Nutritional and Functional Potential of Rapeseed and Canola Proteins: Advances in Protein Extraction, Phenolic Removal, and Food Applications.

Abstract

Oilseeds, such as rapeseed and canola, are promising plant protein sources, containing approximately 35%-50% protein on a dry weight basis, comparable to soy (30%-55%) and pea (23%-30%). However, their application in foods is limited by anti-nutritional factors (ANFs), residual oils, and phenolic compounds, which impair solubility, digestibility, and functional performance. This review critically evaluates protein extraction and refining strategies from rapeseed and canola meals, emphasizing phenolic removal to enhance functionality. Conventional alkaline extraction followed by isoelectric precipitation often co-extracts phenolics and partially denatures proteins, whereas alternative approaches, including mild salt-assisted extraction, ethanol-assisted phenolic removal, ultrasonication, pulsed electric fields, enzyme-assisted extraction, green solvents, and ultrafiltration, improve protein yield (65%-94%), reduce total phenolics (50%-99%), and preserve native cruciferin and napin structures. Phenolic management enhances solubility (20%-80% pH 4-8), emulsifying activity (EAI 200-650 m²/g), emulsion stability (ESI 20-52 min), gel strength (G' 50-120 Pa at 10%-15% protein), and water and oil-holding capacities (WHC 3-6 g/g; OHC 5-7 mL/g). Mechanistically, phenolic removal decreases protein-polyphenol complexation, maintains quaternary structure, and increases molecular mobility, supporting heat-induced gelation and interfacial performance. These functional improvements enable applications in meat analogs, dairy alternatives, baked goods, protein-fortified beverages, and microencapsulated bioactive systems. Overall, effective phenolic removal enhances functionality and nutritional quality, positioning rapeseed and canola proteins as viable food-grade plant proteins. Their utilization promotes sustainable food systems, reduces reliance on animal proteins, and addresses malnutrition in resource-limited settings, while aligning with circular economy principles and United Nations Sustainable Development Goal 12.