Turning Fast Food Waste into Flavor: My McDonald’s Garum Experiment

Why Did I Do This?

Food waste is a colossal problem in our world, and it happens at every level – from our homes to restaurants to resorts. Roughly 40% of all food in the United States is thrown away each year, amounting to about 119 billion pounds of waste and a $408 billion lossmashed.com. The restaurant industry is a major contributor; one study found about 40% of all food waste comes from restaurants, grocery stores, and food service combined, with restaurants alone accounting for $162 billion in waste-related costs annuallymashed.com. These numbers floored me. How can so much food be tossed out while millions go hungry?

Even a highly optimized operation like McDonald’s is not exempt. In fact, McDonald’s employees have to fill out lengthy “waste sheets” multiple times a day to track how many products are thrown away and how much money that representsmashed.com. Seeing an itemized log of wasted cheeseburgers ($0.45 lost each), Big Macs ($0.87 each), etc., really drives home how much perfectly edible food ends up in the binmashed.com. And it’s not just a financial loss – think of the environmental cost. Food waste is estimated to contribute 8–10% of global greenhouse gas emissions (in fact, wasted food emits 5× more CO₂ than the aviation industry)wrap.ngo. When we dump food in landfills, it’s not only the resources used to produce that food that go to waste (water, energy, labor, land), but the rotting food also releases methane, a potent greenhouse gas. By some estimates, if food waste were its own country, it’d be the third-largest emitter of greenhouse gases after China and the U.S.wrap.ngo. It’s clear that wasting food isn’t just a missed opportunity to feed people – it’s wrecking the planet too.

Confronted with these facts, I felt I had to do something, even if only on a personal experimental scale, to illustrate a different path. I’m a foodie and a fermentation geek, so I asked myself: Can we take something everyone recognizes – say, leftover fast food – and turn that waste into something useful and delicious? This project became my way of exploring that question and sparking conversation. It’s not about shaming anyone for enjoying a burger, but about rethinking what we consider “trash”. If we could turn even McDonald’s leftovers into a tasty new ingredient, it would prove a point: with creativity, today’s trash could be tomorrow’s treasure.

Why McDonald’s (and Why Coke)?

I chose McDonald’s for this experiment very deliberately. McDonald’s is an icon – it’s practically everywhere, and almost everyone has eaten there at least once. The chain serves around 68 million customers a day, which is roughly 1% of the world’s population every single dayentrepreneur.com. That sheer scale means McDonald’s has an enormous impact – on diets, on economies, and yes, on the environment. With great scale comes great responsibility; even small percentages of waste at McDonald’s can translate to giant absolute quantities. For example, McDonald’s globally reportedly produces about 75 burgers every second, which is about 6.5 million burgers per daymedium.com. Now, thanks to their “fresh food” policies (where items have strict holding times), roughly 5% of those burgers end up thrown out instead of eaten. That works out to roughly 200,000 burgers tossed in the trash every day around the worldmedium.com just because they weren’t sold within their 10-minute shelf-life. Over a year, that could be on the order of 73 million burgers wasted – an astonishing figure to wrap my head around. And that’s just the burgers, not counting mountains of fries, chicken nuggets, and other items that meet a similar fate.

McDonald’s makes a compelling case study because it highlights the complexity of the food waste issue. On one hand, this company feeds an astonishing number of people (some call it the world’s unofficial largest kitchen). It provides affordable meals to families who might not always have the time or money for alternatives – and let’s face it, not everybody can afford or access healthy, home-cooked organic meals all the time. In that sense, McDonald’s has a positive impact by providing convenient, inexpensive food. On the other hand, that very system that produces consistent Big Macs at scale also produces consistent waste. Burgers are made ahead and held only briefly; fries are hot for a few minutes before they’re past their prime. The result: a lot of perfectly good food gets binned in the name of freshness and efficiency. It’s a tangled trade-off – food safety and quality vs. waste. And it’s not a problem with an easy one-size solution.

I also roped Coca-Cola into this project. Why Coke? Well, if you’ve ever looked into a restaurant trash can, you’ll see it’s not just solid food getting wasted – it’s beverages too. Think of all those half-full cups of soda that get tossed, or the excess soda mix that restaurants sometimes dump out. I’ve seen entire buckets of flat Coke being thrown away at the end of a day. Soft drinks are essentially sugar water, and when thrown out en masse they’re another facet of waste (and a sugary sticky mess at that). Since I wanted my experiment to be 100% in the McDonald’s universe, I decided: instead of using water in my fermentation (as one normally would), I’ll use Coca-Cola. This way, every ingredient in my project – from the meat to the bread to the liquid – was something obtained from McDonald’s. It’s a bit tongue-in-cheek (let’s be honest, Coke isn’t exactly a health drink), but there was logic behind it. Coke contains a ton of sugar, which in fermentation can act as fuel for microbes. If I’m trying to grow a community of beneficial microbes (more on that soon), why not give them some sugar and see what flavors emerge? Plus, I just loved the symbolism of it: the quintessential fast food meal (a burger, a Coke, and a bun) being reborn as something entirely different rather than ending up in the dumpster.

