The sun’s out and it’s time to light the charcoal and flip the burgers as the British barbecue season gets fully under way. Yet the red liquid oozing satisfyingly from your grilled patty or steak is as likely to be beetroot juice as blood.

UK supermarkets are scrambling to be the first to stock the most sophisticated fake steak and faux meat products so far, the result of innovations to improve the taste and texture of vegetarian options that go well beyond the soya chunks and mince that have been available for years.

While vegan purists may balk at the idea of eating an authentic-looking “burger that bleeds”, there is growing demand from the UK’s estimated 22 million “flexitarians”, who primarily have a vegetarian diet and want to reduce their meat consumption – a demand that is being met by companies in the Netherlands and the United States.

On Monday Tesco will launch the UK’s first plant-based steak in its 400 stores, in a year-long deal with Vivera, a Dutch supplier. The veggie steaks look authentically pink in the middle after cooking and are part of a range of more than 40 different meat alternatives.

But the big prize for Tesco is the cult US brand Beyond Meat. The retailer is understood to be finalising a deal that could mean Beyond Burgers are stocked in its freezers by July in time for summer BBQs, soon to be followed by the brand’s sausages.

The Los Angeles-based company, founded by Ethan Brown and backed by Bill Gates and Twitter co-founder Biz Stone, offers a plant-based burger that goes brown on the outside and pink on the inside when cooked. It has plans to roll out the Beyond Burger range across 50 countries and six continents this summer. In the US, Beyond Burgers are stocked alongside meat products, which is central to Brown’s vision of expanding beyond the vegetarian and vegan market to flexitarians.

A Tesco spokesman said of the plans: “This is something we are looking at but cannot confirm at this point.” In the past year, demand from Tesco customers for frozen meat-free foods has rocketed by more than 70%, while sales of chilled vegetarian ready meals and meat substitutes are up 30%.

Sainsbury’s is understood to be launching similar products as early as next month. Iceland is also expanding its meat-free range after the success of its No Bull burgers – containing beetroot – which were launched in April. Neil Nugent, head chef at Iceland, said: “We tested different textures and recipes in order to create the perfect no-meat meaty burger. You’d really struggle to tell the difference, it grills just like a regular burger so is brilliant for BBQ season this summer.”

And, next month, Waitrose is planning to expand the range of faux meat products it stocks from Dutch supplier The Vegetarian Butcher, including burgers made from plant-based protein. The retailer is also proposing to set up dedicated vegan sections in its stores.

According to the Vegan Society, more than half of UK adults are now adopting vegan buying behaviour, while the number of vegans in the UK, who shun all animal products including dairy and eggs, has grown fourfold in the past 10 years to around 550,000.

The implications for the global food industry are enormous. The US beef industry has filed a petition to exclude non-animal products from the definition of meat, while in France a new law bans vegetarian companies from calling their products “sausages”, “mince” or “bacon”.

But not every vegan or vegetarian is impressed by the new products. Evie Calder, founder of the ethical brand Atlas & Ortus and a vegetarian and “occasional vegan”, called the new-style products “totally unnecessary. Most people who follow a vegan diet do so because of the ethics associated with it, so I’m surprised that there’s demand for a vegan burger that ‘oozes’ blood. I suggest that instead of investing money in products like these, supermarkets invest in a wider range of products that are naturally vegan. While there is a place for fake meat as a stepping stone to a vegetarian or vegan diet, this is perhaps a step too far.”

A spokeswoman for the Vegan Society said: “Anything that gives more choice for people to eat vegan food is a positive move. Whereas sausages can be made both from animals and from plants and it’s a type of food many of us are used to, many vegans appreciate that people may simply want to have vegan versions of foods they grew up eating.

“A number of vegans believe we should move away from the idea of imitating animal products and simply consume plant-based dishes. This is great in theory but, in reality, many people still want to indulge in fatty, satisfying foods. Having vegan alternatives to animal products gives vegans yet another argument as to why there really is no excuse not to be vegan. It comes down to individual preference of vegans as there is no animal use in either case.”