RMIT study uses ultrasound to extract protein from cauliflower leaf waste

Researchers at RMIT University have developed a method for extracting protein from discarded cauliflower leaves using high-power ultrasound, opening up a potential new use for one of the vegetable industry's most common waste streams.

• RMIT researchers used ultrasound-assisted extraction to recover protein from cauliflower leaves sourced from a commercial farm in western Melbourne.
• The study found that high-power ultrasound increased dry matter yield and improved protein recovery compared with conventional processing approaches.
• Researchers said the resulting leaf protein concentrate could have future applications in food products and animal feed.

The study examined how ultrasound technology could help recover valuable nutrients from cauliflower leaves, which are often discarded during processing despite containing protein and dietary fiber.

According to the researchers, the process uses high-frequency sound waves to break down plant cell walls, making it easier to release and recover proteins from the leaf material. The team found that applying ultrasound not only improved protein recovery but also increased dry matter yield.

The research also showed that different processing conditions influenced the characteristics of the resulting protein concentrate, including its particle size, color, solubility and structural properties.

Lead researcher Professor Asgar Farahnaky from RMIT's School of Science said the project focused on finding practical ways to recover value from agricultural byproducts already present in the food system.

The team used cauliflower leaves supplied by a commercial farm in western Melbourne and tested multiple processing approaches to determine how much protein could be recovered from the material.

“Ultrasound uses high-frequency sound waves to disrupt plant cell walls and help release protein from the leaves,” Farahnaky said.

“There is growing interest in alternative protein sources, and using existing waste streams could be a practical way to meet that demand without requiring additional production.”

Interest in alternative protein sources has continued to expand as food manufacturers seek new ingredients that can support sustainability goals while reducing pressure on conventional agricultural resources. Agricultural byproducts and food processing waste streams have increasingly attracted attention as potential sources of proteins, fibers and other functional ingredients.

Cauliflower leaves represent one such opportunity. While the leaves are produced in large quantities during harvesting and processing operations, they are typically discarded despite containing nutritional components that could potentially be recovered and utilized.

The researchers said the leaf protein concentrate generated through the extraction process could have future applications in both food and animal feed products, although additional work will be required before commercial deployment.

Farahnaky said the next phase of research would need to evaluate the technology beyond the laboratory environment.

He noted that further studies are required to test the process at pilot scale, assess its energy efficiency and examine sensory acceptability when incorporated into food products.

Study lead author and RMIT PhD candidate Kinjal Furia said the research was centered on improving the use of resources that are already available within existing food production systems.

“If we can use food waste streams more effectively, we can reduce environmental impacts while responding to growing interest in alternative protein sources,” Furia said.

The project was supported by cauliflower supplier Harvest Moon, which provided the plant material used in the research. The Leaf Protein Co. also contributed in-kind support to the study.

The findings were published in the journal Food and Bioprocess Technology under the title Sustainable leaf protein concentrate from cauliflower leaves via ultrasonication-assisted extraction and sieve filtration.

The study was authored by Kinjal A. Furia, Peter J. Torley, Mahsa Majzoobi and Asgar Farahnaky.