Effects of cold-pressing and seed cooking on functional properties of protein in pennycress (Thlaspi arvense L.) seed and press cakes

Authors: Hojilla-Evangelista, Milagros - Mila; Evangelista, Roque; Isbell, Terry; Selling, Gordon

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2012
Publication Date: 1/22/2013
Citation: Hojilla-Evangelista, M.P., Evangelista, R.L., Isbell, T., Selling, G.W. 2013. Effects of cold-pressing and seed cooking on functional properties of protein in pennycress (Thlaspi arvense L.) seed and press cakes. Industrial Crops and Products. 45(1):223-229.

Interpretive Summary: In this research, we determined the composition and functional properties of pennycress seed protein and how they are affected by oil extraction conditions, so that we can consequently design practical methods of extracting the protein on a larger scale, as well as identify and develop novel uses for the protein. Pennycress seed oil is being developed as alternative feedstock for biodiesel production. If this venture is successful, then the seed protein, which is present in notable amounts (about 27%), could become a major co-product of pennycress oil-based biodiesel industry. However, there is almost no information about pennycress seed protein and its uses are likewise unknown. In our present study, we evaluated the effects of oil processing conditions, such as cold-pressing (no heat) or cooking-then-pressing on the soluble protein classes in pennycress seed and press cakes and also on their other functional properties (solubility, foaming, emulsification, water-holding capacity). We found that the major proteins were the water-soluble and saline-soluble classes, which means that simple solvents would be effective in extracting and recovering protein from pennycress seed. We observed that cooking severely reduced the amounts of these major proteins in the press cake. We noted that the protein from our seed meal and press cakes had poor solubility in acidic media and were only moderately soluble at neutral and alkaline pH. Despite the limited solubility, both seed and press cake proteins had excellent foaming capacities, foam stabilities, and emulsifying properties that compared well with those of soybean and rapeseed protein. Our results showed that pennycress seed and press cake proteins are sensitive to heating but still has useful functional properties, such that the most promising opportunities for their utilization would be in pressurized foam or whipped products and emulsions (paints).

Technical Abstract: Current interest in pennycress (Thlaspi arvense L.) comes from its seed oil, which is being evaluated for biofuel production. The seed also has notable protein content (27% moisture-free, oil-free basis). The effects of oil processing conditions on functionality of pennycress seed proteins were determined to identify potential uses for the meal. Whole seeds were either simply cold-pressed or heated at 82°C with residence time of 50 min in the seed conditioner. Oil was extracted by screw-pressing. Composition and functional properties (solubility, foaming, emulsification, water-holding capacity) of extractable proteins in press cakes and unprocessed pennycress seed were determined and compared. Pennycress seed protein had predominantly albumins and globulins, no prolamins, and few glutelins. Cooking significantly reduced the amounts of albumins and globulins in the press cake. All samples showed the lowest solubility (10%) at pH 4 and only moderate solubility (35-45%) as pH increased. Both seed and press cake proteins had excellent foaming and emulsifying properties, but press cake proteins had higher water-holding capacities. These results showed that protein in pennycress seed and press cake from oil processing is sensitive to heating but still has useful functional properties.