Scientist explains long-running theory on why Coke from McDonald's taste better

Finally, we know why Coca-Cola from McDonald's somehow tastes better thanks to science.

It's no secret American's love a nice cold Coke, with recent data estimating approximately 39.3 billion litres of Coca-Cola products have been consumed in the US this year alone with the states leading the way as the largest consumer overall.

This may come as no surprise, since you might agree that there is surely no greater refreshing drink than a McDonald's Coke, and if you've pondered this before, well, you're not alone.

Fans say the stream from the fast food restaurant's dispensers just hits better - it's colder, fizzier and somehow more satisfying, even with the soggy cardboard straw.

Diners have been adamant for years that McDonald's has the secret sauce to making the drink taste better.

Now, science has revealed there's a reason why it tickles the taste buds so.

McDonald's coke just hits better (Jakub Porzycki/NurPhoto via Getty Images)

Huffington Post invited the experts, alongside engineers and current and former McDonald's staff and an expert on carbonation, Brown University professor Roberto Zenit, to solve the riddle.

The report states it comes down to the franchise prioritizing the beverage.

"Every step of the way, McDonald’s goes the extra mile to ensure the best Diet Coke experience.

"Fundamentally, it comes down to a superior solute (syrup) to solvent (water) mixture to yield the solution (har) that is Diet Coke," the report explains.

Zenit told the outlet that a 'premium solvent is key' to the code, found in McDonald's reliance on filtered, pre-chilled water.

He says this is because the 'behavior of bubbles in carbonated drinks is determined by a physicochemical principle known as Henry’s Law'.

"According to Henry’s Law, the solubility of a gas (in this case, CO2) is directly proportional to its partial pressure and inversely proportional to the temperature of the liquid solvent (the water). Therefore, the colder the water, the more easily the carbon dioxide dissolves in it and maintains its gaseous state," the report continues.

How we receive it also plays a huge part - and McDonald's does this differently too (Smith Collection/Gado/Getty Images)

Next, is the syrup which, unlike other eateries that receive the cola syrup in plastic bags, is delivered via stainless steel tanks.

The report says this keeps the drink 'fresher and better-tasting by shielding it from the elements (sunlight, air, oxygen, etc.).'

Not only that, but the pros said it's also to do with the quantity and quality of the syrup, with McD's actively using a higher syrup-to-carbonated water ratio than standard products to 'compensate for dilution due to melting ice.'

Last but not least actually comes down to how we guzzle the drink down - quite literally the straw.

McDonald's has even publicly revealed that its straws are wider than standard versions by around 0.02 inches, which apparently makes all the difference.

As to why its so satisfying, Zenit theorized in his paper, The fluid mechanics of bubbly drinks, that it tickles more than our taste buds and actually does something to our brains.

"A scientific answer has proven elusive. Carbonation, it turns out, triggers the same pain receptors in the deep brain that are activated by tasting spicy food," he said.

Yet 'curiously,' he continued, 'when carbonated water is fed to other animals, such as mice, dogs and horses, the animals refuse to drink it.'

Indeed, it's only us humans who seem to enjoy its 'mildly irritating effects.'