Protein preparations from rapse processing waste: A review of the current status and development prospects of existing technologies

The demand for protein products is increasing due to the demographic growth of the world’s population. As an alternative to traditional sources of protein, waste from plant raw material processing is becoming increasingly popular. An important place in the global economy is occupied by oilseeds, in particular rapeseed, which production volumes are increasing in the Russian Federation every year. Rapeseed (Brassicaceae napus) is of great interest due to its high oil content (39.80–46.00%) and rich fatty acid composition, while cake and meal formed in the process of oil production are characterized by a significant content of crude protein (35.00–45.00%) and crude fiber (8.20–17.50%); however, they are used mainly as a feed additive. Recent studies on the processing of rapeseed waste indicate the value of this raw material as a source of dietary protein, which has a balanced amino acid profile and a high degree of digestibility (up to 85%). To obtain protein, rapeseed processing is envisaged: cleaning, grinding, cold pressing at a temperature of ≤ 40 °C, fat extraction with a solvent. At the next stages, the protein is extracted with 0.1–0.5 M NaCl at pH 5.3–12.0 and a temperature of 5–30 °C for 1 hour. The extracted protein is precipitated at the isoelectric point (pH 4.0) with HCl, separated from the mixture and neutralized. The result is a protein isolate with a protein content of 90.0–98.7%. It is possible to increase the quality and yield of the protein product due to the additional stage of processing the defatted cake with cellulolytic enzyme preparations. In this case, additional studies are required to determine the substrate specificity of commercial cellulase enzyme preparations and the optimal hydrolysis conditions. The parameters of extraction and precipitation of the protein in the case of using the stage of enzymatic lysis should also be specified.