More than one-third of farmed fruit and vegetables never reaches supermarket shelves because it is misshapen or the wrong size, new research from the University of Edinburgh suggests.

More than 50 million metric tons (MT) of fruit and vegetables grown across Europe are discarded each year, largely because they do not meet supermarkets and consumers’ standards of how they should look, the study showed.

The climate change impact of growing the wasted food – some of which may be ploughed back into fields, used in animal feed or otherwise reused – is equivalent to the carbon emissions of almost 400,000 cars.

Researchers examined details of food loss and waste within the European Economic Area. They studied how much food is discarded each year before it reaches the point of being sold.

They found that strict government regulations, supermarkets’ high standards and consumers’ expectations of how fruit and vegetables should look in combination led to the loss of more than one-third of produce before the point of sale.

Farmers who are contracted to supermarkets typically grow more food than they are obliged to supply, to allow for a proportion that will not be deemed fit to sell.

Scientists suggest that greater awareness among consumers, and a movement towards shopping sustainably, could encourage the sale of more ugly vegetables.

They also suggest a greater use of misshapen produce, for example in chopped, processed or picked goods, or for sale at a discount to charities.

Stephen Porter, of the University of Edinburgh's School of GeoSciences, said: "Encouraging people to be less picky about how their fruit and vegetables look could go a long way to cutting waste, reducing the impact of food production on the climate, and easing the food supply chain."

His colleague, professor  David Reay said: The scale of food that is wasted when it is perfectly safe to eat is shocking at a time when one-tenth of the world’s population is perpetually underfed."