Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/3/2006
Publication Date: 6/1/2006
Citation: Xu, J., Mohamed, A., Hojillaevangelist, M.P., Sessa, D.J. 2006. Viscoelastic properties of lupin proteins produced by ultrafiltration-diafiltration. Journal of the American Oil Chemists' Society. 83(6)553-558. Interpretive Summary: Lupin is an important legume plant. Its seeds contain high concentrations of proteins and oil. Due to its unique characteristics of containing high concentrations of proteins and oil, as well as being easy to grow and harvest, lupin could have more food and non-food applications. However, there is very little research with lupin and its proteins and oil, especially their physical properties and structure/function relationships, which restricted the usage of lupin in the U.S. This paper investigated viscoelastic properties for lupin proteins produced by ultrafiltration-diafiltration. We found that ultrafiltered-diafiltered (DUD) lupin proteins had some interesting property shifts among a range of concentration changes. The information that this work provided can be used by other researchers in the lupin field, and also can be used for further food and non-food application studies of lupin proteins.
Technical Abstract: The linear and non-linear rheological properties of defatted lupin proteins produced by ultrafiltration-diafiltration were investigated. Five concentrations ranging from 10% to 30% of the defatted ultrafiltered-diafiltered (DUD) lupin proteins were prepared. The viscoelastic properties strongly depended on concentrations. Below 12%, the DUD lupin proteins exhibited more fluid-like behavior. At 15%, lupin proteins became more viscoelastic, and above 20%, the viscoelastic solid-like properties became stronger. Below 12%, the high-frequency behaviors of moduli were proportional to omega 3/4, as expected for a semi-flexible coil. Above 20%, the high-frequency behaviors of moduli were proportional to omega 1/2, indicating a flexible coil. The non-linear steady shear rheological properties were also concentration dependent and showed shear-thinning behavior, which could be described by a power law constitutive model. The trend of the power law exponent shift is very consistent with the linear viscoelastic behavior change with the lupin protein concentration. These results suggest DUD lupin proteins undergo a structural change between 12% and 20%.