The Science of Making Fruits and Veggies Last Longer - Jenny Du (Transcript)

Read the full transcript of engineer and chemist Jenny Du’s talk titled “The Science of Making Fruits and Veggies Last Longer”, recorded at TED2025 on April 10, 2025.

Listen to the audio version here:

The Ticking Time Bomb of Fresh Produce

JENNY DU: When you pick a piece of fruit off a tree, it’s like a ticking time bomb. It’s literally this living and breathing thing that’s slowly cannibalizing its own stores of energy and nutrients, just trying to stay alive until it ultimately gets eaten by microbes or some other animal like us. Have you ever wondered why that is and what could be done about it?

My journey in trying to figure that out started in the spring of 2013. I’m finishing up my post-doctoral research in chemistry at the University of Santa Barbara, California. All that really means is I’m a huge nerd and I’ve been in school for way too long. I’m trying to figure out how to put all that training to meaningful use.

The Staggering Reality of Food Waste

Two of my lab mates, James Rogers and Louis Perez, invite me to dinner, but it turns out to be a pitch, disguised as dinner, and they opened by totally flooring me with some staggering stats. A third of the food that we produce worldwide is lost or wasted before it ever has a chance to be eaten. For fresh fruits and vegetables, that number is a half. And waste is a problem at every single step of the supply chain. On the farm, trying to get it to market, in stores, restaurants, and in our homes.

And it’s not just a waste of the food. It’s a waste of the land, water, fertilizers, labor, energy, fuel, packaging, and money out of farmers and our pockets. If global food waste was a country, it would be the third highest emitter of greenhouse gases after China and the U.S.

The Limitations of Current Preservation Methods

For decades all around the world, we’ve relied heavily on a surprisingly small number of ways to help fruits and vegetables last longer after harvest. These have gotten us a really long way, but they also have their challenges. Refrigeration is a massive energy suck, a significant source of emissions, and it’s expensive. It’s unfortunately why a lot of places around the world don’t have access to refrigeration.

Designer pesticides aren’t great for our long-term health or the environment. Waxes, some can be plant-based, but a lot of them are also animal-derived or petroleum-derived. And they help make produce look better, but not really meaningfully extend their life and quality. And packaging, that’s just adding to our problems with single-use plastics and microplastics.

And then all of this leads to a pretty narrow set of fruits and vegetables that are available in stores today, relative to the amazing diversity of what’s really out there. And so, it’s really like the categories that can survive storage and transportation that are commonly available. And those aren’t always the ones that taste best or have the highest density of nutrients.

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Learning from Nature: How Plants Protect Themselves

So my friends wanted to approach this differently. And we led first with some questions. How do plants protect themselves? Well, with a peel. Plants, just like us, have a skin or peel, technically called the plant cuticle, and that helps to protect them from moisture loss, oxidation, and infection.

And what are those peels made of? Fatty acids, glycerides, that’s what’s the important part. And these are ingredients found universally in all plants, in the peel, pulp, and seeds, including in plants that we already eat. Different fruits have different shelf lives because of the thickness and arrangement of these materials in those peels.

So the idea then is, can we take these harmless, edible, plant-based ingredients, apply them in a thin layer on the surface of fresh fruits and vegetables to help reinforce the existing natural peel? And if you do that, can you help to retain peak flavor, texture, and nutrients for longer without reliance on refrigeration, pesticides, waxes, or plastics?

From Garage Experiment to Breakthrough

And so that’s what James Liu and I, that’s why we founded Appeal Sciences and ultimately headed to James’ garage to try and figure out. We started first by partnering with a small local grower. And we tested the idea on this category you may not have heard of called finger limes. They’re literally finger-shaped, and when you cut them open, the pulp is in the shape of beads like caviar.

They are delicious and they’re super-fragrant, but once they’re picked, that grower had maybe about seven days before their organic limes would start to dry out and the skin would start to change color, and that was even with refrigeration. So we took a test batch of material that we made using leftover tomato peels, since those are rich in these fatty acids and glycerides. We dipped those limes in a bowl of these ingredients and water and set them aside to dry, and then we waited. And we saw that we could add an extra week of freshness to these limes.

