Did you know in the past raisins were used as decoration? Or that Pop Tarts were originally unglazed? Here we take a look at surprising, interesting and downright mind-blowing facts about your favourite snack foods. Get ready to find out what flavour Skittles really are, what Pringles are made of and the secret ingredient in Krispy Kremes.

While you may think you’ve been tasting the rainbow, the truth is red, purple, green, orange and yellow Skittles all taste exactly the same. Your senses have been playing tricks on you. Colour and smell are psychologically proven to influence your mind as much as taste, and they’re also cheaper for the people at Skittles to change.

Though the recipe for melt-in-your-mouth Original Glazed doughnuts is locked in a vault and top secret, food historians believe the recipe contains fluffed egg whites, mashed potatoes, sugar, shortening, skimmed milk and flour. It was bought by Krispy Kreme founder Vernon Rudolph from a New Orleans chef in the 1930s and the company says it hasn’t changed since.

Check out these other sought-after fast food recipes

You may have eaten them since you were a kid, but did you know the Haribo Goldbears’ flavours aren’t what they seem? It would be sensible to think green means apple, kiwi or lime, but they're strawberry flavoured and, somewhat counterintuitively, the white ones are pineapple.

Thought McDonald’s chicken nuggets were all blob shaped? You thought wrong. The tasty chicken bites come in four distinct shapes which have names: the boot, the ball, the bone and the bell. See how many you can spot next time you pick up a box.

Check out more fascinating fast food facts here

If you’ve ever wondered why your bag of Reese’s Pieces always contains more orange than brown or yellow candies, it’s intentional. The tasty treats are meant to come in bags that contain 50% orange, 25% brown and 25% yellow pieces. What’s even more surprising is they’re all peanut flavoured. None of them contain chocolate.

The box calls them “crisps”, not because they’re British – they were invented in the US – but because they aren’t made with real potatoes. Our favourite, stackable, salty snacks are made with “dehydrated processed potato” and, because of this, in 1975 the Food and Drug Administration forced Procter & Gamble to change their name.

The friendly-faced man with a moustache on Pringles’ box is instantly recognisable. His name is Julius Pringles and he has had a number of updates over the years, his first in the mid-1960s when the brand was just taking off. He was revamped again in the 1990s and given more impressive facial hair.

In fact, a lawsuit was even filed against the chain after a number of sandwiches measured up short in 2013. However, it was concluded natural variability in baking means it's inevitable subs will be slightly different sizes and the sandwich giant was given the greenlight to keep doing what it’s doing.

Their sweet frosting and multicoloured sprinkles is half the reason why we eat them. But when Strawberry, Blueberry, Apple Currant and Brown Sugar Cinnamon Pop Tarts first came out in 1964, they were originally unglazed. It wasn't until 1967, when Dutch-Apple, Concord Grape and Raspberry toaster pastries joined the line they were given their trademark topping.

When Donald Goerke, who worked for Campbell’s Franco-American brand, was challenged to create a pasta dish for children that could be eaten with a spoon, SpaghettiOs were born. Invented in 1965, early advertisements described them as “practically unspillable”.

The controversial McDonald’s menu item was invented in the 1960s to elevate sales on Fridays, which is when Roman Catholics abstain from meat. Still most popular when people are forced to avoid Big Macs due to religious reasons, Filet-O-Fish sales usually skyrocket in March because of Lent.

Have you ever noticed some Bugles packets say General Mills and others say Tom’s? Unlikely, because the crisps look and taste the same, and the Bugles branding is identical. The indistinguishable crisps have two manufacturers because General Mills used to own Tom’s, but now just licenses the name and formula to it.

When raisins were first discovered dried on vines in 2000 BC in Mediterranean Europe, they were used for decoration in homes, according to wall paintings from the time. Later, the dried fruit was also used as a prize at sporting events, to trade with and in medicine.

It’s hard to believe the iconic, neon green St. Patrick’s Day milkshake is 50 years old. Invented in 1970, the seasonal beverage has returned every March (except for a brief period in the 1990s) to restaurants in America and some stores in Canada and Ireland. It also only became mint flavoured in 1983.

Smothered in peanut butter or eaten plain, multipurpose Graham crackers are as everyday as it gets. But did you know they were purposely designed to be boring? They were invented by a 19th-century puritanical minister, Sylvester Graham, as he believed the plain, grain-based biscuits would make people more wholesome.

