Preparation, de-colorization, and characterization of protein isolate from silflower (Silphium integrifolium Michx), an emerging perennial crop with food application potentials

Authors: Teng, Zi; Singh, Mukti; KENAR, JAMES - Retired ARS Employee; Liu, Sean

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2026
Publication Date: 2/10/2026
Citation: Teng, Z., Singh, M., Kenar, J.A., Liu, S.X. 2026. Preparation, de-colorization, and characterization of protein isolate from silflower (Silphium integrifolium Michx), an emerging perennial crop with food application potentials. Food Chemistry. https://doi.org/10.1016/j.foodchem.2026.148361.
DOI: https://doi.org/10.1016/j.foodchem.2026.148361

Interpretive Summary: Silflower, also known as perennial sunflower, is a drought-tolerant plant native to central United States. It can be grown during the fallow period of typical crop rotations to produce nutritious seed meal and forage for livestock, and requires less seeding and tillage effort than annual crops. Silflower seeds contain high-quality proteins like those found in sunflower seeds. However, the protein obtained with conventional methods has a dark color that is not acceptable in many food applications. To enable use of silflower protein in a broad range of food products, USDA-ARS scientists in Peoria, Illinois isolated a high-purity, light-colored protein powder from silflower seeds for the first time. The product has similar nutritional composition and physical properties to those of sunflower and soy proteins, making it suitable for use as a food ingredient in many existing food formulations such as snacks and protein shakes. These results will advance efforts to develop silflower as a high-value crop that provides American farmers with additional options and new economic opportunities.

Technical Abstract: Silflower, the perennial sunflower from North American prairies, presents multiple agronomic benefits fostering interest in domestication. Silflower seeds contain ~368 g/kg proteins, but the undesirable color of extracted proteins arising from protein/phenolic interactions limits their food applications. Hereby, we present the first investigation on the preparation, de-colorization, and characterization of silflower protein isolate (SiPI). Extracting at pH 9.5 recovered 52% of proteins from seeds but conferred SiPI a dark color accompanying total phenolic content of 3.28 mg/g gallic acid equivalent. Extraction at pH 6.0 with NaCl and optionally absorbent resins reduced phenolic content by up to 68% and increased brightness by up to 32%. SiPI contains ~59% ß-secondary structures and comprises subunits analogous to sunflower 11S and 2S proteins. Thermal denaturation and decomposition commence at (89–104) and (251–255) °C, respectively, depending on extraction procedure. This study paves the way for practical applications of SiPI and comprehensive utilization of silflower plants.