The Big Mac special sauce is one of those closely-guarded secret recipes that has kept us guessing for decades. It's transported to restaurants in sealed canisters, and dispensed using a sauce gun designed to shield the sauce from prying eyes until it hits the Big Mac. While we can decode DNA and develop nanobots, we just can't pin down the secret ingredients of this gastronomic delight.
But if you've been tearing your hair out trying to recreate the taste, it's your lucky day, because McDonald's has made 200 limited edition bottles of the sauce. There's only one slight snag: the first one is up for sale on eBay in Australia and bidding has reached over $23,000 (£12,000).
Bidding is also only open to pre-approved bidders, which is designed to ensure that only serious bidders are allowed to take part in the auction. It should put a stop to headline-grabbing sums that eventually fail to materialise. There are eight days left on the item too, so we could easily see the price rise even higher.
The listing reads: "This bottle is #1 of only 200 being produced worldwide, and they won't be sold in restaurants. That makes it rarer than a spot on Bondi beach on New Years Day." It adds: "So slide the mustard, mayo and tomato sauce to the back of the fridge – because everything tastes better when it tastes like the Big Mac."
The auction profits will go to Ronald McDonald House Charities, so you are raising money for a good cause too. Unfortunately the seller will only post to Australia, so you'll need to take a trip, or ask a friend in Australia to buy it for you.
Those lucky Australians will also be able to buy 25ml tubs of the sauce from 920 McDonald's branches - for just 50 cents. However, with just 600 tubs available in each store, several have already hit eBay, with one reseller charging £4.33 for a tub.
Another chancer has put two of the tiny tubs up for sale with a picture of the larger bottle with an asking price of $71,000, and the statement that they won't be responsible for people who think they are buying the bottle.
The rest of the limited edition bottles have been sent to food writers and journalists, who are busy blogging and hash tagging #macitbetter
If you want to get your hands on some sauce in the UK, the chain has revealed that the sauce's ingredients are no secret – relish, mustard, onion, garlic and mayo – all you have to do is master the top secret balance of flavours, and you too can make everything taste like a Big Mac - for significantly less than £17,000.
A number of brands have built their name on a mysterious secret formula. Coca-Cola, for example, claims to keep it in a vault inside the company's headquarters in Atlanta. Company legend has it that although it was devised in 1886 the recipe was handed down by word of mouth, and only written down in 1919. At that point it was kept safely in the bank, until 2006, when it was moved to the purpose-built vault at headquarters. It claims that only two senior executives know the recipe at any given time, and that they are not allowed to travel on the same plane.
It's not alone in this approach, another big famous secret recipe is for KFC. The firm keeps it secret by having two containers of 'secret recipe' spice mix, so that the manufacturers only ever know half of the recipe. These are only combined in the branches themselves, when the chicken is dipped in one and then the other, before frying. It too has the 11 secret herbs and spices written on a piece of paper inside a state-of-the-art vault inside the company headquarters in Louisville Kentucky.
On a regular basis people claim to have discovered these secrets, but in reality they're not a vast amount of use to anyone. If you have the KFC recipe, you can recreate the mix, but without the cooking equipment, you could never recreate the taste.
Likewise, when it comes to Coco-Cola, the secret is far more valuable to the company than it would be to anyone else. Nobody could manufacture coke on the same scale, so they would end up charging more - and why would anyone bother buying coke that tastes just like Coca-Cola but costs more?
The recipes are not kept in vault for security, but to help reinforce the value of the brand. Similarly you could argue that selling Big Mac special sauce for almost £12,000 is gong to achieve exactly the same thing.
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