So ultimately, I picked McDonald’s and Coke because they are familiar, widespread, and emblematic. This isn’t some obscure foodie project with rare ingredients – it’s literally drive-thru leftovers. My hope was that by using such an everyday example, people would instantly get what I’m doing and why. If we can successfully transform McDonald’s waste into a gourmet ingredient, that’s a story I think everyone will find intriguing (or at least entertaining!). And if it flops… well, at least I tried, and we’d learn something in the process.

From Ancient Rome to My Kitchen: What is Garum?

To tackle this challenge, I decided to use the power of fermentation – specifically a type of ferment inspired by the ancient Romans: garum. If you’re not familiar, garum is basically an ancient fish sauce, a fermented condiment dating back to the Roman Empire. The Romans, and even civilizations before them (the Greeks, Phoenicians, etc.), had a clever way of preserving fish and extracting flavor: they would take the guts and trimmings of fish, mix it with a lot of salt and herbs, and let it ferment under the hot sun for months. The result was a potent amber liquid – garum – which they used like we use ketchup or soy sauce todayfoodandwine.comfoodandwine.com. It was umami bomb before the word umami existed: full of savory amino acids from all that broken-down fish protein. (In fact, one Roman scholar, Pliny the Elder, poetically called garum an “exquisite liquid” – though others described the smell in less flattering terms!)

So why did I think of garum for a McDonald’s project? For one, garum was historically a zero-waste solution. It literally took the parts of fish that would otherwise be thrown out – heads, innards, bones – and turned them into a valued food product. In that ancient context, it was about maximizing resources. Fast-forward to today: fermentation enthusiasts and cutting-edge chefs have resurrected garum for both its flavor and its sustainability. Modern garums don’t always use fish; you can ferment almost any protein or rich scraps in a similar way. World-renowned restaurant Noma in Copenhagen, for example, led a revival of garum by fermenting things like mushrooms, beef, and even insects with salt and koji (a Japanese fermentation culture) to create new sauces. Part of the appeal is flavor – garums can taste amazing – but it’s also about reducing food waste by repurposing scraps of vegetables, fish, or meat that would otherwise be discardeditalysegreta.com. As Food & Wine magazine put it, chefs love garum because the process of heavily salting a raw protein to extract its juices both creates deep flavor and minimizes wastefoodandwine.com. Those are exactly my goals here!

Let me explain the science in simple terms: When you salt down organic matter (be it fish guts or, say, burger meat), two things happen. First, the salt draws out moisture and creates a brine in which microbes and enzymes can move around. Second, the high salt environment prevents bad bacteria from spoiling the food. Only salt-tolerant microorganisms (the kind that make tasty ferments) can thrive. Traditionally, in Roman garum, the enzymes that did the hard work came from the fish innards themselves (things like digestive enzymes in intestines would break down proteins). In my case, I didn’t have fish guts in a Big Mac (thank goodness), so I introduced a starter culture known as koji. Koji is essentially a fungus (Aspergillus oryzae) grown on grains – it’s the same friendly mold the Japanese use to make soy sauce, miso, and sake. Koji is a powerhouse because it produces protease enzymes that break proteins apart into amino acids (which amplify that savory umami flavor)nature.com. In other words, koji can do the job that fish guts did for the Romans, but in a cleaner, more controlled way. Using koji in garum-making is now a common practice in modern fermentation projects – it supercharges the breakdown of whatever base ingredients you’re fermenting.

So, my plan was to treat McDonald’s burgers kind of like the Romans treated fish: I’d chop them up, mix them with salt and a bit of liquid, add the koji to kickstart the fermentation, and then keep the mixture warm for long enough that it decomposed in a controlled, delicious way. It sounds wild – and it is – but the logic tracks. We’re essentially harnessing natural processes to turn trash into tasty treasure. This isn’t a totally new idea either; many culinary traditions have fermentation techniques born from preservation or waste avoidance. (Think of kimchi preserving excess vegetables, or how cheese was a way to save surplus milk.) In my mind, garum-style fermentation was the perfect method to apply to fast food leftovers: it’s ancient wisdom meets modern waste challenges.

