The firms making meals from the bin

It was a £28,000 meal for a Russian businessman and his guests in London's exclusive Belgravia district that proved the final straw for then-private chef Justin Horne.

The lavish dinner party - which included caviar, foie gras and truffles - resulted in eight boxes of food simply being chucked away at the end of the night, making Mr Horne determined to do something about it.

"The levels of waste in fine dining are quite astounding," he says.

Together with fellow co-founder Alice Gilsenan, he is now running a pop-up restaurant, Tiny Leaf, in a food market in south London.

The concept, spelled out on a banner above the counter in black and white, is "zero waste".

Their menu is based on what shops and wholesalers can't sell and which otherwise would end up in the bin.

Mis-shapen carrots, bananas with black spots, bruised apples, day-old bread and croissants are the core ingredients.

It is all "perfectly consumable but just not beautiful enough for their [supermarket] shelves", says Ms Gilsenan.

The pop-up is the pair's second venture, after they ran a restaurant on a short-term lease to prove the concept could work. They're now looking for a permanent site.

"We've established there is a business case for this," says Ms Gilsenan.

The duo are part of a growing community of chefs, farmers and other members of the food world trying to make something tasty out of the mountains of waste.

A staggering one third of food, external produced for human consumption is lost or wasted globally, equivalent to about 1.3 billion tonnes.

The waste costs the average household £470 a year, according to figures from the UK government and EU-backed environmental agency Wrap, external.

At Tiny Leaf the aim is to throw nothing away. Carrot peelings, for example, are dehydrated to turn into crisps and the peel from lemons used to flavour a cheesecake or make limoncello. Any waste beyond this, and Ms Gilsenan says it's minimal, is given to composters.

Between 70-80% of the pop-up's ingredients are donated by shops and wholesalers.

On the challenge of running a restaurant when you don't know what ingredients you're going to get, Ms Gilsenan laughs and says it's all part of the fun.

One week they got 200 coconuts that ended up being used in juices and curries. But she says the menu has "a basic spine" of curries, soups and salads into which different vegetables can be swapped in and out depending on what they get.

Currently the pop-up is getting 250-350 customers a week and Ms Gilsenan says reactions have been largely positive.

"We have had some people say 'that's waste' but actually it's not waste, it's our perceptions of waste that need to be shifted."

Fear of a negative reaction from customers initially drove Rubies in the Rubble founder Jenny Costa to keep quiet on the origins of her chutneys, made out of fruit and vegetables destined for the bin.

She wanted to show that perfectly good produce, which had marks or was too close to its use-by-date to be sold to supermarkets, was still perfectly fine to use and most importantly tasted good.

"But in 2011, food waste was such a hippy notion that people immediately thought of bin divers, shuffling through garbage for something," she says.

Five years on, Rubies in the Rubble has graduated from a market stall to a supplier of jams, relishes and chutneys to several retailers including Ocado, Waitrose and Fortnum & Mason. Next year she's launching a range of ketchups, including one based on bananas which she insists is delicious.

One of the firm's business customers is Virgin Trains. It collects the discarded apples from Virgin's catering service each week and uses them to make chutney that the train firm then buys back to put into sandwiches.

Initially Rubies in the Rubble used discarded produce from wholesale fruit and veg markets, but the growth of the firm means it now buys would-be waste products directly from farmers for a discounted price.

Most of the UK supermarkets have now relaxed previously stringent specifications on the appearance of fruit and veg, enabling them to take more of farmers' "wonky crops".

But there is still substantial waste. This is largely because supermarkets need a certain shelf life for products, but also due to things such as warmer-than-expected weather, which can create a glut of a particular item.

"The volume of vegetables we use is small but we are one practical solution to food waste. We make sure they [fruit and vegetables] do have a market. We pay for them and put them back into the supply chain and there's a demand for it," says Ms Costa.

Chris Wilson, co-founder of the Too Good To Go app, was driven by a similar desire to tackle the waste in the restaurant industry. The app, which first launched in Denmark, lets people buy food from restaurants at a discount - food that otherwise would have been thrown away.

Since its UK launch in June, the social enterprise has secured deals with around 200 restaurants in eight cities.

Customers are given a time to pick up their meals, normally just before the restaurant closes, or after lunch ends and take them away in eco-friendly packaging. Too Good to Go takes a flat fee per sale that it reinvests in the business.

Mr Wilson says now they've proved the concept works they're trying to get deals with bigger chains. He says any fears that the app could hit a restaurant's existing sales are unfounded, noting they target different customers, typically ones with more time and less money, often students.

His real hope is that the app triggers people to think about the scale of food waste and makes them more conscious when they shop themselves.

In the 20 weeks since launch the app has been downloaded 80,000 times, with 10,000 meals sold through it.

But Mr Wilson says this is "just scratching the surface".

"It highlights how much work there is to be done if two guys can do this in no time at all. The food system is a huge, huge mess.

"Everyone says we're crazy. But change happens only when we make it happen."