Analysis: how citrus waste left over from juice production could be used to make edible coatings for protecting food
The average Irish household loses €700 a year due to food waste. This means we are throwing about €60 per month in the bin. Food waste is not only related to environmental problems, such as waste accumulation/discard, contamination, and emission of greenhouse gases, but also to a waste of money and negative impacts on industry and economy. On top of being a massive waste of resources (land, water, energy, materials). According to the Environmental Protection Agency (EPA), the food supply chain stages that generate the most waste are households (31%), manufacturing/processing (29%), and restaurants/food service (23%).
The citrus industry, one of the largest fruit industries globally, generates millions of tons of waste annually through its associated juice production. After extracting the juice, almost half of the citrus fruit weight turns into waste, mainly composed of peels, seeds, and pulp. So, what's to be done with all of this waste? Right now most citrus waste ends up in the environment or landfills, used for animal feed or composting.
Consumers across the world have become more inclined to make sustainable choices and minimise waste in their day-to-day lives. In Ireland, the Government has planned a target for reducing food waste by 50% by 2030. So what if you knew that this citrus residue could be turned into an edible coating capable of protecting our food? Would you throw it away? Probably not.
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From RTÉ News, government sets target of reducing food waste by 50% by 2030
What's an edible coating?
In simple terms, edible coatings refer to a type of protective layer that can be applied to food items. These coatings are safe for consumption and are designed to extend the shelf life of the food, maintain its quality, and potentially enhance its appearance. They are often made from natural ingredients and can help reduce spoilage and preserve freshness. This technology helps in minimising post-harvest and economic losses, reducing food waste, mitigating associated environmental issues, and ultimately contributing to an increased food supply. Since edible coatings are not made from petroleum-based materials, they align with the current national goal of reducing the use of traditional plastic packaging.
For a better understanding of this concept, we can make the following analogy: for example, we wear clothes to protect our body from cold weather or rain. Edible coatings are a kind of "clothes" protecting our food. If you think about strawberries, they only last for four to five days in our fridge - so, if we could protect them and increase this storage period to 10 days, would you throw in the bin as much as you're currently doing? No. You would waste less, save money, as well as time spent on household shopping.
How can an edible coating be made from citrus waste?
The answer is in the orange peels, which can be used as a source of pectin. Pectin is a polysaccharide applied as a thickener or stabiliser, and is generally used in jams, desserts, soups, and drinks. Other compounds as natural antioxidants are present in orange peels and are related to beneficial effects on our health, such as the prevention of cardiovascular diseases and cancer.
Read more: 6 ways to reduce food waste in your home
After preparing orange juice, all citrus waste (including peels, pulp, and seeds) can be dried and turned into a powder that would be used in edible coating solutions. By using water, citrus powder, and other natural ingredients, we can produce a viscous solution where strawberries, for instance, can be dipped into it. Then, the strawberries are removed from the solution and left to dry in a tray or a rack at room temperature.
After that, our edible coating is done, the strawberries will last longer and be protected from pathogenic microorganisms and water loss, which will improve the freshness of the fruit. The best part is we can eat them with the coating, because it's been from a natural substance. Researchers have been working to make this and other technologies for the recovery of food waste viable. What we can say is that there's great potential hidden behind orange peels and so many other food wastes - a real treasure.
Watch: how can you make an edible coating for strawberries to protect them?
Of course, there's a long way to go to upscale the production process of these coating materials. Reintegrating these food wastes into the food chain represents a challenge for industrial, governmental, and research sectors, as well as requiring a thorough analysis of safety aspects to ensure consumer's health and wellbeing. This includes toxicological aspects, compliance with regulations, and evaluation of risks to the environment and ecosystems, in addition to a life cycle assessment.
However, given the unprecedented volume of food waste experienced in recent years, their uncontrolled and incorrect disposal, and low-value recovering practices such as animal feed, the development of new technologies for adding value to our food waste has become an urgent issue for society and should be treated as a high priority goal. So, it may be that the strawberries you eat in the coming years will be covered with a coating made from citrus wastes. That means food protecting food for a safer and more sustainable future.
The views expressed here are those of the author and do not represent or reflect the views of RTÉ
