In this episode, we sit down with Angelos Deltsidis, assistant professor and postharvest Extension specialist at the University of Georgia Tifton campus, to explore the important role postharvest physiology has in preserving the quality and safety of our food supply and its broader implications for agriculture and global food security. From the moment fruits and vegetables are harvested to the time they reach our tables, a complex journey unfolds. Tune in to hear how Angelos is developing both innovative technologies and low-tech solutions to tackle postharvest challenges, from controlled atmosphere storage to using natural coatings on fruits and vegetables.
--- Produced by Jordan Powers, Emily Davenport and Emily Cabrera Edited by Jordan Powers Music and sound effects byMason McClintock, an Athens-based singer, songwriter and storyteller who creates innovative soul-pop music that transcends traditional genre boundaries. Hailing from small-town Southeast Georgia, Mason's influences range from the purest pop to the most powerful gospel. Mason is a former Georgia 4-H'er and University of Georgia graduate! Listen to his music on Spotify.
In this episode, we sit down with Angelos Deltsidis, assistant professor and postharvest Extension specialist at the University of Georgia Tifton campus, to explore the important role postharvest physiology has in preserving the quality and safety of our food supply and its broader implications for agriculture and global food security. From the moment fruits and vegetables are harvested to the time they reach our tables, a complex journey unfolds. Tune in to hear how Angelos is developing both innovative technologies and low-tech solutions to tackle postharvest challenges, from controlled atmosphere storage to using natural coatings on fruits and vegetables.
--- Produced by Jordan Powers, Emily Davenport and Emily Cabrera Edited by Jordan Powers Music and sound effects byMason McClintock, an Athens-based singer, songwriter and storyteller who creates innovative soul-pop music that transcends traditional genre boundaries. Hailing from small-town Southeast Georgia, Mason's influences range from the purest pop to the most powerful gospel. Mason is a former Georgia 4-H'er and University of Georgia graduate! Listen to his music on Spotify.
Welcome to Cultivating Curiosity, where we get down and dirty with the experts on all the ways science and agriculture touch our lives, from what we eat to how we live. I'm Emily Davenport.
Jordan Powers:
And I'm Jordan Powers. And we're from the University of Georgia's College of Agricultural and Environmental Sciences.
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Jordan Powers:
We are here with Angelos Deltsidis, assistant professor and postharvest Extension specialist. Angelos, thank you for having us down to Tifton today.
Angelos Deltsidis:
Good morning, Jordan and Emily. Thank you for driving down to Tifton. Always great to see you around.
Jordan Powers:
Before we dive into some of our topics today, we have a very hard hitting question for you. At mealtime, are you part of the clean plate club? Or are you a leftover lover?
Angelos Deltsidis:
That's a good question. I'm gonna say it depends. It depends on where I eat. For example, if I cook my own food, I just serve myself as much as I want. So I don't have to store or throw away anything. But if I'm eating at the restaurant, or the function, and I'm served more than I want to eat, I'll just store my food, I'll just have to go box and then store my food in the fridge overnight and have it for lunch the day after.
Jordan Powers:
Always good to have those leftovers. And we have a lot of episodes focused on food safety that we can link to as well, so people, if they're following that same path, they can make sure they're storing their leftovers safely to enjoy the next day.
Emily Davenport:
Yep, we'll link some of those in the show notes. Can you share your academic journey with us? How did you get started on your journey? And how did you end up here at CAES Tifton?
Angelos Deltsidis:
As you can tell by my last name, I'm Greek. I finished there my high school and then got into college at a city called Volos at the University of Thessaly. It's in the center of Greece. I did a four year degree over there. But at the second year of my studies there I was offered the opportunity to spend a semester at the US. I had the chance to go and work at the University of Florida where I got introduced into what we call postharvest physiology. I learned the great things it can do to help our farmers and our industries, reduce losses, improve profitability, and in general, help the world consume more of what we already produce, and not push for more production all the time. So fast forward. I finished my half a year program. I went back to Greece, where I graduated from my undergrad. And then at the conference, that very final year, I met the person I was working with, Dr. Brecht, and he offered me an assistantship for a PhD. I was very happy and very excited to have the opportunity, so I moved back to the US and I finished my PhD program at the University of Florida working under him, where we looked at the shelf life of tomatoes and other crops and how different storage conditions affect the quality. Towards the end of my work at UF, I applied for a job at the University of California, Davis and I got this job. So I moved to California when I worked in two entities. One of them was a postharvest technology center, which is an entity that houses a number of different specialists that work on post harvest. They offer a number of workshops and trainings for the industry to reduce losses after harvest and to improve quality of produce. At the same time I was working with at the University of California, Davis in the center I was mentioning. I was employed at the Horticulture Innovation Lab, also under the UC Davis, which was funded by USAID.
