Extraction and properties of proteins in covercress, new pennycress varieties developed as cover crop and alternative plant protein source

Authors: Hojilla-Evangelista, Milagros - Mila; Evangelista, Roque; Selling, Gordon; ULMASOV, TIM - Covercress, Inc

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2022
Publication Date: 12/29/2022
Citation: Hojilla-Evangelista, M.P., Evangelista, R.L., Selling, G.W., Ulmasov, T. 2023. Extraction and properties of proteins in covercress, new pennycress varieties developed as cover crop and alternative plant protein source. Journal of the American Oil Chemists' Society. 100(4):329-341. https://doi.org/10.1002/aocs.12675.
DOI: https://doi.org/10.1002/aocs.12675

Interpretive Summary: Pennycress is a new winter oilseed crop that can be grown in rotation with corn and soybeans in the Midwest, and also a source of oil and protein, thus providing additional revenue streams to farmers. New pennycress varieties were recently developed through conventional breeding techniques or gene editing to obtain specialty traits such as lower fiber and higher protein or oil contents. Little is still known about the properties of the proteins of these new varieties. In this research, we evaluated three new pennycress lines (B3, black-seeded, high fiber; Y1126 and TT8, both yellow-seeded, low fiber/high oil) for protein extractability, composition, functional properties (solubility, foaming, emulsification, water-holding capacity, and gelation), and overall suitability for the rapidly expanding plant-based protein market. We obtained the protein by using methods previously developed in our laboratory to produce high-purity protein extracts. We recovered more protein from the TT8 and Y1126 varieties than from the B3 sample (one-half versus one-third of available protein). We found that, while all three new varieties showed generally superior protein properties to those of field pennycress protein, the TT8 variety demonstrated the best performance with respect to protein extractability, purity (94% versus 71-75%) and functional properties. The TT8 protein had notably higher solubility in acidic media and improved foaming capacity/stability and gelation. This work produced protein products from new pennycress varieties with desirable properties as a novel plant-based protein that would be particularly useful for developing dairy substitutes (shakes, whipped toppings, cheese, yogurts, desserts), baked goods, or alternative meat products.

Technical Abstract: Pennycress (Thlaspi arvense L.) is a winter oilseed crop that also functions as cover crop, oil feedstock for biofuel, and novel plant-based protein. New pennycress specialty varieties were developed by conventional breeding techniques, but protein chemical and functional traits are still unknown. This research evaluated three new lines (black-seeded B3 and yellow-seeded TTG1/Y1126 and TT8) for protein extractability and functionality. Seeds were ground cryogenically and then hexane-defatted until residual oil content was 0.5-0.7% dry basis, db. Protein in defatted seed meals was extracted using saline method (1: 10 w/v, 0.1 M NaCl, 2 h, 50°C). TT8 and Y1126 had greater protein recoveries (ca. 50%) than those of B3 (36%) and wild-type pennycress (WTP, 40%). TT8 produced higher purity protein isolate (94.3%) than did Y1126 (75.0%) and B3 (71.3%). TT8 showed widely different protein band patterns from WTP, B3 and Y1126, reflecting varietal changes. The new varieties’ protein extracts were more soluble than WTP protein in acidic pH, with TT8 showing highest solubility (81-93%). TT8, Y 1126 and B3 foaming capacities (113-135 mL) were superior to those of WTP (101-107 mL). Emulsification properties (EAI 95-230 m2/g protein, ESI 13-24 min) were similar and increased with pH. B3, Y1126 and TT8 formed heat-induced gels at much lower concentration than did WTP (3% versus 6%) and their water-holding capacities (pH 7) were 2- to 5-fold greater. This work demonstrated that mutations in the TTG1 or TT8 gene in yellow-seeded lines resulted in improved protein recoveries and functionalities that are desirable in plant-based proteins.