behind the impossible burger: heme, yeast, and sustainable eating
- how & why
- Sep 23, 2019
- 7 min read
Everyone and their mom has heard about the Impossible Burger, the incredible plant-based protein product that looks, tastes, and even "bleeds" like a real ground beef patty. The product, generated by Impossible Foods, has been available at a variety of restaurants and will soon be available in grocery stores. But how does it work? How can we have a plant-based product that looks, smells, feels, and tastes like a meat product? These questions bring us into the growing field of food science. As the population of Earth grows, and as we exhaust existing food sources, we need to invest more research into food. And that's exactly what brands like Impossible Foods have been doing.
Impossible Foods set out to create the most meaty meatless burger they could, utilizing the scientific tools available to them. First, they started by running a normal beef burger through a gas chromatography mass spectrometer, which is basically like a smell-o-vision dictionary for proteins. Let's break that down.
Let's say you have a book, written in a different language than the one you speak. You want to translate the book, and identify each word, but you can't read the language. So while you know there are definitely words in there, you have no clue what the words mean or which one is which. So, to figure it out, you rip out a page of the book and scan it into a computer, which translates the words for you and arranges them by their internal properties: like length, word type, or sound. This is super helpful because some of these words are new words that you have never heard before. Now you know which words were on the page, you have new info on some new words, and can understand the words relationships to one another (i.e. the word "the" is shorter than "burger" and that "pink" and "drink" rhyme).
That's *basically* what the scientists at Impossible Foods did to figure out what components to add to their plant-burger. They heated up a sample of a normal beef burger (that's the gas part) and sent the burger smell through a mass spectrometer, which separates the proteins within the sample by their mass-charge ratio (like how our dictionary-scanner arranged our translated words). Then, they looked for plant-based proteins that mimicked the identified beefy proteins in their structural components, like size, shape, mass, and charge. They hoped that identifying the molecular components that makes meat smell/taste meaty, they could use matching planty components to make their burger look as beefy as The Rock, even though it's only made of plants. Their application of smell-o-vision allowed them to select the best plant ingredients to match the burger.
One of the meatiest components of meat is heme . Heme is an iron containing molecule that occurs naturally in almost every single living species on this planet. You might know heme from one of its most common forms: hemoglobin, the protein that allows our blood to carry oxygen to all of our muscles, and makes our blood red. Heme proteins are also components of myoglobin, a muscular protein that binds oxygen and iron and is a huge component of the meat we eat. These heme proteins are one of the most "meaty" parts of meat: giving texture and that slightly metallic bloody taste to your favorite BBQ meal. In order to create the most burger-y plant burger, Impossible Foods turned to a heme protein found in soybean plant roots called leghemoglobin. Leghemoglobin has a molecular structure that is very similar to that of myoglobin, leading scientists at Impossible Foods to try it out in their plant-based meat products. And it was delicious. It's the leghemoglobin that gives their Impossible Burger the red color and makes it "bleed", as well as providing some taste components.
However, there was one big problem. Harvesting enough leghemoglobin from soybean roots for the growing demand for vegan food products would require so so so so so so much soy. Too much soy. So, they turned to an alternative solution: genetic engineering.
Now that the sirens have stopped going off in your head, lets actually break down what that means. Genetic engineering refers to the deliberate modification of the characteristics of an organism by manipulating its genetic material, or DNA, which is actually a pretty broad definition. Changing a single base pair of DNA or deleting an entire gene or rearranging a chromosome are all examples of genetic engineering. So then, what's a genetically modified organism, or GMO? A GMO is any organism whose genetic material has been altered using these genetic engineering techniques. This is also vague and can basically include any genetic alteration that could not occur through natural processes such as mating. The types of modifications done to these organisms have a huge range, from inserting genes from different species, to rearranging, to deleting genes. AND BEFORE YOU FREAK OUT, GMOs do not have the negative health consequences that they seem to carry in the media. Eating a GMO food will *not* affect your own genetic material.
Ok, so back to the børgers. We know we won't be able to extract leghemoglobin from its natural source, soybean roots, because we would need almost an entire football field of soybeans to harvest just 2.2 lbs of leghemoglobin. Knowing this, the researchers at Impossible Foods decided on a well-known and well-established solution: getting microorganisms to do the hard work for us. The researchers inserted the instructions (genes) for making leghemoglobin into a harmless yeast, Pichia pastoris. The yeast, now with all of the instructions for making leghemoglobin, will grow and divide and produce tons and tons of leghemoglobin. (an interesting side note: technically, the Impossible Burger is *not* a GMO, as it is the yeast that has been genetically modified, and we are simply using that product, as opposed to genetically modifying components in the burger itself) Now, instead of cultivating fields upon fields of soybeans, Impossible Foods can produce their burgers with 1/20th of the land and 1/4th of the water required to raise cattle, which is an incredible improvement! As you may know, raising cattle (dairy & meat) is the largest driver of food-related greenhouse gas emissions, and also uses the most water and land compared to any other US diet farming thing.
