Sustainable AND Sprayable? Scientists Create a Plastic-Free Wrap From Carrot Pomace

Once you've squeezed all of the oil from an olive or the juice from a grape, what do you have left? Just a pile of useless skins?

Pomace is the leftover solid material from pressing fruits like grapes, apples, and olives. Some pomace gets used to make spirits like grappa, though most of it will end up as animal feed or fertilizer. However, scientists in Switzerland may have found a new use for pomace as a replacement for plastic film used to wrap produce.

Scientists at the Swiss Federal Laboratories for Materials Science and Technology, or Empa, working with retailer Lidl Switzerland, have worked together since 2019 to develop a plastic-free and biodegradable produce wrap. The new material, made from locally-sourced pomace, is a sprayable and non-toxic coating that protects fruits and vegetables from contamination, retains moisture, and keeps produce fresh up to a week longer than unwrapped food.

Scientists at Empa explored the possibility of using a more cost-effective source for cellular nanofiber (CNF) than wood pulp. Cellular nanofibers are microscopic interconnected fibrils, resulting in a material with properties similar to plastic. Researchers were able to create a coating that kept bananas and cucumbers fresher for a week longer than the uncoated control fruits using locally-sourced and unsellable pressed carrots. The coating is biodegradable and easy to wash off. Additionally, the new material is non-toxic and thus edible as well.

The process starts with juicing the unsaleable carrots; then, the resulting fibers get washed, bleached, then finely ground and dispersed in a homogeneous mixture. A thin, barely visible solution layer then gets sprayed onto the fruit.

Some produce, such as citrus, can last for weeks in cold and arid environments, while others degrade quickly, like cucumbers. While plastic has, unquestionably, a negative effect on the environment, banning plastic wrap on fruits and vegetables remains controversial. Some opponents argue that the food wasted due to this ban has a more significant environmental impact. A recent study by Empa concluded that one wasted cucumber was the ecological equivalent of 93 plastic wraps.

A pomace-based food wrap that performs as well as plastic while being biodegradable and sourced from local agricultural waste bridges the gap between spoiled food and trash pollution.

Lidl plans to pilot the new coating this summer, and the goal is to have it in use across 150 outlets across Switzerland.