Extraction of proteins from pennycress seeds and press cake

In order to more fully utilize pennycress, a potentially viable bio-diesel source, the proteinaceous components were extracted from pennycress seeds and press cake. The amino acid composition of the proteins present in pennycress was typical for proteins derived from plants, with glycine, glutamic acid and alanine being prevalent. Water, 0.5 M sodium chloride, 60% acetic acid, 0.1 M sodium hydroxide and ethanol were used in sequential order to remove the protein from pennycress seeds and press cake and determine the various soluble protein fractions. Extraction temperature was varied from 5 to 77 °C. The highest yield of material (35%) was obtained by extracting pennycress seeds with water at 77 °C. However, this material had only moderate levels of protein (25%) with the remainder being carbohydrates and oil (as determined by infrared spectroscopy). The use of 0.5 M sodium chloride to remove protein from press cake at 5 °C produced material with the highest protein content (83%), but extraction yield was 25%. When extractions were carried out at 77 °C, oil typically began to be a major impurity in the protein. Using bomb calorimetry, the material remaining after extraction was found to have some value as a fuel source.

► Pennycress seed and press cake have been subjected to classic solvent extraction to remove proteinaceous material.
► Both solvent and temperature conditions were varied where water gave the best protein yield but saline solution gave the best protein content.
► The proteinaceous material was a complex mix of individual proteins.
► Carbohydrates and oil were found to be the main impurities in the extracts.
► The material remaining after extraction would be a useful fuel.