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Jordan Powers:
USAID is the United States Agency for International Development. We'll add a link in the show notes for you.
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Angelos Deltsidis:
The main goal of this lab was to work internationally do ag development projects in Asia and Africa, where we implemented low cost technologies to reduce losses and we also extended information that was produced in the US to the local populations. After that, in May 2019, I saw the announcement for the job opening at UGA Tifton. I applied for the job, I interviewed, and I got the position. Since 2019, I've been with the University of Georgia here in Tifton and building my program in postharvest physiology.
Jordan Powers:
And we are going to cover so many aspects of that program, from food loss to postharvest handling to the sustainability angle of everything behind your work. But before we really dive into it, can you tell us more about, what is postharvest physiology?
Angelos Deltsidis:
So as postharvest physiologists, we say that our work is to study the plant physiology of living plant tissues and organs after harvest. We look at what changes after you cut the fruit or the vegetable from the mother plant and how the quality changes after harvest. The quality will never improve after harvest. When you cut the product from the mother plant, it doesn't have any nutrients coming in. So the quality will only decline from that point on. So what we can do is we can just retain the quality to an acceptable level and we can just slow down senesence, which is a process of dying, we know that the product is going to die at some point, we just try to keep it alive as long as possible.
Emily Davenport:
Can you tell us what the percentage of loss specifically due to postharvest handling of produce is?
Angelos Deltsidis:
The number we usually use is about 30%.
Jordan Powers:
Wow.
Angelos Deltsidis:
But it's very hard to quantify losses after harvest, because we're talking about different countries, different industries, different setups of how people produce food, ship food, sell food, consume it, and whatnot. We use that number has been around for about 10, 15 years, and it's been about the same. But I've looked into the global losses and waste food after harvest by region, and it was interesting to find even contradictory studies. According to FAO, the developing world is having higher percentages of food loss and food waste as a total compared to the developed world.
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Jordan Powers:
FAO is the Food and Agriculture Organization, a specialized agency of the United Nations that leads international efforts to defeat hunger. FAO works in more than 130 countries worldwide.
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Angelos Deltsidis:
According to a fairly recent study, between 15 to 24% of the food produced in these regions of the world is not being consumed, it does not arrive to the retail level, on average the world from harvest all the way to retail, but not including retail, we're about 13%. But when we include retail and the losses at home, we probably get close to 30% that I mentioned earlier. The Western world, we have better infrastructure, we have better roads, better refrigeration systems, so our losses in the very early part of the value chain from harvest all the way to retail, they're much lower, we're about eight to 10%. So we're doing a good job early on. The problem in our case starts from the retail side onwards, because food in our region is available year-round, it's always fairly inexpensive, especially produce items compared to the incomes are not extremely expensive. So people are often purchasing more than they are expecting to use, just thinking that I'll just buy some more. And we've all made this mistake, and I'm guilty as charged, buying bananas at the store and then having to throw away a couple of bananas at the end of the week, because it just turned brown and they're too soft and too mushy. And who's gonna make banana bread? Just they're like, a dollar, so I'm gonna buy more.
Jordan Powers:
Yeah. It's, we've all been there.
Emily Davenport:
Yeah.
Jordan Powers:
Right?
Emily Davenport:
Yup.
Angelos Deltsidis:
Studies show that the losses in the final part of the value chain in the western world and in the rich Asian countries are significantly higher compared to the developing world. And this is because of what I mentioned earlier, we're more willing to throw away food that doesn't look good, or we're not willing to even buy it. So we have higher standards when it comes to what we are willing to buy. So grocery stores, farmers, and everybody involved in the value chain, have to throw away more food to keep us happy and keep us a good returning customer. And it's not always at the food that we are not consuming is dangerous for you or it's not fit for human consumption, it just doesn't look good. So because of how we've been trained, and how we learned, and we always buy with the eye, first, we just go to the store, and we try to pick the best-looking apple, avocado, you name it. So there's gonna be a number of produce items that will never make it to the table just because they're misshapen, or because they have a little nick and you name it. Training our people would be the easier way of probably to reducing classes, just telling people, hey, you can consume this apple that is a little bit misshapen, nothing's gonna go wrong. It doesn't look great, but it's just as healthy and as nutritious as the perfect round apple that you can buy.
