Extraction, composition and functional properties of pennycress (Thlaspi arvense L.) press cake protein

Authors: Hojilla-Evangelista, Milagros - Mila; Selling, Gordon; Berhow, Mark; Evangelista, Roque

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2015
Publication Date: 6/15/2015
Publication URL: http://handle.nal.usda.gov/10113/62244
Citation: Hojilla-Evangelista, M.P., Selling, G.W., Berhow, M.A., Evangelista, R.L. 2015. Extraction, composition and functional properties of pennycress (Thlaspi arvense L.) press cake protein. Journal of the American Oil Chemists' Society. 92(6):905-914.

Interpretive Summary: Pennycress, although historically considered a weed, has now found potential value as a source of bio-diesel that will not compete with food production. For pennycress to develop into a new crop with high value, all parts of the seed must be utilized. In this research, we produced protein concentrates (70-86 % protein content) from pennycress press cake (that which remains after oil removal) by using two methods so that we may identify and develop novel uses for the protein. There is substantial protein in pennycress seed meal (about 27%) and press cake (about 35%). The press cake is anticipated to be the source of pennycress protein, which could become the major co-product of processing pennycress oil for biodiesel production. In the present work, we determined the composition, amino acid profiles, and functional properties (value in use) of the pennycress protein extracts recovered from the two methods. We noted that extraction method had significant effects on the purity and functional properties of the protein concentrate. We observed that pennycress protein isolated by one technique had higher purity (86%) and superior foaming properties. In contrast, protein isolated using a different method showed remarkably higher solubility and exceptional abilities as an emulsifier. We also found that the nutritional quality of pennycress press cake protein is equivalent to those of soybean, canola, or rapeseed protein concentrates and isolates. Our results showed that pennycress proteins produced by either extraction routes have nutritional and functional properties that are desirable for both food and non-food uses (e.g., whipped or foam products, emulsions, or as nutritional supplement in beverages). This information will have value to growers and companies interested in bio-diesel production or the production of new food sources.

Technical Abstract: This study compared two methods for extracting the protein in pennycress (Thlaspi arvense L.) press cake and determined the composition and functional properties of the protein products. Proteins in pennycress press cake were extracted by using the conventional alkali solubilization-acid precipitation (AP) method or saline-based (SE) procedure (0.1M NaCl at 50°C). Extraction method has major influence on purity and functional properties of press cake protein product. AP had lower protein yield (23%) but much higher purity (90% crude protein) compared with SE (45% yield, 67% crude protein). AP protein isolate had high foam capacity (120 mL), high foam stability (96% foam volume retention), high emulsion stability (24-35 min), and was resistant to heat denaturation (3% loss of solubility at pH 2 and pH 10). On the other hand, SE protein concentrate showed remarkably high solubility (>76%) between pH 2 and 10 and exceptional emulsifying activity (226-412 m2/g protein), but was more susceptible to heat denaturation at pH 7 and pH 10 (65-78 % loss of solubility). These results strongly demonstrate that higher-purity pennycress press cake protein can be produced by either saline extraction or acid precipitation and have functional properties that are desirable for non-food uses.