Lupin: Prospective superfood or potential allergen?
Date of Award
Doctor of Philosophy
School of Science
Michelle L. Colgrave
James A. Broadbent
Thao T. Le
The demand for plant-based protein sources is on the rise. Lupins, important members of the legume family, are one of the richest natural sources of protein and fibre and can positively contribute to global food and nutritional security. Despite their strong potential, lupins remain under-utilised as a human food and are predominantly grown as green manure and livestock feed. One constraint to the widespread adoption of lupins in the food industry is allergenicity, which has led to its inclusion in the list of food allergens subjected to mandatory labelling in many countries.
The research presented herein focused on the study of proteins in lupin seeds, aiming to incentivise exploitation of this under-utilised legume by enhancing the available proteome-level knowledge and addressing the allergenicity challenges attributed to this legume. Firstly, the efficiency of four solvents (IPA-DTT, Tris-HCl, Urea and IPA→Urea) in extracting proteins from three narrow-leafed lupin genotypes (Tanjil, Unicrop and P27255) were evaluated through global discovery and quantitative proteomic approaches. The integration of complementary solvent systems enabled identification of 2,760 proteins from these genotypes. In addition, the proteome-wide relative quantitative analysis highlighted differences in the protein profiles of the wild and domesticated lupin genotypes and demonstrated the substantial influence of the protein extraction method on the proteome coverage and downstream biological interpretation of the data.
The diversity of the major lupin seed storage proteins, known as conglutins, were assessed across a panel of 46 genetically diverse narrow-leafed lupin genotypes. The differentiation and relative quantitation of the 16 conglutin sub-families, belonging to the four major α-, β-, γ-, and δ- families, was achieved by monitoring a set of maker peptides specific to each protein sub-family. Whilst this comparative evaluation determined distinct differences in the conglutin profiles of the lines under investigation, the major variability was observed for the β-, and δ-conglutin sub-families, wherein, the allergenic β-conglutin proteins were found at considerably lower levels in a subset of Australian and Polish domesticated varieties. These narrow-leafed lupin cultivars can serve as potential hypoallergenic varieties and be implemented in breeding programs for further enhancing the lupin grain as a human food ingredient.
Finally, a combination of discovery and targeted quantitative proteomic approaches were applied to examine the changes driven by solid-state fermentation (induced by the starter culture Rhizopus oligosporus) in the white lupin allergenic protein profiles. The comparative proteomics study of the allergen derived peptides across the pre-fermented and fermented samples revealed a significant decrease in the levels of ~94% of the monitored peptides as result of fermentation. This effect was more prominent across the β-conglutin peptides, for which a decrease > 50% was observed for ~70% of the monitored peptides. These observations suggest good efficiency of solid-state fermentation for the degradation of the allergenic proteins and development of innovative lupin-based food products with reduced allergenicity.
The findings of these proteomic studies contribute to advancing the proteome-level knowledge available for lupin seeds, thereby providing opportunities to now enhance lupin seed protein composition and stimulate the broader application of this grain legume as a food ingredient.
Access to this thesis has been embargoed until 3rd May 2024
Tahmasian, A. (2023). Lupin: Prospective superfood or potential allergen?. https://doi.org/10.25958/XMHZ-4177