produce

Extending the shelf life of produce

July 10, 2025 By EarthWise Leave a Comment

More than 30% of the world’s food is lost after it has been harvested. That’s enough to feed more than a billion people. Much of that loss is fruits and vegetables that go bad before they can be eaten.

Refrigeration is the most common way to preserve foods, but the energy and infrastructure required is not always available, especially in less affluent regions of the world.

Researchers at MIT and Singapore-based collaborators have demonstrated that they can extend the shelf life of harvested plants by injecting them with melatonin using biodegradable microneedles.

Silk microneedles are tiny, nontoxic, and biodegradable and represent a means of delivering nutrients to plants without triggering a stress response.

Melatonin is a natural hormone that plants already use. Injecting it was shown to extend vegetables’ shelf life. The tests used pak choy, an important Asian crop that is very perishable. Untreated plants at room temperature yellowed within two or three days. In contrast, treated plants stayed green for five days. Overall, treated plants retained saleable value for 8 days. Refrigerated plants had their shelf life extended considerably as well. However, the most significant value of the technique is that it could enhance the shelf life of perishable produce like pak choy without needing access to refrigeration.

The dose of melatonin delivered to the plants is so low that it is fully metabolized by the crops, so it would not significantly increase the amount normally present in the food. People would not ingest more melatonin than usual. The researchers believe that their technique should work with all kinds of produce.

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A new technology for extending the shelf life of produce

Photo, posted May 6, 2010, courtesy of Jessica Spengler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Making hydrogen using bioengineering

February 28, 2025 By EarthWise Leave a Comment

Hydrogen has great potential for helping society to reach net-zero emissions. The problem is that the most economical and established production methods for hydrogen depend heavily on fossil fuels and result in roughly a dozen kilograms of carbon dioxide emissions for every kilogram of hydrogen produced.

The carbon-free way to produce hydrogen is by splitting water into its component elements. This process generally requires the use of catalysts and lots of energy.

Researchers at the University of Oxford are developing a synthetic biology approach to the production of so-called green hydrogen. The idea is to replace expensive, exotic metal-based catalysts with a highly-efficient, stable, and cost-effective catalyst based on genetically-engineered bacteria.

There are specific microorganisms that can naturally induce the chemical reaction that reduces protons to hydrogen by the use of hydrogenase enzymes. While these reactions do occur naturally, they are limited to low hydrogen yields.

The Oxford researchers genetically engineered the bacterium Shewanella oneidensis by inserting a light activated electron pump called Gloeobacter rhodopsin as well as adding nanoparticles of graphene oxide and ferric sulfate. All of this tinkering with the bacterium resulted in a ten-fold increase in hydrogen yield.

The researchers believe that their system, based entirely on biological methods rather than traditional chemical approaches, could be scaled up to produce ‘artificial leaves’ that, when exposed to sunlight, would immediately begin producing hydrogen. The Oxford work was published last summer in the Proceedings of the National Academy of Science.

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A green fuels breakthrough: bio-engineering bacteria to become ‘hydrogen nanoreactors’

Photo, posted July 27, 2016, courtesy of Blondinrikard Froberg via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Politics and plastic

December 19, 2024 By EarthWise Leave a Comment

The world currently produces nearly half a billion tons of plastic each year. This is more than twice the amount it produced 20 years ago. Half of all plastics ever manufactured have been made in the past 20 years. Plastic waste is everywhere. About eight million tons of plastic waste escapes into the ocean each year.

Environmental groups have urged nations to adopt a legally binding treaty to address the ever-growing problem of plastic pollution. The United Nations climate conference in South Korea last month took up the issue of reaching agreement on such a treaty. At what was supposed to be the final round of talks on the topic, delegates could not bridge wide differences on what such a treaty should contain.

The main bone of contention was whether the treaty should include limits on plastic production itself. Saudi Arabia, Russia, Kuwait, and other oil-producing countries opposed any curbs on plastic production. They also opposed the phase-out of harmful chemicals used in the production of plastic.

The Saudi delegation claimed that if the issue of plastic pollution is addressed, there should be no problem with producing plastics. They said the problem is pollution itself, not plastics. They proposed a focus on improving recycling and waste management.

