ScienceNot yet confirmed elsewhere1 publisher2 min readPublished
Imperial College team gets lettuce and tobacco chloroplasts to make myoglobin
Imperial College London researchers say they got lettuce and tobacco plants to make myoglobin for the first time. Because myoglobin comes from animal tissue, it could give plant-based meat a smell closer to red meat than the soy leghemoglobin Impossible Foods uses.
The Scientist · Science desk
What happened
- Heme, the red pigment found in myoglobin and hemoglobin, can give plant-based meat a meaty flavor and the ability to bleed.
- The team engineered the plants' chloroplasts, the cell structures that typically turn sunlight into food, to make them produce the protein.
- Yeast fermentation is the standard way to make heme as leghemoglobin, and its sterile environment and industrial equipment can be pricey.
Why it matters
- cost Growing the protein is the easy part of a plant route. The saving reaches fermentation's customers only if purification from leaf material is also cheap.
- capability An edible host could shorten the regulatory path, according to Scientific American; a fermentation-derived ingredient gets no such advantage from its host.
- decision A product developer weighing myoglobin against soy leghemoglobin has a smell hypothesis to test and no sensory result to act on yet.
The paper, in Frontiers in Plant Science, turns on where the gene goes [2]. In earlier attempts to make myoglobin in nonanimal hosts such as yeast, the production instructions sat in the nucleus's genome; Groff and her colleagues put them in the chloroplast genome instead and found it could yield more of the protein [6]. Scientific American adds, hedged with a "perhaps", that the plants might make myoglobin more efficiently than animals do [12].
The account does not say how much myoglobin the plants made, how that compares with the nucleus route or with yeast, or whether anyone has smelled the result. We think the smell advantage is the least supported of the promises, because it is argued from where the protein comes from and not from a sensory test.
The cost case comes from outside the study. Adam Leman, a Good Food Institute principal scientist with no role in the research, said: "Row-crop protein production would likely be faster than fermentation-derived production" [8]. He also said: "If existing crop-processing equipment can be used, costs for isolating and purifying a myoglobin-rich fraction could be quite low" [9]. Both are projections with a hedge built in.
Energy gets the same treatment. Scientific American says a more streamlined process could mean less money spent in production and far less energy use [14]. It then cites a figure: 60 percent of agricultural energy use comes from farming and transporting animal products [15]. The figure describes animal agriculture, and the energy used by the lettuce route is still a projection.
What to watch
- Yield data in the paper's full text: myoglobin per unit of leaf, chloroplast route against nucleus route and against yeast.
- A sensory or bleed test of the plant-made protein against soy leghemoglobin, which would turn the smell claim from inference into result.
- Any demonstration that a myoglobin-rich fraction can be purified with existing crop-processing equipment, the condition Leman attached to his cost estimate.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence35
- Adoption
- Insufficient
- Hype gap+35
- Incentives
- Insufficient
- Confidence40
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Lead author Alexia Groff, who worked on the project as a Ph.D. student at Imperial College London, says the researchers got lettuce and tobacco plants to produce myoglobin for the first time.
- [3]
The team engineered the plants' chloroplasts, the cell structures that typically turn sunlight into food, to make them produce myoglobin.
- [4]
Myoglobin and its relative hemoglobin contain heme, the red pigment in blood; adding heme can give plant-based meat alternatives a meaty flavor and the ability to bleed.
- [5]
Impossible Foods uses leghemoglobin, a heme protein derived from soybeans, to flavor its meat alternatives.
- [6]
In previous attempts to make myoglobin using nonanimal sources such as yeast, the production instructions were placed in the nucleus's genome; Groff and colleagues found that adding them to the chloroplast genome instead could yield more of it.
- [7]
Yeast fermentation is the standard method of producing heme (as leghemoglobin), but the sterile environment and industrial equipment needed for manufacturing can be pricey.
- [8]
"Row-crop protein production would likely be faster than fermentation-derived production," said Adam Leman, a principal scientist at the Good Food Institute who was not involved in the study.
- [9]
"If existing crop-processing equipment can be used, costs for isolating and purifying a myoglobin-rich fraction could be quite low," said Adam Leman.
- [10]
Plants are much easier to grow than the sterile, equipment-heavy setup that yeast fermentation needs.
- [11]
Scientific American writes that using myoglobin, which is found in animal tissue, could lead to vegetarian products that look and bleed like red meat and also smell more like it.
- [12]
Scientific American says the chloroplast approach is perhaps producing myoglobin even more efficiently than animals do.
- [13]
Because lettuce is itself edible, lettuce-produced myoglobin could move more easily through the regulatory steps that can slow the path from laboratory to market.
- [14]
Scientific American says a more streamlined process could also mean less money spent in production and far less energy use.
- [15]
Scientific American states that 60 percent of agricultural energy use comes from farming and transporting animal products.
Sources
1 independent publisher whose own reporting we read for this story.
- scientificamerican.comLettuce engineered to produce meat proteins
1 article · October 12, 2026
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