Perhaps the purple carrot is not a vegetable you have much experience with, or ever thought about. When asked which variety was sweeter, orange or purple, one seller at my old farmer's market's answer was swift and unequivocal: “Orange.” At least with the varieties he was growing, the more common colour was the tastier. But purple carrots, whose hue comes from their heavy load of anthocyanins, have other talents.

Anthocyanins are present in blueberries, black rice, and even some autumn leaves. They operate as antioxidants, neutralising damaging oxygen species, which has led them to be darlings of the super-food industry. But that rich hue is another benefit – anthocynanins from various plant sources, like purple carrots, are approved by the EU and the UK to be used as food colourants.

Depending on their origins and specific chemistry, anthocyanins can turn food red, blue, or purple. These natural colourings can be used in foods that you would never connect with carrots or other sources of the molecules. Scientists have experimented with purple-carrot-tinged yoghurt and yoghurt coloured with extracts of the Peruvian berry B. boliviana. Even purple corn cobs have been tapped. Researchers found that they turn milk an attractive, vivid hue.

Purple-coloured carrots can crop up in the most unlikely places - such as making yoghurt a berry-like colour (Credit: Alamy)

Another switcheroo is one you may have noticed: the tendency for some exotic fruit juices to be, on closer inspection of the ingredients label, mostly apple or grape juice. The Which? consumer rights group wrote in 2012 that Tesco's mango and passion fruit smoothie contained 47% apple juice, 23% mango puree and 4% passion fruit puree. These inexpensive juices make a handy, well-understood vehicle for more expensive flavours. 

These days, juice labels have shifted in their descriptions. EU law now holds that “the product name shall be composed of a list of the fruits used, in descending order of the volume of the fruit juices or purées included, as indicated in the list of ingredients.” Though drinks with lychee, passion fruit, mango, and other exotics may still have substantial volumes of apple juice, labels must be more upfront, using names like “Apple and Mango Juice” instead. (Passion fruit rinds, however, have been tested out as a way to get more fibre into yoghurts that can be marketed as probiotic. Sometimes the exotic can hide in the commonplace for the sake of a marketing claim.)

It can be more difficult than you might think to encapsulate a flavour in a universal way

Of course, substitutions and disguises can also be part of something more existentially interesting: a global attempt to pin an elusive, complex sensation down to an easily replicable substance. Orange juice, for instance, is dosed with a flavour pack containing substances that say “orange” to drinkers.

As Alissa Hamilton, author of the book Squeezed, said in an interview with The New Yorker: “Flavour and fragrance houses, the same ones that make high-end perfumes, break down orange essence and oils into their constituent chemicals and then reassemble the individual chemicals in configurations that resemble nothing found in nature. Ethyl butyrate is one of the chemicals found in high concentrations in the flavour packs added to orange juice sold in North American markets, because flavour engineers have discovered that it imparts a fragrance that Americans like, and associate with a freshly squeezed orange.” 

The orange in your orange juice is sometimes boosted with flavours that mimic the real thing (Credit: Alamy)

It can be more difficult than you might think to encapsulate a flavour in a universal way, however. Many years ago, the Jelly Belly confectionery company put together a recipe for a pumpkin pie jelly bean. The company specialises in producing surprisingly specific tastes – as executive vice chairman of the board Lisa Brasher told me some years ago, "When you say 'pickle,' do you mean sweet or dill? When you say 'potato chip,' do you mean regular or barbecue? Those are very important questions for us."

Pumpkin pie – an essential part of an American Thanksgiving meal, rich with memories – proved a little too specific for success, however. With each individual thinking of their family's own concoction, the bean was not as instantly evocative as necessary. It was taken off the market.

Still, in 2014, the company brought the bean back as a seasonal variety. This time, the company's marketing material carefully noted the idiosyncracy of – and the corresponding difficult of satisfying eaters' – expectations: “Every family has their own recipe, and the Jelly Belly family is no different.”

As you eat your high-fibre yoghurt, sip orange juice, or perhaps even someday drink purple milk, keep your eyes open for these everyday glimpses of the chameleons in your food. Love them or avoid them, it's hard not to be impressed by the ingenuity behind these stand-ins.