Of course, preventing plastic pollution from occurring is an extremely challenging thing to do. Delegates from countries pushing for a wide-ranging treaty – led by Rwanda – were unwilling to accept a toothless theory lacking real constraints on the plastics industry.

As the conference ended, delegates said that they would reconvene in future months to try again to produce a treaty. No date or place has been announced.

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Nations Fail to Reach an Agreement on Plastic Pollution

Photo, posted February 4, 2023, courtesy of Ingrid Taylar via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Greenhouses and the environment

July 25, 2024 By EarthWise Leave a Comment

The use of greenhouses around the world has been growing dramatically. A new satellite mapping exercise estimated the total land area covered with permanent greenhouses at 3.2 million acres, which is an area the size of Connecticut. More than half of this is in China, where the growth of greenhouses has been driven by the rapid urbanization of the country and by a more prosperous population increasingly consuming produce like tomatoes, cucumbers, peppers, and eggplants.

The intensive agricultural methods employed within greenhouses can be harmful to local environments because of overtaxing water supplies and by polluting rivers and soils with nutrients, pesticides, and plastic waste. But the effects of vast areas of plastic coverings on local temperatures can be even more dramatic, and often beneficial.

There are so many plastic and glass roofs in many areas that they are reflecting sufficient amounts of solar radiation to cool local temperatures. Greenhouse roofs increase the albedo – the reflectivity – of the land surface typically by a tenth.

All these greenhouses are just the tip of the albedo iceberg. Many farms now temporarily cover crops with reflective plastic sheets. If these coverings are included in the satellite survey, the total reflective area would be about ten times greater – roughly the size of New York State.

A study in Almeria, on the Mediterranean coast of Spain, which grows about 3 million tons of fruit and vegetables annually, determined the cooling effects of greenhouses. Weather stations amid the greenhouses showed an average cooling of 1.3 degrees Fahrenheit compared with the surrounding area.

Greenhouses are an accidental and benign form of climate engineering. The cooling provided by greenhouses is similar to the effect of white roofs in urban areas.

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Could the Global Boom in Greenhouses Help Cool the Planet?

Photo, posted September 6, 2017, courtesy of Lance Cheung / USDA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Plastic food packaging

May 9, 2024 By EarthWise Leave a Comment

Reducing the use of plastic is an important environmental goal. Plastic is made from fossil fuels and plastic pollutes the land and the oceans. It is estimated that 40% of plastic waste comes from packaging. Plastic packaging is extremely common in the supermarket and there is a growing desire to reduce its use. But it isn’t that easy.

Plastic packaging works well to slow the decay of vegetables and fruit. Its use results in less produce being tossed into the garbage, where it creates almost 60% of landfill methane emissions. In fact, food is the most common material in landfills. The average American family of four spends $1,500 a year on food that ends up uneaten and nearly half of all household food waste is fruits and vegetables.

Products like bagged salads, berries in plastic clamshells, and plastic sealed potatoes and cucumbers are popular with shoppers because they stay fresh longer. They are popular with grocers because the items don’t have to be weighed. But all these things result in plastic waste. It is a tradeoff that is difficult to make between food quality and safety vs. the environmental harm caused by plastic.

There are a variety of alternatives to plastic packaging of food that are being explored. They range from biodegradable, organic coatings that can take the place of plastic films, to cardboard and paper produce packaging.

But practically, there is yet no affordable and biodegradable plastic alternative that keeps fruits and vegetables safe and fresh. Solving the food packaging problem is not easy.

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So Much Produce Comes in Plastic. Is There a Better Way?

Photo, posted July 1, 2007, courtesy of Brian via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The carbon footprint of urban agriculture

March 22, 2024 By EarthWise Leave a Comment

Urban agriculture – essentially farming within a city – has become increasingly popular worldwide. It is intended to make cities and urban food systems more sustainable. There are social and nutritional benefits to urban agriculture, but its carbon footprint has not been widely studied.

