Effect of hydro-thermodynamic processing (HTD) on the physicochemical, techno-functional, nutritional, and structural properties of protein isolates from defatted camelina meal

Defatted camelina meal (DCM) is a by-product from the oil extraction process, typically containing 10% to 15% residual oil and 40% crude protein, emerging as a promising protein source. However, there is limited research in developing sustainable protein extraction methods from DCM and in evaluating the techno-functional and nutritional properties of protein isolates. HTD is a novel processing technology in food science, which can result in simultaneous crushing, agitation, and dispersion effects on foods. Therefore, this study aims to employ HTD to improve protein extraction yield from DCM and enhance the techno-functional and nutritional properties of protein isolates from DCM. The underlying mechanism will be elucidated by evaluating changes in physicochemical and structural properties. Top of FormDCM suspensions at the 1:10 (w/v) water ratio have been processed with HTD for one hour at a temperature of 25 degrees Celsius and pressure 1.1 bar.  Proteins were extracted from both HTD-processed DCM and non-processed DCM (control) using the alkaline solubilization and acidic precipitation method. Techno-functional properties of both protein isolates were determined such as water solubility, foaming property, and emulsifying capacity. The water solubility of the processed sample was significantly improved compared to the control at pHs of 8.0, 10.0, and 12.0. For example, the water solubility of the processed sample increased twofold compared to the control at pH 8.0. Nutritional properties were evaluated by the determination of amino acid composition, in-vitro protein digestibility, and anti-nutritional factors. To explore the underlying chemistry, we further analyzed the physicochemical properties (i.e., surface hydrophobicity, disulfide bond, particle size, zeta potential, and molecular weight) and structural properties (i.e., secondary structure, tertiary structure, and microstructure analyses) of protein isolates. This study provided a theoretical basis for the application of HTD technology in exploring DCM as a promising protein alternative source.

Keywords: Defatted camelina meal; Hydro-thermodynamic processing, Physicochemical characterization; Techno-functionality; Nutritional properties