This is a problem that has been sought since the time when humans were overfed. How can the food be preserved for a long time if it is large?
There are probably as many answers to this question as there are types of food. In ancient Rome, figs were soaked in sea salt water and dried in the sun, while in ancient China, lemons and malts were covered with wax.
In 15th century Japan, vegetables were coated with soybean milk to preserve them for longer. In 16th century Britain, lard was used for this purpose.
Rotting fruits and spoiling grains were a major concern for our ancestors. In today’s world, the nature of the problem may have changed as global greenhouse gas emissions from food waste are 10% higher than those emitted from the UK alone.
Bad meat is one of the main reasons for this. Throwing away a hundred grams of meat means that you have released about ten kilograms of carbon dioxide into the atmosphere. However, the largest portion of food wasted worldwide consists of vegetables and fruits, which averages half a billion tons annually.
So what is the best way to preserve fruits and vegetables?
Plastics and chemicals are used in most ways to prevent food waste. According to a study published in 2022, the environmental benefits of preserving cucumbers in plastic are five times greater than the negative effects of plastic.
On the other hand, chlorine, hydrogen, oxide and trisodium phosphate are also used to increase the age of fresh fruits and vegetables.
But now consumers are starting to avoid chemical methods and use of plastic.
One reason for this is that the use of chlorine can lead to the formation of cancer-causing compounds that can be left on vegetables and fruits or found in water.
As far as the question of plastic is concerned, many people don’t think it is good to use more plastic.
David McClements, a food scientist at the University of Massachusetts, says the search for ways to preserve food without chemicals has increased in recent years.
Although most of the new techniques are still in the experimental stages, a few methods have emerged that do not use chemicals.
One such technique is to preserve fruits and vegetables in a preservative that can be eaten.
In the 1930s, the practice of preserving fruits such as apples with beeswax began. It should be noted that the natural peel of an apple also preserves it, but it is often lost during the cleaning process after picking from the tree.
Today, a similar synthetic coating is applied to other fruits, including apples, malts, and lemons.
In this way moisture inside the fruit is prevented from escaping. However, there is a lot of room for improvement. Scientists are now experimenting with different natural ingredients, from chitosan derived from silk and shellfish to gelatin and soy protein.
All these ingredients can be used to preserve fruits and vegetables in the form of a thin layer that prevents the release of gas and water and preserves the aroma for a long time.
McClements says chitosan, which is derived from shellfish shells, is an important part of food security efforts. In a recent study, strawberries were coated with a layer of chitosan, which increased their lifespan by 60 percent.
Similarly, tomatoes can be preserved for thirty days with the help of chitosan layer.
Various companies around the world are also part of this research process. California-based Apple Sciences is working on an oil that can double the life of food. In the US, their products are being used on a limited scale, while in the UK the company has a partnership with Tesco to sell preserved lemons and malts.
Another company called Liquid Cell is using a polyvinyl alcohol coating on mangoes and avocados in the UK.
Nano treatment
Another new method being considered for food safety is nanoparticles, materials that consist of cells of very small size.
In this way, the material used for the coating can be made stronger, McClements says.
In one study, in which plain strawberries left open for a week spoiled, only ten percent of the same fruit protected with a layer of chitosan and nanosilver spoiled.
On the other hand, carrots preserved with silver nanoparticles survived for seventy days.
Nanoparticles can also be incorporated into normal plastic packaging to preserve fruits and vegetables. They can also be used in sensors that can alert vendors when food is no longer safe to eat.
Researchers at McMaster University in Canada have developed patches that can warn of food spoilage ahead of time.
However, questions also arise with such an invention. Zinc oxide nanoparticles have caused liver and kidney cancer in mice. Silver or silver nanoparticles also leave effects on human cells.
Gustav Nyström works at the Swiss Federal Laboratories for Materials Science and Technology.
They say that with every new technology there are risks, so we need to be careful.
He says that nanoparticles of silver and zinc can accumulate in human tissue. However, according to him, they can be better used in plastic packaging to reduce their negative effects.
Natural defenses
Viruses that kill bacteria could be a possible solution. An American company called Intralytics is developing a similar virus-based material that can be used to preserve food.
The viruses, called bacteriophages, attack the bacterial cell wall and kill them, like poking a needle into a balloon, says Gert Kaiser, managing director of a company called Microvs. But are they safe?
Sam Nigan is a food scientist at Cornell University. “Bacteriophage are everywhere,” he says. We are completely covered by them.
He believes that commercial bacteriophages that can be used to preserve food will be available in the coming years.
Plasma water, use of ozone, ultra sound. These and various other methods are also under consideration. A unique answer may also be a method of preserving food with the help of artificial light.
However, before all of these techniques become commonplace, we need proof that they are safe for humans as well as food.
McClements says the technique has to be used on millions of fruits and vegetables, and it’s important that it’s cheap to use.
However, until these innovative methods become common, we can find simple solutions, one of which is to not buy more fruits and vegetables than we need.