Physical and aqueous approaches to produce protein from new pennycress varieties with enhanced properties

Abstract: Pennycress (Thlaspi arvense L.) is a winter oilseed crop that also functions as cover crop and a source of oil for biofuel and novel proteins. New yellow-seeded pennycress specialty varieties, named covercress, were recently developed via conventional breeding and gene editing, but their protein’s chemical and functional traits are still unknown. This work evaluated two covercress lines, Y1126 and TT8, for protein extraction and functionality, as well as the combination of cold pressing, alcohol defatting and saline extraction to produce protein isolates that would align better with clean labeling. Seeds were first cold pressed in a tubular radial expeller then defatted with anhydrous ethanol (60°C) until residual oil content was around 0.5%. Protein was extracted from the defatted meal using the saline-based method for wild-type pennycress (WTP; 0.1 M NaCl, 1: 10 w/v, 50°C, 2 h). Y1126 and TT8 press cakes contained 40-60% more albumin and globulin that did WTP press cake. TT8 protein recovery (40%) was double that of Y1126 and its extract had greater purity (87 versus 70% protein). Y1126 protein extract showed a nearly constant 68-70% solubility from pH 2-10. TT8 protein extract was more soluble in acidic pH (87-90% solubility) than Y1126, but its solubility was markedly reduced (to 55%) at pH >5.5. Y1126 showed greater foaming capacity than did TT8 (146-150 mL versus 134-138 mL), but TT8 foams were more stable (77-95% remaining foam after 15 min). TT8’s emulsifying properties (EAI 141-236 m²/g protein and ESI 15-26 min) were superior to those of Y1126. While both protein extracts did not form a gel, the other functional properties were generally superior to those of WTP protein. This work demonstrated the enhanced functionality of Y1126 and TT8 proteins and that the selection of seed source for protein recovery depends on the functionality required in the target product.