Emily Davenport:
Mm-hm.
Angelos Deltsidis:
So you know, to make a long story short, we have a very high percentage of losses. And I've read a study some years ago that if you look at the total numbers between the developing world and developed world, the total losses do not differ much.
Emily Davenport:
Wow.
Angelos Deltsidis:
So even if we have the capacity of storing the product at the appropriate conditions and shipping it in refrigerated trucks and storing it in a refrigerated display, we end up losing about as much produce as the developing countries do just because, as I said, we can afford to throw away more, we are willing to pay more for better looking fruit and we are not consuming the misshapen ones. And also in that very particular to the United States or places where people have to drive away far away to get a product, you often buy more than you need because you can't plan ahead. You can't plan ahead for a week so you can buy fruit on Sunday and then by next Saturday or Sunday you're gonna go back to the store, maybe half of it will be gone or you bought too much and you don't know how to use it. So, you know, if you don't go to the store often, you end up overspending in produce items and by overspending you mean that you're buying products that you just throw to the dumpster.
Jordan Powers:
Wow, is this level of loss avoidable? And how is your research work toward reducing postharvest food waste going?
Angelos Deltsidis:
Let's be realistic, there's always going to be some percent of losses after harvest. There is no way that we can have a perfect system that you will save all the product, you will produce 100 pounds of apples and you will sell them all to the consumer. There's always going to be the produce that will end up having issues or fungal decaying, or they'll be crushed because of the weight and whatnot. But what we're doing here, and what my colleagues around the world are doing, is we're trying to reduce this loss as much as possible. We're employing many different technologies and techniques, from low cost and low tech ones all the way to more sophisticated. And we're trying to teach the stakeholders, our farmers, our grocery stores and everybody in between how to apply those and adhere to them to make sure that the product that we work so hard to produce in the field makes it to the store or as much product as possible from the field makes it to the store and then to our plates. And then, when we talk about the consumers, we're trying and we're doing extension work and educational events, to train them on how to appropriately shop and store their product and how to appropriately cook it in order to use as much of it as possible for their nutritional needs.
Jordan Powers:
There's so many layers to it. I'm also guilty as charged of, ooh, the giant thing of spinach is on sale. Oops, it's starting to wilt and we haven't used it all. Well, now we just chuck it in our freezer. And then we throw that spinach into smoothies and things like that with maybe the texture isn't quite as important. And even seeing it on the grocery store level I was shopping just the other day. And there was one small section in the produce department, it was very tiny, but a couple of shelves of kind of the misfit produce, right. And I scored a big ol' bag of yellow squash for 99 cents, like, this is great! So, you know, hopefully targeting maybe some of those more frugal minded shoppers as well that aren't as concerned about the aesthetics. It's really wonderful to see that starting in grocery stores and on the consumer end. But I'm excited to learn more and to see it hopefully develop in the coming years as well.
Emily Davenport:
Uh-huh.
Angelos Deltsidis:
Yeah, that's a great point. And it's been more and more common to see produce delivery services that we have around the country that send you a box weekly or every other week with produce that doesn't look good, but it's perfectly safe and healthy. And that's a very good first step to reduce food loss and food waste by training people and maybe by giving them a price cut on food that would otherwise go to the dumpster.
Jordan Powers:
A simple way to incentivize. To make a small difference.
Emily Davenport:
Definitely. We've already touched on a couple things. But can you give our audience some more high tech and low tech ways that you specifically are working to reduce postharvest loss?
Angelos Deltsidis:
As we say, jokingly, in the postharvest world, the top three ways of reducing post harvest losses are temperature, temperature, temperature.