There are high-tech, energy-intensive forms of urban agriculture, such as vertical farms and rooftop greenhouses. But most urban farms are decidedly low-tech such as individual gardens managed by single farmers and community gardens managed by small groups of people.

A comprehensive international study led by the University of Michigan calculated the greenhouse gas emissions associated with the materials and activities of urban farms over their operating lives. The emissions, expressed in the quantity of carbon dioxide equivalents produced per serving of food, were then compared to those of foods raised by conventional agriculture.

On average, food produced through urban agriculture emitted six times higher amounts of CO₂per serving than conventionally grown produce.

The study went on to recommend best practices crucial to making low-tech urban agriculture more carbon-competitive with conventional agriculture. These include making use of infrastructure for more extended periods of time, making use of urban waste, and maximizing social and health benefits.

Urban agriculture offers a variety of social, nutritional, and place-based environmental benefits and has its place in future sustainable cities. It is important to implement it in ways that are most beneficial.

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Study finds that urban agriculture must be carefully planned to have climate benefits

Photo, posted July 27, 2016, courtesy of Sandra Cohen-Rose and Colin Rose via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Fossil-free fertilizer

November 9, 2023 By EarthWise Leave a Comment

Ammonia is a major industrial commodity. About 70% of it is used to make fertilizer, with the rest for a wide range of industrial applications. Ammonia is the starting point for all mineral nitrogen fertilizers.

Typically, ammonia is a byproduct of isolating hydrogen from natural gas, which releases large amounts of carbon dioxide. On a global scale, the climate impact of ammonia production is comparable to that of air travel. The world needs more ammonia but really cannot afford the emissions that come with its production.

There are also political implications of ammonia production. Because it relies so heavily on natural gas, ammonia supply is vulnerable to disruptions from events like the Russian invasion of Ukraine. Sanctions imposed after the invasion have hindered fertilizer exports, driving up costs, especially in places like Africa.

A small fertilizer plant near Nairobi, Kenya will be the first farm in the world to produce its own nitrogen fertilizer on site that is free of fossil fuels. The plant is being built by an American startup company Talus Renewables and will use solar power to strip hydrogen from water. The hydrogen will then bond with nitrogen from the air to form liquid ammonia. The plant will produce one ton of ammonia each day.

The typical bag of fertilizer in sub-Saharan Africa travels 6,000 miles to get there, which of course only adds to the environmental burden of using it as well as its cost. By building a small green ammonia plant like the one coming online in Kenya, it is possible to locally produce a critical raw material in a carbon-free manner.

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Farm in Kenya First to Produce Fossil-Free Fertilizer On Site

Photo courtesy of Talus Renewables via LinkedIn.

Earth Wise is a production of WAMC Northeast Public Radio

Europe’s Green Deal: Bad For The Planet? | Earth Wise

December 28, 2020 By EarthWise Leave a Comment

In 2019, the European Union announced the “Green Deal,” a comprehensive program aimed at making Europe the first climate-neutral continent, implementing environmentally friendly transport, increasing recycling, and expanding renewable energy.

The Green Deal involves significant changes to European agriculture. Over the next ten years, under the ambitious environmental program, at least a quarter of all agricultural areas will be farmed organically, the use of fertilizers and pesticides greatly reduced, 3 billion trees planted, 15,000 miles of rivers restored, and the population declines of pollinators reversed.

However, in a recent article published in Nature, scientists at the Karlsruhe Institute of Technology show that this Green Deal might actually be a bad deal for the planet.

The problem is that the EU is likely to basically be outsourcing environmental damage by its high imports of agricultural products.

According to the Karlsruhe study, the EU annually imports millions of tons of agricultural products, as much as 20% of its produce and much of its meat and dairy products. Quite often, these imports come from countries whose environmental laws are far less stringent than those in Europe.

The EU cannot impose environmental standards on other countries, but it can demand that goods entering the European market meet EU requirements. The study points out that Europe’s carbon footprint has to be evaluated on a global basis. If the EU is truly to become a climate-neutral continent, it must include foreign trade goals and requirements in its environmental programs. Otherwise, Europe will simply be outsourcing its environmental problems and will continue to cause damage to the planet.

