Effect of extraction routes on protein content, solubility and molecular weight distribution of Crambe abyssinica protein concentrates and thermally processed films thereof

[Display omitted] •The protein separation method determines properties of the films from concentrates.•Films from precipitates were stronger than those from lyophilized solutions.•Protein separation method influenced solubility of hot pressed protein concentrates.•Protein content and molecular weight distribution are influenced by separation method.•Precipitation of proteins resulted in high protein levels and aggregation on heating. To understand if and how extraction conditions influence properties of molded protein films, Crambe abyssinica protein concentrates were produced from deoiled seed meal under various extraction conditions. Properties of the resulting hot compression molded films were evaluated through the molecular weight distribution, protein polymerization behavior and tensile tests. Precipitated protein concentrates demonstrated higher protein content and a pronounced shift to higher molecular weight distributions and reduced solubility on heating, indicating increased protein polymerization compared to those from lyophilized supernatants. Thermally processed films from isoelectrically precipitated protein concentrates show a high resistance to extraction with a combination of reducing agent and denaturant, indicating the presence of non-disulfide covalent cross linking. Also, tensile strength was higher in concentrates from precipitated proteins compared to those from supernatants. The protein concentrates resulting in thermally processed films with a high protein content, the highest levels of protein-protein interaction and high tensile strength were based on alkaline extraction and isoelectric precipitation. Therefore, a combination of alkali extraction and isoelectric precipitation is recommended to produce protein concentrates for molded film production.