Everyone:
[laughter]
Angelos Deltsidis:
So dimensioning that is important to know that the easiest way to reduce loss after harvest is by cooling the produce items to the target temperature and keeping it at that level throughout the shelf life of the product. If at any point you have a fluctuation either too high or too low of a temperature, you're going to end up having losses, or you're going to end up having disorders that ultimately will shorten the life of the product. That's the simplest way that we have. And the most efficient way, if you were to ask me what to do to keep your produce alive for a long time. After that, scientists, we're working with different technologies that are out there. Some are newer, some others are older. We have ways of reducing the oxygen and increasing the carbon dioxide in the storage chamber, what we call controlled or modified atmosphere. And by doing that, we slow down the respiration rate and the metabolic process in the plant. So we ended up extending the shelf life of the product significantly. But this is only applied to the product in addition to cold storage. You cannot forget about cooling your product and just store it at an ambient condition in high CO2 and low oxygen condition. There's other ways as well, there are coatings that one can apply after harvest that can create some sort of a shield around the product. And that's been used around the country in many commodities. Other ways of extending the shelf life of a product is by using technologies such as ozone or chlorination of the water where the product is washed to ensure that the pathogens that might be there are removed or are inactivated. And there's a lot of work being done at UGA by colleagues and, you know, we study the effects of those technologies on the quality of the product, but also we look at what they're able to do in reducing foodborne pathogens as well as pathogens that cause postharvest rots.
Jordan Powers:
So I've been blown away by the number of crops that can be grown in Georgia just with the climate here moving from the Midwest. So I know there are so many options when you say produce that you can be working with. What crops are you primarily working with in Georgia?
Angelos Deltsidis:
So I work with both fruits and vegetables. I work quite a bit with small fruit. I work with blueberries and blackberries that are growing in our region and their acreage is increasing year after year. I also work with peaches, as you know, we are the peach state, so it would be a shame not to work with peaches, right?
Emily Davenport:
Right, yeah.
Jordan Powers:
Exactly.
Angelos Deltsidis:
And then when it comes to the vegetable side, I work with vegetables grown down here in the southern part of the state. We have a good number of zucchini and cucumber farms around Tifton. So I've worked with them quite a bit. We also have the famous Vidalia region where we grow Vidalia onions. So I'm working in projects with the industry over in Vidalia. These are the main crops I'm working with. But then I also had some small projects with pecan nuts, you know, they're dry and they have a longer shelf life. But still, the quality is degrading after harvest, and there is work that can be done to extend the quality and maintain that crunchy and fresh flavor after harvest. So I've worked with all three, fruits, vegetables and nuts, but my main focus is fruits and vegetables.
Emily Davenport:
So we've touched a little bit on this question already. But I'd love to dive deeper into the difference between food waste and food loss.
Angelos Deltsidis:
These two terms are used many times interchangeably, or people confuse one for the other. By talking about food losses, we talk about the situation when food unavoidably becomes unfit for human consumption before people have a chance to eat it. This is most prevalent as I mentioned earlier in lower income countries when food is unintentionally damaged or destroyed by pests or mold or there's no refrigeration to keep the product in a good condition to be eaten. Don't think that we don't have food losses in the United States. As I mentioned, we are doing also a poor job often in the latter part of the value chain by discarding product that is perfectly fit to eat because we just want to sell only the best looking product out there. So when we talk about food waste, this is when we as consumers discard food that's still fit for human consumption either before or after it goes bad. This particular situation happens most often in high income countries such as the United States, and also at restaurants, hotels, as well as households. So we're all guilty at some point in our lives of throwing away perfectly healthy and good looking products, because we just are not in the mood of eating it, because we just had too much of it, because we just bought too much. And we can only eat so many bananas in a week.
Emily Davenport:
Yeah.
Angelos Deltsidis:
The banana story goes around in this discussion. The combination of the two, food loss and waste, is recognized to be a very serious threat to food security, the economy, and the environment, ultimately. We need to pay a big attention to how we manage our production and how we make sure that the losses across the value chain are kept at a low level.
Jordan Powers:
We've talked about, from farm to table, the food waste and food loss occurring throughout the agricultural production line. What type of numbers are we talking about behind these losses?
Angelos Deltsidis:
So According to FAO, approximately 1.3 billion metric tons of edible food is lost and wasted across the entire supply chain every year. Just to give you an idea of what this would be in dollar value, that's about 950 to a trillion US dollars annually around the world.
Jordan Powers:
Wow.
Emily Davenport:
Wow.
Angelos Deltsidis:
So if we were doing a better job in keeping
Jordan Powers:
When we're looking at this big picture, do these produce items that we produce already to an acceptable level for them to be consumed, we will alleviate the undernourishment for 1/8 of the world population. As I mentioned earlier, the amount of food loss and waste varies between countries and regions. It's influenced by the income levels, the urbanization, the economic growth and more factors. in less you view your work in the context of addressing food developed countries, we have the food loss and waste mainly in the early stages of postharvest and processing stages. Whereas in the more developed world, we have a big percentage of food loss and waste in the consumption stage, which is where we as consumers are the drivers of these losses. The amount of food waste in our industrialized world is approximately 220 million tonnes, which is almost equal to the total net production of subsaharan African countries. Just to give you an example of how much we waste, often insecurity around the world? willingly, just because we can afford it or just because we've learned to do that throughout our lives.
