Rubisco, the World’s Most Abundant Protein, Stored in Leaves: The Benefits and Efforts to Produce and Commercialize Leaf Protein Concentrates and Integrated Biorefineries That Can Produce Rubisco and Plant Sugar

 

    Rubisco stands for ribulose-1,5-bisphosphate carboxylase/oxygenase. It is found in every green leaf. It is responsible for photosynthesis.

“From a food-ingredient point of view, it’s one of the best natural proteins out there,” says Slavko Komarnytsky, a biologist at the Plants for Human Health Institute at NC State University. Milne, of Leaft, calls it the “utopia” protein because it has so many good attributes. 

“Every single food company that checks out this protein says, ‘We are in love with it, we want to use it, and we want a lot of it,’" Komarnytsky says, "and this is where the problems come in.”

     Rubisco can be made into a neutral-tasting white powder. It can be gelled and emulsified. There appear to be no allergies to it as there are to soy and dairy. It is easily digestible.

“From a food-ingredient point of view, it’s one of the best natural proteins out there,” says Slavko Komarnytsky, a biologist at the Plants for Human Health Institute at NC State University.

     Rubisco is likely to soar in popularity over the next ten years, according to some in the food industry. Its biggest problem right now is simply a lack of availability. That is due to the difficulty in extracting it and the associated costs. Producers are trying to overcome these problems. The issue is that the protein in leaves makes up only about 3% of their content, compared to soybeans, where protein makes up 80% of the content. Thus, quite a lot of leaves are needed to process into small amounts of Rubisco. There are more issues as well. Leaves often turn brown after harvesting, so they must be processed into Rubisco quickly. Solid and liquid waste is another issue that requires management and costs.

     Alana Samuels in Time writes:

“Companies have tried to juice the leaves as soon as they’re harvested, but it can be difficult chemically to isolate the rubisco and get rid of the green color to make it into the white powder, says Pearce. “The technology is similar to what it was back in the 60s and 70s,” he says.

“Tony Martens, CEO of Plantible, which makes rubisco to sell to food companies, says he partially agrees with this assessment. Though the underlying process of pulling rubisco from leaves hasn’t changed much in half a century, he says, it has become more possible to make white rubisco protein at a commercial scale in part because of updated processing processing technologies.”

     The challenges to commercializing rubisco remain difficult, and whether it will be successful remains uncertain. It does have some emissions benefits, waste benefits, and animal welfare advantages over other forms of protein. To get animal protein, we must grow specific crops to feed the animals. That part is very emissions intensive. Animals also cause a lot of waste runoff.

     Harvesting and protein yield per acre is more efficient for rubisco than for animal protein.

“What we’re doing is skipping the middleman and going directly to the source,” says Milne. He says that by harvesting alfalfa, one of the most common sources of rubisco, and turning it into protein, Leaft is harvesting about five times more protein per hectare of land than they would if they were raising cows for dairy.”

“That efficiency could come in handy in the case of a global catastrophe or during projected global food shortages. Research published in May by ALLFED, the Alliance to Feed the Earth in Disasters, found that leaf protein concentrate, which includes rubisco, could meet global protein requirements, even in an extreme nuclear winter scenario, because green leaves are relatively easy to grow quickly all over the world.”

     The company Leaft, based in New Zealand and recently expanding to the U.S., makes ready-to-drink performance fuel shots made of rubisco. Each pouch of greenish sludge contains 18 grams of protein, nearly a third of human daily needs. Another company, Fudi Protein, based in Wisconsin, hopes to market its rubisco product as an alternative to egg whites, but is still fundraising. Plantible Foods, which has operations in Texas and California, makes rubisco out of duckweed, or lemna.  

     A paper published in May 2026 in Sustainable Production and Consumption explores the global potential for integrated biorefineries for producing leaf protein and sugar. 

     Potential refined products include leaf protein concentrate (LPC), lignocellulosic sugar, and/or single-cell protein (SCP). A schematic of an integrated biorefinery is shown below.

     According to the paper:

“…we focus on perennial legumes that are much easier to obtain at scale with a stable high yield per hectare, have better protein quality, and provide multiple harvests per year while requiring no nitrogen fertilizer thanks to their natural nitrogen fixation. The leafy biomass, such as red clover or alfalfa, investigated in this study, is harvested and promptly transported to a nearby biorefinery to ensure immediate biomass processing, thereby minimizing nutrient degradation and preventing undesirable biological or chemical interactions.”

     The paper is quite detailed and explores the ramp-up speed of the technology, financing and production economics, land use, energy use, its capacity for catastrophe response, and its ability to cut waste compared to other protein sources. The paper notes that about 30% of global grasslands could provide the growing realm for crops like alfalfa and clover, both legumes.

     According to Fudi’s website, the biomass from the alfalfa is all usable and is returned to farmers.

“After protein extraction, 100% of the remaining alfalfa biomass — fiber, chlorophyll, and micronutrients — is retained and utilized rather than discarded.”

     Leaft makes a rubisco protein isolate and a rubisco protein concentrate. Plantible grows its lemna on aqua farms and processes it quickly after harvest.

 

References:

 

What to know about Rubisco, the most abundant protein on Earth. Alana Semuels. Time. June 1, 2026. What to know about Rubisco, the most abundant protein on Earth

Global potential of integrated biorefineries for leaf protein and sugar: Producing sustainable food and preventing starvation in catastrophes. Juan B. García Martínez, Jeffray Behr, Thalles A. Andrade, Simon Blouin, João Costa, and David Denkenberger. Sustainable Production and Consumption. Volume 64, May 2026, Pages 247-265. Global potential of integrated biorefineries for leaf protein and sugar: Producing sustainable food and preventing starvation in catastrophes - ScienceDirect

Global amount of RuBisCO - most abundant protein on Earth. Bionumbers. Harvard University. Global amount of RuBisCO - most abundant prot - Biosphere - BNID 103827

Nature's most abundant protein. Now your all-in-1 protein solution. Fudi Protein. FUDI Protein Pure RuBisCO Protein from Regenerative Alfalfa

Plantible Foods. Website. Plantible Foods - Better farms, better foods

Leaft Foods. Website. Leaft Foods

RuBisCO, Wikipedia. RuBisCO - Wikipedia