A semi-recent study (2017) looked at the environmental impact of substituting 10%, 25%, and 50% of ground beef with plant-based meat products at the national scale. They found that even replacing a small proportion of cow meat with plant-based meat would result in substantial reductions in yearly food-related greenhouse gas emissions, water consumption, and land occupation. While this may not perfectly reflect the current diet-based greenhouse gas emissions, any reductions in emissions we can make seems worth it, imo.
But will people actually eat this burger? Do people like it? Would omnivores *actually* replace 10% of their ground beef with this product? Reviews (online and from friends) on the Impossible Burger seem mixed. I've seen people say that it tastes exactly like a burger, is delicious and meaty and they would choose it over everything else. I've heard from meat-eaters that they got an impossible burger by mistake and spit it out. One of my meat-eating friends would totally buy the Impossible Burger over ground beef (if the price was similar enough), but thinks the Beyond Burger tastes gross. One of my vegetarian friends would always prefer to eat veggie burgers (black bean burgers, etc) over the Impossible Burger because they like that taste better.
In an even more interesting twist, studies show that omnivores link vegetarianism and environmentalism to feminine and liberal ideologies, meaning that in many cases, more conservative (and often male) people might choose a less environmentally friendly option in an effort to seem "more manly" (wtf). I cannot believe we live in a time in which people would prefer to NOT bring a reusable bag to a grocery store in an effort to seem "less feminine", especially when our futures are quite literally melting with the ice caps. If you don't believe my interpretation, here is a direct quote (with bolded emphasis by me) from a paper by Dr. Peter Slade, called "If you build it, will they eat it? Consumer preferences for plant-based and cultured meat burgers" :
"Rothgerber (2014) suggests that omnivores use various strategies to relieve their dissonance about meat consumption. Some of these strategies emphasize religious and moral arguments in favour of eating meat – these arguments may become internalized and intertwined with other values. For example, there is a strong link between meat eating and conservative political ideology (Ruby, 2012).
Furthermore, many omnivores link meat substitutes to vegetarianism, which generally connotes femininity, earthiness, and a liberal ideology (Minson & Monin, 2012; Ruby & Heine, 2011; Sadalla & Burroughs, 1981). Although vegetarians are often considered to be morally superior (Dietz, Frisch, Kalof, Stern, & Guagnano, 1995; Ruby & Heine, 2011), many omnivores maintain hostile attitudes towards vegetarians, finding them to be moralistic, self-righteous, and radical (Greenebaum, 2012; Minson & Monin, 2012). Individuals who do not share the stereotypical political values or personality traits of vegetarians may prefer not to eat synthetic meat in order to dissociate themselves from these cultural and individual markers."
The article itself goes on to compare preferences to purchase 1) beef burgers, 2) plant based burgers, or 3) cultured beef burgers (i.e. meat that is grown in a lab). The paper concludes: "Although consumers were told that all burgers tasted the same, there was a marked preference for the beef burger – if prices were equivalent, only 21% of respondents would choose the plant-based burger, and 11% would choose the cultured meat burger", and that these preferences were highly dependent on sex, age, and other factors.
So, now, I guess, it's up to you! What do you think? If you've tried the Impossible Burger, would you replace some of your meat products with it? Do you feel more inclined to do so now that you understand a bit more about the environmental advantages behind it? What's more important: taste, price, being "manly", or environmental impact? Does the fact that it includes genetically modified components change your opinion? If you haven't tried it, do you want to? please let me know what you think in the comments, on instagram, or over email!
disclaimer: I do not work for Impossible Foods, I just thought this was a really cool example of science being used for the environment, to solve the potential food crisis, and genetic engineering.
sources:
Goldstein B, Moses R, Sammons N, Birkved M (2017) Potential to curb the environmental burdens of American beef consumption using a novel plant-based beef substitute. PLOS ONE 12(12): e0189029. https://doi.org/10.1371/journal.pone.0189029
Slade, P. (2018). If you build it, will they eat it? Consumer preferences for plant-based and cultured meat burgers. Appetite 125, 428–437. https://doi.org/10.1016/j.appet.2018.02.030
Comments