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Grass half full

Grass half full

Grass and other plant biomass may represent an innovative new protein source for use in food and beverages.

With the world’s population expected to increase from eight billion in 2023 to ten billion by 2050, the demand for protein for human consumption is rising. Accordingly, there is a need to look towards alternative protein enterprises to improve the competitiveness of agri-ecological systems through the diversification of protein resources. This is a topical area of research and development to improve food security, sustainability and variety within the diet. Technological innovation in plant proteins can add value; however, research efforts are primarily concentrated on mainstream crops.

Extraction from ryegrass

A new trend focuses on extracting proteins from low-value plant biomass, explains Sara Pérez-Villa, a PhD student at Teagasc Moorepark’s Food Research Centre. “These types of plant biomass include forages such as clover or alfalfa and other green leaves, such as the side streams from other crops like quinoa, wasabi or tomato,” says Sara. “Green leaves contain high levels of the enzyme RuBisCO, which is involved in plant photosynthesis and is a protein source with good nutritional properties.”

However, they also contain high levels of cellulose, hemicellulose and lignin, which are indigestible to humans; therefore, they require an extraction process to obtain a digestible food protein-based ingredient. Using laboratory methods, the research team at Moorepark separated the soluble and digestible protein RuBisCO from lignocellulose (dry plant biomass). The importance of proteins in food systems relies on their nutritional value and food-structuring properties, Sara explains. “The study focused on the extraction of RuBisCO from perennial ryegrass (PRG) by two different approaches, thus tailoring the extraction yield and the functionality of the resulting protein in solution,” she says.

Regardless of the extraction procedure used, protein streams had a balanced amino acid profile, meeting FAO 2011 recommendations, meaning they could become an alternative source of protein for food applications with good nutritional value.

Green light for green leaves?

The research team found that it was possible to increase solubility or extraction yield depending on the method used. The extract containing less residual chloroplast material had greater solubility, up to 40% more, and superior emulsifying properties at non-acidic pH. The interfacial properties of the extracted grass protein were influenced by its isoelectric charge (pI) and also pH of the emulsion system. For instance, at pH 7, higher than the protein’s isoelectric point, the protein extract in which the chloroplast material was removed had similar emulsification properties to animal-based proteins.

The relative accessibility of plant biomass, and its potential for adaptability, is a promising sign for this research, concludes Sara. “What the study has shown is that protein extracts from green leaves, such as the perennial ryegrass used in this case, consisting mainly of RuBisCO, have potential application for use in formulations intended for human consumption.”  

This article was first published in TResearch Winter 2023. Read the latest TResearch articles here


Sara Pérez-Vila, PhD student, Teagasc Food Research Centre, Moorepark.
Laura G. Gómez-Mascaraque, Senior Research Officer, Teagasc Food Research Centre, Moorepark. laura.mascaraque@teagasc.ie
Sinead Fitzsimmons, U-Protein Project Manager, Teagasc Food Research Centre, Moorepark.
Mark Fenelon, Head of Food Programme, Teagasc Food Research Centre, Moorepark.