The charcoal may also have some odor-absorbing properties.
Spoilage that produce bags won't prevent
Keeping your produce in special ethylene-absorbing bags may indeed extend its shelf-life. Keeping high-ethylene producers like apples and avocados quarantined from other produce can also help. But remember that ethylene is only one of the things that can shorten the life of your produce. An ethylene-absorbing bag won't prevent moldy berries or slimy lettuce, for example. The best way to keep fruits and vegetables from going bad is to eat them promptly!
Here's a handy printable chart of the best way to store different types of produce.