It started on a modest scale with so-called “waste bread” – repurposing unsold bread that might otherwise go to waste into a new, larger sourdough loaf.

Now there are savoury crackers made with leftover cheese ends, baguettes turned into croutons, and day-old croissants filled with fresh ingredients. It’s all part of a drive by a UK bakery chain to become a zero-waste business.

At least 25 new products and initiatives are promised over the coming year by Gail’s, as part of an entire Waste Not range of foods which aims to cut down on ingredients squandered throughout the company’s supply chain.

Globally, the UN estimates global food waste causes about $940bn (£770bn) a year in economic losses. It says a third of the world’s food is wasted while one in nine people remain malnourished, while food waste also accounts for 8% of global greenhouse gas emissions.

Surplus bread remains one of the biggest waste problems for food retailers, according to the UK government’s food waste adviser Wrap, particularly from freshly baked lines which have a short shelf life. It is also wasted in our homes: Britons throw away 24m slices a day.

The original “waste bread” is made from strong white flour, malt, and a decades-old sourdough “starter”, mixed with so-called “bread porridge” – a brownish, flecked mush of fresh breadcrumbs from leftover loaves blitzed into tiny pieces.

“We freshly bake all our products every day and obviously we don’t know how much we are going to sell,” said Gail’s co-founder Tom Molnar. “The waste sourdough bread has proved very popular with our customers, and as a result, we decided to review our entire range of products and ingredients to see how best to tackle waste. It seems a good example of the circular economy in action and reflects the philosophy of our business.”

The circular economy model – which aims to use closed-loop production to keep resources in play for as long as possible – is being increasingly used in a range of different sectors from food, packaging, plastics and fashion.

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Gail’s opened its first bakery in Hampstead in 2005 and today has 59 outlets in London, Brighton, Cambridge, Oxford and elsewhere in the south-east. Every night, its shops donate unused food to more than 40 local charities, but any leftover bread not sold or distributed in this way has, for the last eighteen months, been diverted into the waste bread.

The first dozen Waste Not products, launched this month, include two more repurposed sourdough loaves – one using cheese.

Facebook Twitter Pinterest Waste Not bread products. Photograph: Steve Lancefield/PR

The chain also makes and sells up to 6,500 croissants every day, and those that are not sold are now being refreshed as part of the new range. Its ham and gruyère croissant, for example, uses yesterday’s flaky croissants filled with rich béchamel sauce, honey-glazed ham and gruyère cheese, then re-baked. Other croissants are similarly refashioned into almond versions. In the run-up to Easter, day-old hot cross buns will be turned into a novel breakfast version of the traditional bacon sarnie.

Shard-like cheese crackers are made from leftover dough scattered with cheddar cuts from Gail’s cheese supplier Quicke’s. Even its butter – part of the new range – is made from the whey cream left over from the cheese-making process.

Facebook Twitter Pinterest Cheese rolls from Gail’s Waste Not range. Photograph: Steve Lancefield/PR

Gail’s is also teaming up with Suffolk-based brewer Brewshed to create its first ever beer brewed with leftover bread, something increasingly popular in the brewing industry. Toast Ale, for example, was launched in 2016 by Tristram Stuart, the founder of the food waste charity Feedback, who was inspired by a Belgian brewer who follows the same process. Toast Ale has just launched its first beer brewed with ‘wonky’ crumpets made by Warburtons: Toasted Crumpet is a 4.2% abv session IPA where some malted barley has been replaced by crumpets that would have otherwise been disposed of.

Meanwhile, Marks & Spencer is repurposing leftover baguettes from its in-store bakeries into packs of crostini – extending their shelf life by seven days – and is also trialling turning leftover baguettes and boules into frozen garlic bread, extending their shelf life by 30 days.

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