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Green Deal: Good for a Climate-neutral Europe – Bad for the Planet

Photo, posted July 17, 2009, courtesy of Edmund Garman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Preserving Produce With Eggs | Earth Wise

July 17, 2020 By EarthWise Leave a Comment

Researchers at Brown University have developed an inexpensive coating to protect fruits and vegetables that is made from eggs that would otherwise be wasted. The micron-thick coating solves problems for the produce and its consumers as well as for the environment.

The coating relies on eggs that never reach the market. The U.S. produces more than 7 billion eggs a year. The supply chain rejects about 3% of them, typically because of shell damage, which means that more than 200 million eggs end up in landfills.

The coating is mostly made from egg, the rest consisting of nanoscale cellulose extracted from wood, a tiny amount of curcumin (the main active ingredient in turmeric that has antimicrobial properties), and a bit of glycerol for added elasticity. The coating is applied to produce by spraying or dipping. It shows a remarkable ability to resist rotting for an extended period comparable to standard coatings like wax, but without their shortcomings.

Along with being edible, the coating retards dehydration, provides antimicrobial protection, and is largely impermeable to both water vapor to prevent dehydration and to gas to prevent premature ripening. The coating is entirely natural, and it washes off with water. So, anyone sensitive to the coating, such as someone with an egg allergy, can easily eliminate it.

Lab tests of the coating studied its effects on strawberries, avocados, bananas and other fruits. All were seen to maintain their freshness far longer than uncoated produce.

The researchers are continuing to refine the coating. They are also considering other source materials. They chose egg proteins because there are so many wasted eggs, but it may be possible to make use of plant proteins instead to address the needs of vegan consumers.

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Egg-based coating preserves fresh produce

Photo, posted July 13, 2012, courtesy of Liz West via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Protecting Fresh Produce | Earth Wise

May 26, 2020 By EarthWise Leave a Comment

Fresh fruits and vegetables can sometimes become contaminated by microorganisms during their long journey from fields to restaurants and grocery stores. Contaminated produce can spoil other produce, which increases the number of fruits and vegetables in the supply chain that can cause illnesses.

In order to prevent this cross-contamination between produce, researchers from Texas A&M University have designed a coating that can be applied to food-contact surfaces, like buckets, rollers, and conveyor belts. The newly-created dual-function coating is both water-repellent and germicidal. In other words, it can both repel and kill. Without water, the researchers say bacteria can’t stick or multiply on surfaces, drastically reducing contamination.

To make this dual-function coating, the researchers chemically-attached a thin layer of silica to an aluminum sheet. They then added a mixture of silica and lysozyme, a naturally-occurring germicidal protein found in egg whites and tears. Together, the silica-aluminum and the silica-lysozyme formed microscopic bumps and crevices. According to the research team, this rough texture, albeit microscopic, is the key to the coating’s superhydrophobic properties.

The researchers tested the coating’s effectiveness at curbing the growth of two strains of disease-causing bacteria: Salmonella and Listeria. Upon review, the number of bacteria found on the dual-coating surfaces was 99.99% less than what was found on the uncoated surfaces.

Despite the success in preventing bacterial spread, the research team said more research needs to be done to see how well the coating works for mitigating viral cross-contamination. Since the coating would need to be reapplied after a certain amount of use, the researchers also plan to develop more permanent, dual-function coatings.

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New dual-action coating keeps bacteria from cross-contaminating fresh produce

Photo, posted April 14, 2012, courtesy of U.S. Department of Agriculture via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Urban Agriculture And Sustainability Goals

November 12, 2019 By EarthWise Leave a Comment

In 2016, the City Council of Phoenix, Arizona adopted eight Environmental Sustainability goals for 2050 that lay out the desired long term requirements in order to become a Sustainable Desert City. Recently, a group of researchers from Arizona State University assessed how urban agriculture can help Phoenix, a desert city of 1.6 million people, meet those sustainability goals.

