Preparation and properties of solution cast films from pennycress protein isolate

Authors: Selling, Gordon; Hojilla-Evangelista, Milagros - Mila; Hay, William; Utt, Kelly; Grose, Gary

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2017
Publication Date: 6/8/2018
Citation: Selling, G.W., Hojilla-Evangelista, M.P., Hay, W.T., Utt, K.D., Grose, G.D. 2018. Preparation and properties of solution cast films from pennycress protein isolate. Journal of the American Oil Chemists' Society. 95:1091-1103. http://dx.doi.org/10.1002/aocs.12034.
DOI: https://doi.org/10.1002/aocs.12034

Interpretive Summary: Pennycress is a potential crop which may grow over the winter and be a good source for biodiesel. As such it could provide an additional revenue stream for farmers and downstream converters. However, in order for growers and converters to be interested in this crop, all parts of the seed must be used. The research efforts reported here concern the protein fraction of the seed. An improved method was developed to extract the protein component from the seed on a large (10 pound) scale. The protein isolated was of high purity and after dissolving in formic acid, quality films were produced with good elongation and good resistance to water vapor and oxygen - suggesting that the films could be used in food packaging applications. The pennycress protein films are negatively impacted by high humidity and routes are being explored to provide water resistant films. This information will be beneficial to manufacturers involved in the production of biodiesel and all participants in the potential revenue stream.

Technical Abstract: This research evaluated a value-added use of pennycress protein by producing films and determining their properties. Pennycress (Thlaspi arvense L.) grows over the winter months, and is harvested in the spring. Pennycress seeds have high oil content and are a good candidate for biodiesel production. In order to extract the most value from pennycress, all parts of the seed must be utilized. An improved pilot-plant method for extracting protein from pennycress was developed providing a pennycress protein isolate (PPI) in high yield and purity (92% crude protein). Formic acid was found to be a good solvent for PPI and was used to produce transparent colored films. Glycerol (GLY) was found to be a good plasticizer for PPI, and films having between 10 and 30% GLY were produced. Higher GLY content resulted in films with an increase in elongation (up to 194%) but reduced tensile strength (TS) (from 21.8 to 3.2 MPa). With increasing relative humidity (RH), TS decreased and elongation increased. The glass transition temperature and heat deflection temperature for select PPI films were between 75–115 and 93–117'°C, respectively. The films had relatively low water vapor and oxygen permeability. The overall balance of properties suggests that PPI films may have value in film applications, especially in composites where exposure to moisture may be minimized.