Climate Burgers: Breaking Down The Science of Plant-Based Meat

轉載自UCLA100


“Have you tried these new plant-based burgers that taste like beef?”

“What is plant-based meat made out of?”

“Why not just eat regular meat?”



Plant-based meat has exploded in popularity in recent months, popping up in fast-food restaurants and grocery stores all over the country. As millions of people try it for the first time, they’re having conversations and asking a lot of questions.

To better understand these foods, we talked to two UCLA experts: Amy Rowat, associate professor of integrative biology and physiology, and Jennifer Jay, professor of civil and environmental engineering. Here, Rowat and Jay break down the science of how plant-based meat is made, and show us how these new burgers can help fight climate change.



Engineering meat out of plants

The success of plant-based burgers depends on how much they look, smell and taste like meat. So how do companies like Impossible Foods and Beyond Meat pull this off?

Amy Rowat specializes in answering this kind of question. She uses food to teach scientific concepts — undergraduate students eat apple pie on the first day of her class to learn how butter’s molecular structure creates a perfectly flaky crust. Rowat leads UCLA’s Rowat Lab and helps organize Science&Food, a series of popular public lectures at UCLA featuring chefs and food critics.

Rowat points out that tens of millions of dollars have been poured into research and development at companies like Beyond and Impossible — all with the goal of satisfying each of our senses.

The first impression of an Impossible or Beyond burger is that it has the same pink color as raw meat. To achieve that color, engineers use two different methods. “Some products use molecules from plants like beets, which are naturally red,” Rowat says. “Others, like the Impossible burger, use industrial fermentation. That’s a fancy way to say they use microbes to produce a protein that gives the red color. It’s very similar to hemoglobin, which gives the red color to blood.”

When you touch a plant-based burger patty, it has a similar texture to beef. “Using technology to organize how all these molecules are arranged in the burger is an important component for the texture,” Rowat says. “Extrusion is a popular method to get the fiber structures, used famously by Beyond Meat.” Beyond’s extrusion machines heat and pressurize the plant proteins to realign their structure, creating that meaty texture.


Most importantly: Plant-based meat has to deliver the same taste and melting mouthfeel of a beef burger. “Meat has a lot of saturated fat, which melts at a higher temperature,” she says. “So when you cook it, their liquids will ooze out and melt. It feels delicious on your tongue.” To create that effect in plant-based burgers, coconut oil is a popular ingredient.

While the science and technology is impressive, they’re not what Rowat gets most excited about. For her and Jennifer Jay, the most exciting part is plant-based meat’s environmental impact.

How plant-based meat can help fight climate change

Many people aren’t aware of the impact diet has on the environment, especially as a contributor to climate change. According to the United Nations, livestock accounts for 15% of global greenhouse gas emissions — a larger source of emissions than transportation. Beef alone accounts for a whopping 41% of livestock emissions.

Jay is an expert in how food impacts our environment. She works in UCLA’s Institute of the Environment and Sustainability, and also runs the website Meals for the Planet, which publishes environmentally friendly recipes and related news.

Jay explains that animals are an especially energy-intensive food source. “When you feed animal feed to an animal, most of the calories don’t go toward making meat that we would eat,” she says. “Most of the calories go toward maintaining the animal… and a lot of the energy that you’re giving the animal doesn’t become meat. So part of the carbon footprint comes from just the additional food that you need to grow for the animal.”

“The other part is that ruminant animals have another mechanism for introducing greenhouse gas equivalents,” she says, “which would be the fact that they produce methane as part of their natural digestion.” In other words, when cows belch and pass gas, they produce one of the most potent greenhouse gases driving climate change.

Jay is particularly good at putting the environmental impact of food into simple terms. For example, she says that switching one plant-based burger for one beef burger saves the same amount of CO2 emissions as driving the average American car for 12 miles.

She breaks down the Paris Climate Agreement into simple, personal terms as well. To meet America’s emission targets, she says, every American must keep their emissions under 2,730 grams CO2e (carbon dioxide equivalents) per day. If you substituted a beef burger for a plant-based one, you save 3,300 grams CO2e — more than the daily reduction rate.

Solving climate change starts with small choices

Rowat and Jay make different personal choices when it comes to food. Rowat eats meat on occasion, while Jay eats a plant-based diet. Both understand that meat is an important part of many people’s diets. “People have an intrinsic drive to eat meat,” Rowat says, “and there are cultural and religious preferences. Food is very personal. It’s a very personal choice.”

Even if meat eaters try only one plant-based burger, Rowat and Jay are thrilled that people are taking the opportunity to learn about food and its impact on the environment. With global population projected to reach 10 billion by 2050, food — and beef, specifically — will be a bigger and bigger contributor to climate change.


Over time, small choices can add up to a larger impact. For example, switching a beef burger to a plant-based once a week for a year is the CO2 equivalent of driving a car for 624 miles. Climate change doesn’t have to be solved by politicians and international agreements alone. It can start with each of us making simple, informed choices — like ordering a burger — in our day-to-day lives. With knowledge, we can serve a sustainable future.


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