The Experiment: Fermenting a McDonald’s Meal

Alright, so here’s what I actually did. I went out and bought a standard McDonald’s meal: several 100% beef patties (the kind used in Big Macs and Quarter Pounders), a bunch of buns (for carbohydrates – and because they’re part of the waste stream too), and a large cup of Coca-Cola. Yes, that’s literally the ingredient list. To this, I added only two non-McDonald’s items: salt (a lot of salt) and koji culture. The goal was to use only McDonald’s-derived food in the ferment, keeping it as authentic (and amusing) as possible. By replacing any normally added water with Coca-Cola, I ensured that even the liquid component was on-brand McD’s.

First, I prepped the ingredients: I crumbled the beef patties and buns into small pieces. The smaller the pieces, the more surface area for the microbes to work on, so breaking everything up helps. The mixture looked… well, like a panzanella salad from hell – bits of burger and bread everywhere. I then poured in a generous amount of Coke, just enough to create a wet slurry. Immediately, the kitchen smelled bizarre: sweet caramel cola mixing with burger grease – a preview of the weird fusion to come.

Next, I inoculated this soupy mess with koji. In practice, this meant adding a measured amount of dried koji rice (rice grains that are fully colonized by Aspergillus oryzae mold). Koji is usually white and fluffy on the grains, a bit sweet smelling. Mixing it into the Coke-burger soup, I had a moment of “what on Earth am I doing?” But I reminded myself: this mold is my friend – it’s going to produce proteases and amylases (enzymes that break down protein and starch) and create flavors. Finally, I stirred in the salt. And I mean a lot of salt – roughly 10-12% of the weight of the entire mixture was salt. This high salinity is crucial; it’s what keeps the wrong bacteria from taking over and turning the project into a rotten mess. At 10%+ salt, only hardy microbes (like certain Bacillus species or halophilic lactic acid bacteria) will survive, and those are typically the flavor-makers we want. For context, this salt percentage is similar to what you’d find in a soy sauce or fish sauce fermentation. It’s extremely salty, but remember, we use the resulting garum in drops and dashes, not gulps.

With everything mixed, I sealed the concoction in a fermentation vessel (a sturdy glass jar) and set it in a warm environment around 60°C (140°F). I’m lucky enough to have a temperature-controlled fermentation chamber (basically an incubator) for projects like this. Traditional Roman garum would ferment in the sun at ambient outdoor temps, but modern garum makers often go hotter to speed up the process. 60°C is a magic number – it’s warm enough to turbo-charge enzyme activity and fermentation, but not so hot as to kill the koji or other microbes. I often describe this as “low and slow cooking, but done by microbes.” Then came the hardest part: waiting. I let the jar ferment for about 6 weeks, occasionally checking on it (and yes, occasionally burping the jar to release gas buildup – you do NOT want a glass jar exploding burger-garum all over your pantry!).

Over time, the transformation was remarkable. After the first week or two, the mixture started to brown and liquefy. The enzymes were breaking down the meat proteins into peptides and amino acids, and the buns (which are mostly starch) were likely being broken into sugars by the amylases. The smell, which initially was like someone spilled a Coke in a McDonald’s kitchen trash can, evolved gradually. Around week 3 or 4, it started smelling oddly appetizing – a rich, meaty aroma with a sweet undertone. There were hints of soy sauce, which makes sense, since soy sauce is also a product of protein breakdown (soy proteins in that case) plus caramelized sugars. I’d take a clean spoon, dip into the ferment and dab a tiny drop on my tongue every now and then (yes, I dared to taste it mid-ferment!). It was incredibly salty (no surprise there), but I could already sense umami, and even a kind of deep sweetness coming along.

By the end of the sixth week, the McDonald’s garum was ready to be unveiled. I strained out the solids, pressing them to extract every bit of liquid. What I bottled was a dark amber-brown liquid, almost the color of soy sauce or Worcestershire sauce, with a consistency slightly more viscous than water. It was clear-ish (not a puree or sludge; the solids were largely broken down or filtered out). To anyone who didn’t know, it looked like some kind of fancy vinegar or fish sauce – nothing about it screamed “Big Mac” visually.

