Key Findings
Flaxseed protein has been usually obtained by aqueous extraction of the seed meal involving solubilisation of proteins at high pH, followed by precipitation of the proteins at their isoelectric point. The high viscosity of mucilage reduces protein extraction efficiency and impedes the sedimentation of protein during separation. This study describes a new method to extract flaxseed protein concentrates (FPCs) using alkali isoelectric precipitation (A-FPC), enzymatic
(E-FPC) and enzyme-solvent assisted (ES-FPC) extractions. A description is provided as to methods to produce protein concentrate with low viscosity (E-FPC,ES-FPC). An evaluation of the physicochemical (zeta potential, conductivity, surface hydrophobicity, protein solubility) and emulsifying (emulsion capacity, droplet size, polydispersity, emulsifying activity, and stability) properties of extracted FPCs are described, and compared to pea protein. This study indicated that the incorporation of mucilage with proteins improves their emulsifying properties. Also different functional properties of the extracted protein concentrates could be achieved
using the different production methods, leading to potential use in food systems needing a specific functional property.
ABSTRACT
Physicochemical (zeta potential (ζ), conductivity, surface hydrophobicity (H0), protein solubility (PS)) and emulsifying (emulsion capacity (EC), droplet size, polydispersity (PDI), emulsifying activity (EAI), and stability (ESI) indexes) properties of alkali-(A-FPC), enzymatic-(E-FPC), and enzymatic-solvent-(ES-FPC) extracted protein concentrates from flaxseed meal (FM) were investigated and compared to commercial pea protein concentrate (PPC). The yield, composition, and properties of the protein concentrates were significantly influenced by the methods of extraction. All emulsions were similar in polydispersity with mono-modal droplet distribution and size of ⩽0.43μm that carried a net negative charge at neutral conditions (pH 7.0). A-FPC showed significantly higher H0 (66.14) than that of ES-FPC (52.63), and E-FPC (43.27) and was comparable to PPC (68.47). The highest solubility was found for E-FPC followed by A-FPC at neutral pH. A-FPC displayed significantly (p<0.05) the highest EC (87.91%), EAI (87.18m(2)/g) and ESI (12.51min) compared to the other protein concentrates.
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