Sniffing out which plant-based burgers smell the most like real beef

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Summer barbecues would not be the same without the delicious aroma of burgers on the grill. Many people are open to considering plant-based alternatives as long as they are similar in taste, texture, and odor to real beef. Researchers have found that some plant-based burgers smell very similar to real beef when cooked, but other products have much more work ahead of them.

Today, the researchers will present their findings at the American Chemical Society's fall meeting.

LiLi Zyzak Ph.D. is the principal investigator of the project. She says that people have become more open to plant-based alternatives over the past few years due to increased awareness about the impacts of meat production on climate changes and the shortages of meat during the pandemic. There are many products on the market, and food companies do interesting research. But nobody publishes anything, because it's trade secrets.

Plant-based meat products are available since more than 20 years. However, the early versions were quite different from traditional meat. Many food companies have spent years researching how to make protein from plants like soy and pea taste more similar to beef. Impossible Foods is a newer company that competes with industry giants like Tyson Foods, Nestl, and Kellogg's.

Although raw hamburger is very odorless, cooking it can release hundreds of volatile compounds that add flavor and aroma. Zyzak from Eastern Kentucky University says, "The problem is with plant-based hamburgers is that the plant proteins themselves contribute a strong smell." Pea protein, for example, smells like fresh cut green grass so companies need to find a way of masking that smell. Some companies use strong seasonings. The other challenge is to determine the right blend of vegetable oils that mimics the fatty meat smell.

Zyzak admitted that she is a big fan of meat and potatoes, but she was interested in how plant-based burgers compare. She says, "We wanted to give consumers a better idea of what's available so they can make informed choices at the grocery store."

Researchers analyzed the aroma compounds that were produced when cooking real hamburgers and eight popular plant-based burger brands. They first cooked the burgers, and then evaluated their aromas using five descriptors, including meaty, fatty and buttery, sweet, and roasted. They then used gas chromatographymass spectrum (GC/MS) and olfactometry combined to match the aromas to specific odor compounds. The team injected volatiles made from cooked burgers into the GC/MS instrument to separate the compounds. A portion of the sample was sent to a sniffing port. Here, a person would click a button when they detected a particular odor. The person used a microphone to describe the smell of each descriptor (e.g., buttery). MS analyzed the remaining sample and identified specific compounds that were associated with the smells detected by the person.

The team identified the compounds responsible for the differences between plant-based burgers and traditional hamburgers. The Beyond Burger from Beyond Meat was the closest to the actual hamburger odor. It had meaty, fat and grilled meat characteristics due to the compounds 1-octen-3ol, nonanal, and it was still quite different from the real deal. One brand was closest to raw hamburger. However, upon cooking it, it developed a yeast-like or bread-like smell with higher levels propionic acid and methyl butanals. Many other brands used heavy seasonings to release strong barbecue-sauce or garlicky aromas.

Zyzak hopes to eventually use the knowledge she has to create a mix of odor compounds that closely resemble hamburger aroma. A startup company is also helping her to collect samples of cell-based meat, which is meat produced in animal cells in fermentation tanks. She plans to compare these samples with regular burgers.

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Additional information: ACS Fall 2021, Investigation into the sensory and analytical differences between traditional hamburgers and their plant-based counterparts.