Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 5, 2008
Publication Date: February 20, 2009
Citation: Hojilla-Evangelista, M.P., Evangelista, R.L. 2009. Functional Properties of Protein from Lesquerella Fendleri Seed and Press Cake from Oil Processing. Industrial Crops and Products. 29(1):466-472. Interpretive Summary: Lesquerella is a crop that is native to North America and Mexico and is being developed as a domestic alternative to imported castor oil. Only one species, Lesquerella fendleri, is being domesticated for this purpose. Lesquerella oil contains three hydroxy fatty acids that are similar in structure to ricinoleic acid, the main fatty acid in castor oil. Lesquerella oil may replace castor oil for use in high-performance lubricants, paints, plastics, pharmaceuticals and cosmetics. Successful commercial production of Lesquerella oil will also generate protein-rich meals as co-products because the seed contains 22% crude protein. However, aside from its amino acid composition, little else is currently known about the properties of Lesquerella protein. Our study is the first to determine the functional properties of Lesquerella seed protein, describe how protein functionality was affected by oil processing conditions, and identify the possible uses of the seed and meal. We found that Lesquerella seed protein was most soluble (more than 60%) at very acidic and highly alkaline media. The protein was least soluble (25%) at neutral and lightly acidic pH (5.5-7). We also determined that Lesquerella protein had noteworthy functional properties (foaming and emulsifying properties and water-holding capacity) at neutral and alkaline pH, which strongly suggested that Lesquerella protein may be used in a variety of food and non-food applications. We noted that Lesquerella press cake had significantly reduced protein solubilities and functional properties at the pH levels tested. We attributed these results to the detrimental effects of heating during the cooking and screw-pressing stages of oil processing. The impaired functional properties of the Lesquerella press cake protein will likely limits its usefulness in food-based systems; however, the press cake protein may still find use in industrial applications such as glues. Our pioneering study on the functional properties of protein in Lesquerella seed and press cake from oil processing provides critical basic data that could be used by other academic and industry researchers to define the conditions for optimal extraction and recovery of Lesquerella proteins, as well as, identify and develop new uses for the protein products, thus improving the value of Lesquerella as an alternative oilseed crop.
Technical Abstract: This investigation determined the functional properties of protein in Lesquerella fendleri seed and in press cake from oil processing. Lesquerella seeds were cooked at 82 deg C (180 deg F) for 120 minutes in the seed conditioner, and then screw-pressed to extract the oil. Unprocessed ground, defatted Lesquerella seeds and press cakes were analyzed for proximate composition and protein functional properties. Protein from unprocessed Lesquerella seed showed the greatest solubility (less than 60%) at pH 2 and 10 and was least soluble (25%) at pH 5.5-7. Unprocessed Lesquerella protein also had high surface hydrophobicity index (S0), as well as, excellent foaming capacity and stability, emulsifying properties, and water-holding capacity (WHC) at pH 7. Protein solubility profile of the press cake showed up to 50% reduction in soluble proteins at nearly all pH levels, indicating heat denaturation during cooking and screw-pressing. Foaming capacity of the press cake protein decreased slightly, but foam stability was completely lost. Press cake protein also had markedly reduced values for S0, emulsifying properties and WHC, further confirming Lesquerella protein's sensitivity to heat treatment.