ARS | Publication request: Extraction of proteins from pennycress seeds and press cake

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 5, 2012
Publication Date: May 15, 2012
Citation: Selling, G.W., Hojillaevangelist, M.P., Evangelista, R.L., Isbell, T., Price, N.P., Doll, K.M. 2013. Extraction of proteins from pennycress seeds and press cake. Industrial Crops and Products. 41(1):113-119.

Interpretive Summary: Pennycress is a winter annual plant that can be found throughout temperate America and is generally considered as being a weed. However, given its ability to grow during the winter months, it can be planted and harvested during a time period so as to not disrupt existing farm production. Pennycress seed has been shown to be a potential source for biodiesel as it has higher oil content (~36%) than soy beans. In order to fully obtain the value from this crop, additional high value materials are needed for the co-products remaining after oil removal. This material cannot be used as animal feed, due to the presence of compounds that cause reduced growth and improper organ function. In order to derive higher value from these co-products, research must be performed to determine what is present in the co-products. The research performed here demonstrates techniques to remove protein from the pennycress co-products and provides initial characterization of these proteins. This research will benefit the biodiesel industry by developing routes to deliver potentially valuable co-products and thereby improve the economics of this industry.

Technical Abstract: In order to more fully utilize pennycress, a potentially viable bio-diesel source, the proteinaceous components were extracted from pennycress seed 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 seed and press cake and determine the various soluble protein fractions. Extraction temperature was varied from 5 to 77°C. The highest yield of material (36%) was obtained by extracting pennycress seed 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.