While we know that Macca’s is far from the healthiest or most ethical choice for your next meal, there’s no denying that what they do, they do it well. Particularly that post-mix Coca-Cola. Something about it just tastes different to a regular Coke and as it turns out, it’s not all in your head.

An entire subreddit dedicated to the subject has cracked the code, and food scientists, as well as the corporation themselves, have backed the theories. But if you think you’ll be breaking out your own version at a home bar, we’re sorry to disappoint. The Macca’s Coke is kept under strict lock and key.

The reason McDonald’s Coke tastes different is four-fold. The primary difference between a pub post-mix and those at the Golden Arches is the way the syrup is transported and stored. The second secret ingredient is the water used. Third is the ratio of syrup to water, and lastly – the straw. Let’s get scientific!

Food scientist Abbey Thiel has busted the case wide open in a New York Post article revealing that by keeping the post-mix syrup and the carbonated water added ice-cold, the flavour of the product is different, and superior. While many venues keep their post-mix bags at ‘room temperature’ the actual ambient temperature can reach much, much higher when placed beside fridges and other mechanics. This heating can negatively affect the flavour of the syrup, making for an inferior fizzy fix.

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The key to success for the fast-food giant is consistency, so globally you can expect a very similar product whether you order it in Melbourne or in Memphis. As such, similar processes happen with the water added to post-mix around the world. Macca’s water goes through its own filtration, removing certain impurities that you might ordinarily find in tap water that could affect the flavour and colour of the end product.

Not only that, many McDonald’s franchises transport and store their Coke syrup in stainless steel tanks rather than plastic bags (or bladders) that come in square cardboard boxes. The stainless steel is another factor in how the resulting product tastes (Coke in a glass bottle vs Coke in a can – you see where we’re going with this).

The next surprising factor is just what Macca’s factors in when preparing its Coca-Cola. The powers that be know that your drink will inevitably water down and lose its fizz if added to a cup of ice. So what do they do? They slightly increase the ratio of syrup to water so your drink is stronger, and the super-chilled water and syrup traps the CO2 for longer, giving you more bubbles for your buck.

Finally, and most deceptively simple is the straw. The almost comically large straws at McDonald’s allow more of your drink to flood across your taste buds at once than a conventional thin straw. Because more of your taste buds are being stimulated at once, you’re going to taste more at once, which sends signals to your brain that you’re experiencing something really great – particularly if it’s high in sugar and teamed with the physical sensation of bubbles popping in your mouth. Science!

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