Each bottle of Toast Ale has the equivalent of one slice of bread in it. While you can taste the wheat and caramel notes from the bread, you won't find croutons bobbing in your brew.
Instead, the makers use leftover bread to replace a third of the malted barley that would otherwise be used for brewing.
Toast Ale sources its bread from sandwich-making factories, which have no use for the end slices of a loaf.
"The reality is that the end slice -- the crust -- is never going to end up on your sandwich," says Rob Wilson, Chief Toaster at Toast Ale. "In the production line there is somebody at the start of the line taking the crusts off and putting them straight into the bin."
Toast Ale estimates that 44% of the bread baked in the United Kingdom goes to waste, with households alone throwing away 24 million slices each day.
"I would love to give you this romantic story of me on a pedal bike going form artisanal bakery to artisanal bakery getting this bread, but the reality is bread waste is happening at an industrial scale," says Wilson.
Ancient Babylonian recipe
Brewing beer from fermented bread is not a novel concept. Toast Ale's recipe derives from a 4,000-year-old practice from the ancient city of Babylon in Mesopotamia.
The Brussels Beer Project first revived this age-old recipe with a beer made from recycled bread called Babylone. Food waste activist Tristram Stuart set up Toast Ale in 2015 after tasting a Babylone beer in Brussels.
In two years Toast Ale has expanded from Hackney Brewery in London to breweries in Yorkshire, New York, Rio de Janeiro, Cape Town and Reykjavik.
It has made its recipe public to encourage others to brew beer from bread. All its profits go to a food waste charity founded by Stuart, called Feedback, that campaigns to end food waste at all levels of the supply chain.
Is beer the best way to tackle bread waste?
Surplus bread is often redistributed to food banks and charities to feed the homeless. If unfit for human consumption, it can be used as animal feed.
But Toast Ale only uses bread destined for landfill.
While bread can also be used for composting or anaerobic digestion as a source of renewable energy, Wilson explains that this method of disposal is costly for most bakeries and sandwich manufacturers.
"Creating power from food waste is bonkers if you think about it," adds Wilson. "There are many more efficient ways you could power your light bulb than baking a loaf of bread."
The best solution for bread that would otherwise be binned is "diverting it back into the human supply chain," he says.
"We want the entire industry to start tackling this problem ... and the day that there is no more bread to be brewed is the day we can shut up shop. That's mission complete."