Using public records and high-resolution satellite imagery, researchers analyzed the potential benefits of growing crops in three types of urban areas in Phoenix: vacant lots, rooftops, and building facades. The study, which was supported by the National Science Foundation and the USDA, estimated that there are 28 square miles (or 5.4% of city space) available for urban agriculture. The data-driven analysis found that 71% of the available areas for urban agriculture would come from existing buildings as opposed to vacant lots.

All this available space for urban agriculture in Phoenix could supply the city with nearly 183,000 tons of fresh produce annually, which would allow for the delivery of fresh fruits and vegetables to all of the city’s existing food deserts. In fact, the city’s own urban-agriculture output could meet 90% of the fresh produce demand that currently exists in Phoenix.

In addition to producing food, rooftop agriculture could also reduce the energy use in buildings by 3% per building per year, and displace more than 55,000 tons of CO2 annually. The use of vacant lots could increase the total Phoenix green space by 17%, and reduce the number of areas lacking green space by 60%.

This study demonstrates the many different ways that urban agriculture can benefit a city.

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Urban agriculture can push the sustainability

Photo, posted May 10, 2011, courtesy of Stephen Zank via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Packing With Banana Leaves

July 25, 2019 By EarthWise Leave a Comment

More and more places are instituting bans on single-use plastic bags. Places like California and Hawaii already have bans in place and New Jersey is considering such a ban. New York’s law will go into effect next March. Supermarkets will no longer provide plastic bags at the checkout line. But the laws have some exceptions, including the plastic bags used to hold produce and to pack up meats.

Banning or reducing single-use plastic bags is a growing trend in Asia as well including places like South Korea, Vietnam and Thailand.

One supermarket in Thailand came up with a novel approach to eco-friendly packaging: wrapping produce in banana leaves. The idea quickly became a viral hit on social media and drew the attention of supermarkets in Vietnam. Several big supermarket chains in that country also began experimenting with banana leaves as a packaging alternative.

Representatives of Vietnam’s Lotte Mart chain said that the banana leaf packaging was still in the testing phase, but they plan to replace plastic with leaves nationwide very soon. Aside from wrapping vegetables and fruits, the grocery chain intends to also use the leaves for fresh meat products.

Customers seem to be quite positive about the new packaging noting that it is actually quite attractive visually. The banana leaf packaging also makes people more aware of the need for protecting the environment.

While Vietnam is a relatively small country, it turns out that it ranks number four in the world for the largest amount of plastic waste dumped into the ocean. The country disposes of about 2,500 tons of plastic waste per day. So, efforts like the banana leaf packaging are not just symbolically important, they are genuinely a major environmental imperative.

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Supermarkets in Asia are Now Using Banana Leaves Instead of Plastic Packaging

Photo courtesy of Perfect Homes Chiangmai via Facebook.

Earth Wise is a production of WAMC Northeast Public Radio.

Supermarkets And Zero-Waste

May 6, 2019 By EarthWise Leave a Comment

There are about 38,000 supermarkets in the United States alone and they are responsible for vast quantities of waste in the form of single-use plastic bags, plastic containers that store food products, and food waste as well. Globally, over 80% of poll respondents feel strongly that companies should help improve the environment. Responding to this message, markets are starting to make changes.

In a number of places, there are now markets that are package-free. The Nada grocery store in Vancouver and Precycle in Brooklyn are examples of zero waste grocery stores. Websites like Litterless provide online help for customers trying to find packaging-free grocery stores.

Markets are not only changing their packaging, they are using artificial intelligence to develop more sustainable production processes and seeking other ways to reduce waste.

On average, Americans throw away over 300 plastic bags a year, but an increasing number of grocery retailers are making commitments to more sustainable, plastic-free options. It isn’t just small stores either. Grocery giant Kroger plans to eliminate plastic bags in its stores by 2025. When that happens, it means that 6 billion plastic bags will no longer be distributed. Big Y stores will fully transition to reusable bags by next year. More and more cities and states are banning or imposing fees on plastic bags.

An interesting statistic shows that the age group of Americans that is leading the adoption of reusable grocery bags is not millennials but in fact is people over 50. With multiple generations now indicating that they want shopping to be more sustainable, it is likely that supermarkets will strive to help make that happen.

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