The Taste Test: From Trash to “Umami Gold”

Now for the million-dollar question: How did it taste? Honestly, I was prepared for it to be awful – this whole thing could have been a spectacular (and smelly) failure. But to my delight, the garum turned out shockingly delicious. The aroma was intense: think charred beef and yeasty bread and a whiff of sweet cola all melded together. And the flavor? It’s hard to describe because it’s unlike any single familiar sauce, but I’ll try: On the tongue, it first hits with a powerful saltiness (akin to soy sauce or fish sauce, as expected). Then it blooms into a deep savory richness – that’s the umami from all the broken-down beef protein. There’s a touch of sweetness in the middle, almost like a salted caramel note (no doubt thanks to the Coke and the toasted sugar from the buns). And the finish has a lingering grilled meat flavor with a subtle cola-spice aftertaste (you know that slightly herbal, vanilla-like note in Coca-Cola? I could swear there was a ghost of that in the background).

In short, the McDonald’s garum is like a steak sauce meets soy sauce with a twist of Coca-Cola. Or as I’ve jokingly described it to friends: imagine if a barbecue glaze and a soy sauce had a baby, and that baby grew up drinking Coke 😅. One comparison I made in my notes was “salted caramel soy sauce, with a hit of grilled steak and cola.” It sounds crazy, but it’s genuinely mouthwatering if you’re into complex umami flavors. A chef friend of mine dipped a spoon in and said, “I’d totally cook with this.” That blew my mind – we went from dumpster-bound Big Mac to gourmet seasoning.

Beyond just taste, what excites me is how this sauce can be used. I’ve since tried it as a seasoning in a few dishes, and it’s a knockout. A few dashes in a stir-fry can elevate the savoriness without anyone knowing your secret. I brushed a little on a steak as it rested, and it was like instant umami amplification. Even a vegetarian friend (brave soul) sprinkled a bit on roasted mushrooms and was amazed at how much it intensified the flavor (mushrooms plus this kind of meaty garum = magic). Essentially, I now have a zero-waste umami bomb in my pantry that started life as fast-food rubbish.

I also want to note: this isn’t totally unprecedented – chefs in the modernist cuisine space have been doing “disgusting-sounding” ferments like burger garums or pizza garums in recent years, mostly as experiments to see what happens. I found out after my experiment that a restaurant in Denmark had toyed with a hot dog garum and others have tried fermenting various junk foods. So I’m not the only mad scientist here. But as far as I know, combining an entire McDonald’s meal (burger + bun + Coke) into a garum hadn’t been documented before. It’s pushing the concept to an extreme, and that’s partly why I love it – it really underscores the message that anything organic can be a resource if treated the right way.

Reflections: Waste Not, Want Not

This whole project has been eye-opening and, frankly, inspiring. It started as a wacky “what-if” idea, but it ended as a tangible example of circular thinking in food. The truth is, not everyone is going to ferment their leftovers – I don’t expect families to start brewing Big Mac soy sauce in the garage (and please, if you do, be careful and use lots of salt!). But on a broader level, I hope this experiment gets people thinking about waste in new ways. We’re so used to tossing food that’s a day old or not perfectly fresh. Perhaps we’ll never get to a point where McDonald’s is brewing garum from its unsold burgers at each location (wouldn’t that be something, though – McGarum dipping sauce next to the ketchup!). However, maybe large chains could implement more creative waste-reduction strategies, whether it’s donating unsold food (laws like the Good Samaritan Food Donation Act protect donors from liability, though many companies still hesitate) or repurposing it into animal feed, compost, or industrial products. In McDonald’s case, they actually did donate 9 million pounds of excess food during the pandemic to food banksmashed.com – so there is precedent for helping rather than heaping food into landfills.

On the home front, we can take a cue from the ethos behind this experiment without necessarily doing extreme fermentations. Think about the edible things you throw out: vegetable peels, stale bread, that extra portion of pasta no one ate. Can some of that be given a second life? Vegetable scraps can make great stock. Stale bread can become bread pudding or breadcrumbs. Leftover bits of many meals can be turned into a soup or casserole. And for the more adventurous – yes, you can ferment at home in simpler ways (yogurt, pickles, sauerkraut) to extend the life of foods and add nutrition. The point is to be creative and conscientious. If a junk food Frankenstein sauce like my McDonald’s garum can be not only safe but delicious, then surely a lot of other less-crazy ideas for reducing waste are possible too.

My McDonald’s garum experiment might sound like a fun gimmick (and admittedly, it was fun and a bit gimmicky), but I truly see it as a food system microcosm. We have on one side a symbol of mass production and waste, and on the other an age-old symbol of preservation and resourcefulness. Bringing them together was my way of reconciling those extremes – showing that maybe our future food systems can take the efficiency of something like McDonald’s but infuse it with the sustainability of something like garum. Imagine if big fast-food companies applied even a fraction of the ingenuity ancient peoples did when food was scarce and precious. Considering the scale of McDonald’s – remember, 1% of the world eats there dailyentrepreneur.com – even minor improvements or innovations could have an outsized impact.