And when we saw that for the first time, we were like, “Shut the front door! Oh my God, this might actually work!” So we then went and wanted to apply this little bit of extra peel to all other kinds of fruits and vegetables. Bananas, avocados, limes, green beans, tomatoes, bell peppers, cucumbers, berries, like, you name it.

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What we saw amazed and, quite frankly, still amazes us. This concept works for dozens of categories. Things that need to ripen before you eat them, things that don’t, things that have edible peels, non-edible peels. We even saw that with protected blueberries, we could retain vitamin C levels at higher levels for longer than unprotected blueberries. And tomatoes could be harvested later, not when they were green and tasteless, but when they were red and actually ripe, and they’d still have enough time to get into your homes.

And we love that it really takes so little material.

The little bit of extra peel we add to an average avocado, for example, that’s equivalent in weight to a tenth of a small raisin. And even though these materials are, of course, they’re edible, you can wash them off by just rubbing under running water. We also, the more that we learned about the fresh produce supply chain today, we realized we could integrate into how these are processed in these packing houses before they’re sent to grocery stores. So, thinking about replacing a standard waxing step, for example.

Scaling Up and Making Impact

We’ve made good progress since those early days in the garage. And established a supply chain for reliably, responsibly sourced high purity ingredients. We’ve demonstrated safety and effectiveness to regulators in the U.S., the European Union, and more than 40 additional countries around the world. And while we’re still relatively small and early in our journey, we have a presence in about 10 markets worldwide.

What I’m most proud of, though, is why we got into all this in the first place. And that is that since 2021, when we started measuring, we’ve prevented 166 million pieces of produce from going to waste. In doing that, that’s avoided the emissions of more than 29,000 metric tons of greenhouse gas emissions, which is equivalent to planting 485,000 trees, and saved almost 7 billion liters of water, or enough to fill 2,800 Olympic-sized swimming pools.

What we’re also excited about is the opportunity to add a little extra peel to help small growers get their unique varieties of fruits and vegetables to market with more confidence. This is especially important in places that don’t have widespread or reliable access to refrigeration, like with these regional mango varieties. This could mean that a greater diversity of fruits and vegetables could be more available to more people.

Industry Resistance and the Path Forward

The work, though, is far from done. We’ve unfortunately encountered food and agriculture companies that have a really hard time seeing past the food waste status quo. Shrink, as it’s called in the industry, it’s just accepted as a normal part of doing business. And disappointingly, we’ve had some folks, producers, packers and retailers, tell us, “Well, the waste bin is kind of my best friend. The more that people throw away, the more they have to come back and buy again.”

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So let’s just say that’s not what we expected when we first approached them to talk about extending the life and quality of fresh products. But we can’t change this thinking alone, and we’re not a silver bullet to end food waste ourselves, but thankfully there are lots of start-ups, scale-ups, organizations and individuals all around the world working to transform this post-harvest space. And we’re optimistic that our one small innovation, using common ingredients inspired by the ancient wisdom of plants, is playing its part in having an impact, reinventing the food system and helping to create abundance for all. Thanks so much.

Q&A with Jenny

Incredible. Thank you, Jenny. I feel like when I buy avocados and then I bring them home and then I blink and they are rotten, how long could you extend the shelf life of an avocado?

Yeah. In your experience, maybe you have this too, there’s like a day, a day and a half when they’re like perfect. Right. Like avocado toast, cuttable before you’re like, do I sacrifice them to guacamole? Right. So take that day and a half and extend it to four days. Like maybe you’re actually going to have a chance to use it before you throw it away. Well, I’ve been more than doubling.

Wow. And when you’re spraying things that don’t have a shell, does it have a taste or does it have a smell or anything?

No. They’re very neutral. So no taste, no smell.

You saw we used a little of it. It’s like a strange thing we do around the office, which is like eat the fruit, lick the surface. Like confirm that. But we’ve also done it with credible other institutions like universities doing these blind taste tests with strawberries and you can’t tell that there’s anything on them. So amazing. Jenny Du, everybody. Thank you so much, Jenny. Thank you.

The Science of Making Fruits and Veggies Last Longer – Jenny Du (Transcript)