Sniffing out the best plant-based burgers

Researchers have been sniffing out the best plant-based burgers on the market to see if they can come close to the mouth-watering aromas of real meat burgers. They found that the aromas of a couple of plant-based burgers come close to the real deal when they are cooking, though other products still have a long way to go.

The researchers presented their results at the American Chemical Society (ACS) Fall 2021 hybrid meeting, which is being held virtually and in person from 22–26 August, with on-demand content available from 30 August until 30 September.

Raw hamburger has very little odour, but cooking it releases hundreds of volatile compounds that contribute to taste and aroma. “The problem with plant-based burgers is that the plant protein itself contributes a strong odour,” said LiLi Zyzak, PhD, the project’s principal investigator from Eastern Kentucky University. “For example, pea protein smells like green, cut grass, so companies have to find a way to mask that aroma. Some use heavy seasonings.” Another challenge is determining the correct blend of vegetable oils to mimic the fatty meat smell.

In recent years, many food companies have done extensive research on how to make proteins from plants such as soy and pea taste more like beef. Newer companies, such as Impossible Foods and Beyond Meat, are competing with industry giants such as Kellogg’s, Tyson Foods and Nestlé in this market.

“There are a lot of products out there, and food companies are doing interesting research, but nobody ever publishes anything because it’s a trade secret,” Zyzak said.

Therefore, the researchers analysed the aroma compounds produced by cooking real hamburger and eight popular brands of plant-based burgers to see how they stack up.

As a first step, they cooked the burgers and evaluated the aromas using five descriptors: meaty, fatty, buttery, sweet and roasted. Then, they used gas chromatography–mass spectrometry (GC/MS) combined with olfactometry to correlate the aromas with specific odour compounds.

To do this, the team injected volatiles from the cooking burgers into the GC/MS instrument, which separated the compounds. Some of the sample was diverted to a sniffing port, where a person clicked a button when they smelled an individual odour. Using a microphone, the person said which of the five descriptors it smelled like (for example, “buttery”). The remaining sample was analysed by MS, and the researchers correlated specific compounds with the aroma smelled by the person at a certain time.

The team then identified the compounds that caused the plant-based burgers to differ from traditional hamburger. Of the alternatives tested so far, the Beyond Burger from Beyond Meat most closely resembled the odour profile of actual hamburger, with meaty, fatty and grilled meat characteristics from the compounds 1-octen-3-ol, octanal and nonanal; however, it was still significantly different from the real thing. Another brand had the closest appearance to real raw hamburger, but upon cooking, it had a yeast- or bread-like odour, with higher levels of methyl butanals and propionic acid. A number of the other brands had heavy seasonings that released strong garlicky or barbecue sauce-like aromas.

Ultimately, Zyzak would like to use what she’s learned to produce a mixture of odour compounds that closely mimic hamburger aroma. She’s also working with a start-up company to obtain samples of cell-based meat (lab-grown meat that is produced by animal cells in fermentation tanks), which she plans to compare with plant-based and regular burgers.

The researchers acknowledge support and funding from the Eastern Kentucky University-Funded Scholarship Grant program and Eastern Kentucky University’s New Science Building equipment funds.

The ACS Fall meeting features more than 7000 presentations on a range of science topics.

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