Old Man Saltbush powder: a high-protein, natural salt substitute for wheat-based food products
Research from RMIT University has characterised the physicochemical properties of Old Man Saltbush (Atriplex nummularia) powder, demonstrating protein quality comparable to soy and pea protein, more than double the protein content of wheat flour, and efficacy as a natural salt substitute — positioning it as a nutrient-dense functional ingredient for reformulated staple foods.
Samiddhi Gunathilake and Dr Mahsa Majzoobi at RMIT’s Food Research and Innovation Centre. © Michael Quin, RMIT University
Old Man Saltbush (Atriplex nummularia), a drought-tolerant native Australian shrub long used as stock fodder and a traditional food source for Indigenous Australians, has attracted scientific attention as a candidate functional food ingredient. A peer-reviewed study published in Food and Bioprocess Technology by food scientists at RMIT University, Melbourne, presents the first detailed physicochemical characterisation of saltbush powder and evaluates its impact on the nutritional and functional quality of wheat flour noodles.
Protein quality and amino acid profile
Central to the study’s findings is the protein quality of saltbush powder, which was found to nearly match the ideal amino acid requirements for human nutrition as defined by established reference patterns. Study first author and RMIT PhD candidate Samiddhi Gunathilake stated: “It is notably high in protein for a plant-based source, matching or outperforming other sources such as soy, pea protein and rice protein, underscoring its potential as a high-quality plant-derived protein option.”
Of particular nutritional significance is saltbush’s lysine content. Wheat-based products are typically deficient in this essential amino acid, yet saltbush powder was shown to contain substantial levels. Study lead Dr Mahsa Majzoobi noted: “While legumes are traditionally valued for their essential amino acids – particularly lysine and tryptophan – saltbush was shown to be a strong alternative source with its high protein content and substantial levels of essential amino acids, notably lysine, which wheat products typically lack. Blending wheat with saltbush powder therefore offers a strategy for developing products with a more complete protein profile.”
Fibre, mineral content, and functional properties
Beyond protein, saltbush powder demonstrated a broad nutritional profile. The ingredient was found to be rich in calcium, iron, phosphorus, zinc, and sodium. Its fibre content proved especially notable: when incorporated into wheat flour noodles, the saltbush formulation contained eight times the dietary fibre of standard wheat pasta. The researchers calculated that a single serving of wheat pasta with saltbush powder added provided close to half the recommended daily protein intake for an adult.
The higher fat content of saltbush powder, whilst potentially a formulation consideration, was identified as contributing to enhanced texture and mouthfeel in certain food applications. The ingredient’s green pigmentation was also noted as lending visual appeal to finished products, an attribute of relevance in consumer-facing product development.
Natural salt reduction in noodle applications
To evaluate practical application, the research team incorporated ground saltbush powder into wheat flour noodles. The addition significantly improved the nutritional profile of the pasta whilst also functioning as a natural salt substitute — a finding with direct relevance to food manufacturers seeking to reduce sodium content in staple products without compromising sensory characteristics.
Dr Majzoobi summarised the compositional advantage: “Our analysis showed saltbush powder contained more than double the protein content of wheat pasta and was eight times higher in dietary fibre. This meant, for example, that one serving of wheat pasta with saltbush powder added provided almost half the recommended daily protein intake for an adult.” She added that “these compositional differences highlight saltbush powder as a nutrient-dense ingredient that can significantly enrich wheat-based products both nutritionally and functionally.”
Next steps: scale-up, consumer studies, and supply chain
The RMIT team acknowledges that the current results, whilst scientifically compelling, require longer-term validation. Dr Majzoobi indicated that gut health and nutritional benefits must be confirmed through extended studies, and that consumer acceptance, large-scale processing performance, and supply-chain consistency of saltbush powder all require systematic investigation.
The next research phase will broaden the application scope to include breads, snacks, and plant-based protein foods, alongside larger sensory and consumer studies. The group also plans closer collaboration with growers and industry partners to address sustainable sourcing, processing optimisation, and scalability. As Dr Majzoobi stated: “Ultimately, our goal is to support the development of Australian-grown, climate-resilient ingredients that contribute to healthier and more sustainable food systems.”
Given Australia’s warm climate and the shrub’s established drought tolerance, saltbush presents a plausible climate-resilient crop for ingredient supply chains increasingly under pressure from environmental variability. The translation of these early-stage findings into commercially viable food formulations will, however, depend on the outcomes of the supply-chain and processing studies now planned by the RMIT team.
Reference
Gunathilake, S., & Majzoobi, M. (2025). Exploring the physicochemical properties of saltbush (Atriplex nummularia) powder as a novel sustainable food ingredient: Impact on wheat flour noodle quality. Food and Bioprocess Technology. https://doi.org/10.1007/s11947-025-04094-z
