Mechanochemistry May Extract Edible Proteins from Marsh Grass

Researchers have demonstrated how mechanochemistry can be used to extract edible proteins from marsh mallow, a common weed species in England.

Bernardo Castro-Dominguez, co-lead researcher from Bath University in England, says: "What excites me is that we have shown that grass can be used to produce building blocks for food."

With a growing global population and changes in dietary consumption, there is a need to obtain edible proteins using alternative and sustainable methods. Previous studies have reported edible protein extraction from grasses, but Castro-Dominguez explains that "most traditional methods use very harsh solvents or chemicals to break down cell walls." While these methods are often effective, he notes that "when you subject vitamins and proteins to these harsh conditions, they tend to degrade." He emphasizes: "We want to have proteins that are in completely good condition for human consumption."

Now, Castro-Dominguez and colleagues have developed a sodium carbonate-assisted grinding technique to extract nutrient-rich protein fractions from marsh mallow. He explains: "Instead of chemically breaking it down, imagine a mortar and pestle grinding down the grass structure mechanically to break it apart and recover the good things inside the grass."

Benu Adhikari, a food engineering specialist from the University of Queensland in Australia, says Castro-Dominguez's team has done good work: "Along with proof, they proposed a gentler and better protein extraction technology."

Analysis of amino acids in the protein fractions revealed potential applications for different food products. For example, levels of glutamic acid, an amino acid associated with umami flavor, were elevated in samples. They also found that amino acid profiles were similar to soya or oat protein, suggesting these could be substituted without sacrificing their nutritional benefits.

Castro-Dominguez explained that examining the thermal stability of the fractions showed that the mechanochemical method left "the chains somewhat longer or in better condition compared to traditional alkaline extraction, which allows them to withstand higher temperatures and could facilitate their use in cooking processes."

Nevertheless, we still need some time before we can source our next meal using grasses found in the nearest field. Adhikari notes that "a lot of work needs to be done, particularly on safety aspects." He says it is "too early" to say how this work will impact sustainable food industries, but adds: "This is certainly beautiful and extraordinary work and deserves scientific recognition."

"Something we're working on right now is the techno-economics of the process. We're also trying to understand whether people would be willing to eat grass-based proteins or grass-based foods," says Castro-Dominguez. The team is now looking for ways to remove the distinctive color and aroma of grass to help with this. "We showed protein production here, but our juice smoothies also contain quite a lot of sugar. And these sugars could be used," adds Castro-Dominguez. "Actually, there are several steps that need to be taken forward for this, but that is where we are heading."