You might drink this lemon and lime-flavoured beverage when you want something refreshing. However, when it was invented in 1929 it was even more of a pick-me-up. The mood-boosting chemical lithium was included in the recipe, which is also a drug prescribed to people with depression, bipolar disorder and mania.

In the early-19th century, when Velveeta was first invented, it was made from broken Swiss cheese wheels. The Monroe Cheese Factory in New York noticed it was wasting a lot of valuable product, so it gave cheesemaker Emil Frey the task of rescuing it. He melted the cheese wheel scraps and added whey to make a processed cheese with a velvet consistency. It was bought by Kraft Foods in 1927.

Ever wondered why the plasticky slices are called “cheese product”? Though they’re good for making queso, macaroni cheese and melting onto burgers, they don’t contain any real cheese. The main ingredients in Velveeta Original Cheese slices are whey, milk, milk protein concentrate, starch, oil and preservatives.

In January 2003, when Starbucks asked customers to vote on their favourite idea for a seasonal latte, next to options such chocolate-caramel, cinnamon streusel and spiced orange, the pumpkin pie flavour fell flat. It’s only because a project manager called Peter Dukes saw potential in the Pumpkin Spice Latte that it was saved.

Believe it or not hazelnuts were only added to the Nutella recipe to make the cocoa go further during the Second World War. However, now the luxurious hazelnut chocolate spread is so popular around the world – it has its own cookbook and bars dedicated to it – it’s causing hazelnut shortages.

In fact, there are a whopping 97 hazelnuts per every 750g (26oz) jar of Nutella. That equates to two nuts per 15g (0.5oz) portion you spread on toast. Ferrero uses 25% of the world's production of them each year, which is more than any other company.

To make enough Cheetos seasoning for a year’s supply of these extra cheesy, puffy crisps, 10 million lbs (4,536 metric tonnes) of Cheddar needs to be made. That takes 11 million gallons (1.4bn fl oz) of milk from 5,000 cows, which averages out to 2,200 gallons (281,600 fl oz) of milk per cow.

It’s nearly impossible to only eat one serving of them because every aspect of them is designed to be moreish, from their salty, sweetness to the way the puffs melt in your mouth. The latter tricks your brain into thinking there are no calories in them so you keep wanting more.

If you’re eating a bag of Lay’s potatoes chips, you may be surprised to know you could be eating local. That’s because Lay’s sources the potatoes for its chips from 120 farms in 25 states including Florida, Texas, North Carolina, Wisconsin, North Dakota, Washington, Maine and California.

Around the world you can get some inventive Lay’s flavours. Snack lovers in India can get their hands on Magic Masala crisps flavoured with the famous spice blend. Meanwhile, those in Indonesia can choose between options such as salty-sounding Nori Seaweed and intriguing Salmon Teriyaki.

Check out more unusual crisp flavours from around the world

Something no one would have expected, the chocolatey filling between the wafers in the British version of this snack time classic isn't plain chocolate. It’s ground up Kit Kats. This was found out during a documentary made at the Nestlé factory in York, England. It’s unclear whether Hershey's follows the same process making the chocolate bar in the US.

See if you can guess these popular childhood snacks from their close-ups?

When Disneyland first opened in 1955 there was a Tex-Mex restaurant in Frontierland called Casa De Fritos owned by Frito-Lay. Though tortilla snacks weren’t previously part of the snack giant’s repertoire, due to their success in the restaurant it added them to its line. They were rolled out nationwide in 1966 and named Doritos meaning “little golden things” in Spanish.

America can’t get enough of the crunchy, bitter chocolate cookie and soft, sweet crème combination of Oreos. Some people like to dunk them in milk, while others like to half them and eat the centre first. But did you know there’s an exact science to the cookie-to-crème ratio of its original cookies? It’s 71:29 and we think it’s perfect.

Now take a look at these nostalgic childhood snacks

Good news for plant-based eaters, Oreos are vegan. They contain sugar, flour, oil, cocoa, high fructose corn syrup, leavening, corn starch, salt, soy lecithin, vanillin and chocolate, but no milk. They just have milk as a “cross contact”, meaning a milk-containing product may be produced with the same machine.

The chocolate and vanilla sandwich cookie, first produced in Manhattan in 1912, is almost identical in appearance to the Hydrox cookie which was invented in 1908. What’s more, the latter is still around. Try one for yourself and see if you can spot any differences.

Learn about America's oldest surviving food brands here