The universities of Loughborough, York and Nottingham are working together to discover better ways to reuse food waste and create a more circular economy in food production.
We are focusing on exploring technologies that will go far beyond energy recovery and unlock the full value of what we call unavoidable food supply-chain wastes.
According to the latest figures from the Waste and Resources Action Programme, every year food manufacturers generate 1.7 million tonnes of food waste, 2.8 million tonnes of food by-products and 0.7 million tonnes of surplus food. This is bad for the environment and economy, not to mention the moral implications of wasting such large amounts of edible food when people are going hungry.
The various ways we currently deal with food waste are not all necessarily the best options for the environment. These include anaerobic digestion, which uses microbes to break down food waste and create methane gas, composting, thermal treatments, and spreading on the land to fertilise the soil.
Charities and supermarkets do their best to redistribute edible food waste to families in need, but it is a very small amount compared to what is thrown away. Companies are also trying to reduce the amount of food that is wasted in the first place by improving storage conditions or using additives to increase shelf life.
Food waste is often used to generate energy. The most popular way companies do this in the UK is with anaerobic digestion plants, but the recovered energy only represents a fraction of the potential value of food waste.
However, some companies are trialling a green and affordable way to extract high-value materials such as natural antioxidants from food waste using a pilot technology called supercritical CO2 extraction. This works by exposing CO2 to precise temperatures and pressures to make it behave as a supercritical fluid, which is able to travel through solids like a gas and dissolve materials like a liquid.
It is a low-energy process, doesn’t involve dangerous solvents, and allows most compounds to be extracted without damaging them. Fruit peels used in the fruit-juice industry contain large amounts of the natural antioxidant limonene. Thanks to supercritical CO2 extraction, the limonene could be removed from the peel and added as a natural sweetener to juice or dairy products.
The process means that the amount of waste can be reduced, while generating added value and perhaps, in the very near future, making products that re-enter the food supply chain.
This collaborative research funded by the Engineering and Physical Sciences Research Council is pursuing – in partnership with big UK food manufacturers – a range of methods to reuse food waste through a combination of mechanical, thermo-mechanical, chemical or biochemical processes.