Angelos Deltsidis:
Definitely. We're not trying to solve each and every problem or each and every aspect of this issue. As I mentioned, it's a multifaceted issue. It happens throughout the value chain. So we are just putting effort in the areas that we can and we're working mainly in the earlier stages we don't work as much with the consumer level, but we work with stakeholders in all stages from harvest all the way to retail. And we're trying to implement appropriate practices to make sure that the product that we are producing and it's perfectly fine to be consumed makes it to the plates of our people in the country and around the world.
Jordan Powers:
We've talked a lot about the research going into fighting food insecurity, food waste, and food loss, but what can our listeners incorporate into their daily routines?
Angelos Deltsidis:
So I have a few bullet points that they can have in mind when they shop, when they make their plans for the week. They should plan ahead before they go to the store or before they buy online to make sure they buy only what they need. They should also serve smart by controlling the portions because it's not only good for our waistline, but it's also good for reducing the waste of the food that we cooked. As you both mentioned, we should love more our leftovers and just use it. There are ways of saving the leftovers safely so that we can eat them at a later point. And usually by refrigeration, you can use the product for a few days after they're cooked. without any issues. When it comes to products that have to be discarded, it's preferable to compost that product and not just throw it in the dumpster. Another thing that we all often struggle with is understanding date labels. Usually product that has been handled properly is still safe by the date that is being printed on the label. So don't throw that product a day or two early just thinking oh, it's probably bad. These are very conservative dates that are there. And usually the product is even safe afterwards. So long as it has been, of course, stored the appropriate conditions. When it comes to perishables like most of our produce items you want to buy and consume them as quickly as possible. Don't buy in bulk, trying to think that you're going to save money, because often you end up buying too much and then you end up throwing it away. As Jordan mentioned, if you buy too much, so happens that you have too much spinach, let's say in your fridge, just freeze it when it's about to go bad, don't throw it away. Or make something other just to make sure the product that you already paid for is still consumed. And then when it comes to people that order and they just get food from restaurants, just order wisely, don't buy too much. Don't think that by ordering more, you're gonna save yourself the hassle of going out twice, because usually you end up buying too much. And then the product will either go bad or you just gonna get sick of it and you want to throw it away because you can only eat so much of the same food day after day. So, you know, there's many ways that we can help this goal. And we can reduce food waste by just changing little things in our habits. And of course, we all make mistakes. But if we have these things in mind, we'll probably do a better job as a society in the goal of reducing losses after harvest.
Jordan Powers:
We can all play a role
Emily Davenport:
That's right.
Jordan Powers:
in reducing it. And for our listening audience, we see that Angeles has a wonderful little cheat sheet from the USDA with those tips on it. So we'll make sure to find that and link that in the show notes as well so that people can print it out and maybe have it right in their meal planner on their fridge at home.
Emily Davenport:
That's right.
Jordan Powers:
I'm gonna sneak in one final question. What excites you most about your work?
Angelos Deltsidis:
That's a great question. What I've been seeing and reading about is that the majority of research and the majority of funding in our world goes towards production. What can we do to produce more? What can we do to increase the yield? What can we do to make this plant just give us more fruit or vegetables? What we do is we're not pushing the plant or the environment to give us more product, which is, don't get me wrong, it's important, but we're trying to save what we already produced. So we're trying to give the people that worked very hard to produce fruits, vegetables, to give them a better return on their investment. And we're also trying to reduce the pressure towards our world or towards the earth of producing more and more fruits and vegetables by just saving what we already produced and making sure this product makes it to our tables.
Jordan Powers:
Very interesting side to agriculture that we don't hear about nearly often enough.
Emily Davenport:
Yep.
Jordan Powers:
Well, Angelos, we appreciate you so much. We appreciate the work you're doing. We appreciate you taking the time out of a busy day and inviting us down here to Tifton. It's always wonderful to come down. So thank you so much for your time.
Angelos Deltsidis:
Thank you so much, both.
Emily Davenport:
Thank you.
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Emily Davenport:
Thanks for listening to Cultivating Curiosity, a podcast produced by the UGA College of Agricultural and Environmental Sciences. A special thanks to Mason McClintock for our music and sound effects. Find more episodes wherever you get your podcasts.