At the end of the day, this was one small jar of sauce from a few burgers. It’s not going to solve world hunger or climate change on its own. But it’s a story now – a conversation starter. When I show people the jar and let them smell or taste it, their eyes widen and they start asking questions. “You made this from WHAT? How? Why?” – and that’s my opening to talk about food waste, about fermentation, about thinking differently. I’ve found that tackling serious issues doesn’t always require dour sermons; sometimes you can engage folks with a sense of wonder or absurdity (like turning Big Macs into gourmet sauce) and that actually sticks with them more.

In conclusion, I’ll say this: food is only waste if we waste its potential. By channeling a bit of ancient wisdom and modern science, I was able to unlock flavors from trash and learn a ton in the process. Will garum made from burgers ever be on store shelves? Probably not – and that’s okay. The real takeaway for me, and I hope for anyone reading this, is that we need to reimagine our relationship with leftovers and surplus food. Whether it’s at the scale of a multinational corporation or in our own fridges, there’s room to do better – to waste less, and maybe even discover something new and amazing along the way.

Next time you find yourself with a table of uneaten food, or you’re about to dump out that half can of soda, think of this crazy experiment. It might inspire you to save it, transform it, or at least smile at the absurd amount of effort I put into making a sauce out of a Happy Meal. If I can ferment McDonald’s into a tasty sauce, what else can we do if we put our minds (and microbes) to it?

References

1. Amberly Mckee, “The Ridiculous Form That Shows How Much Food McDonald’s Wastes,” Mashed.com, July 1, 2023. (Cites 40% of America’s food is wasted each year ≈119 billion pounds, $408 billion, and notes 40% of food waste comes from restaurants/grocery/food service; discusses McDonald’s employee “waste sheet” and items/costs)mashed.commashed.com.

2. Entrepreneur – McDonald’s Facts: McDonald’s feeds ~68 million people per day (about 1% of world population) and sells ~75 burgers per secondentrepreneur.com.

3. Talayeh Dehghani, “UX solution for McDonald selling service to reduce food waste,” Medium.com, Oct 20, 2021. (Notes McDonald’s produces 6.5 million burgers per day and ~5% are wasted; ~200,000 burgers thrown out daily worldwide due to 10-min shelf-life policy)medium.com.

4. WRAP (Waste & Resources Action Programme) Press Release, “Food waste contributes 10% to global emissions…”, Nov 13, 2024. (Food waste = 8–10% of global GHG emissions; if it were a country, would be 3rd largest emitter; food waste emits 5× more than aviation)wrap.ngowrap.ngo.

5. Italy Segreta Magazine, “Garum – The Ancient Roman Condiment Making a Comeback,” (undated). Discusses chef René Redzepi’s work at Noma: how fermentation can create intense flavors while reducing food waste by repurposing scraps of vegetables, fish, or meatitalysegreta.com.

6. Maggie Hennessy, “Why Chefs Have Loved Garum Since Ancient Times,” Food & Wine, Oct 19, 2022. (Explains garum’s history and modern revival; fermenting protein with salt extracts liquid and minimizes waste; compares garum to Asian fish sauce; notes chefs now apply the term to all sorts of fermented sauces using diverse ingredients and often koji cultures)foodandwine.com.

7. Lisa Melton, “Noma: from grasshopper brews to age-old ‘garum’,” Nature Biotechnology 40, 1704 (2022). (Describes Noma’s experimentation with garums; notes that Japanese koji (Aspergillus oryzae) mold produces similar enzymes to fish guts for breaking down proteins, enabling fermentation of various ingredients)nature.com.

8. McDonald’s UK, FAQ – “On average how much food waste is being separated… per week?”, May 22, 2018. (States that in their kitchens they separate around 180 kg of food waste per restaurant per week for anaerobic digestion/composting, rather than landfill)mcdonalds.com.

9. Mashed.com (McKee, 2023) – Customer and employee reactions on Reddit regarding McDonald’s waste. (Customers wish McD would donate unsold food; employees upset they must throw it out rather than take it home; notes Good Samaritan Food Donation Act protects donors from liability, and McDonald’s did donate 9 million lbs of food during pandemic that “otherwise might’ve gone to waste”)mashed.commashed.com.