Plant Protein Extraction and Functional Characterization

Proteins derived from plant sources such as canola and rapeseed have gained significant attention for their nutritional value, sustainability and versatile functional properties in food systems. The extraction of these storage proteins typically involves defatting steps—via solvents or mechanical pressing—followed by aqueous or alkaline solubilisation to separate protein fractions from fibres, polyphenols and other anti-nutritional factors. Advances in extraction strategies including bleaching with hydrogen peroxide and the use of deep eutectic solvents have enhanced yield and purity while modulating protein conformation. Downstream fractionation techniques such as ultrafiltration and ethanol or resin adsorption further refine isolates, enabling tailored protein compositions enriched in cruciferin or napin. Functional characterisation encompasses assessment of solubility, water and oil absorption, foaming and emulsification. At interfaces, the molecular architecture of cruciferin and napin dictates dilatational and shear rheology, foam overrun and emulsion stability. Cruciferin typically imparts stiff, solid-like interfacial films that resist coalescence, while napin adsorbs rapidly to promote high foamability and initial emulsion formation. A detailed understanding of structure–function relationships under varying pH, ionic strength and processing conditions underpins the development of plant-based ingredients with bespoke techno-functional performance, fuelling innovations in sustainable food formulation and alternative biopolymer applications.

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Plant Protein Extraction and Functional Characterization publication trend

The graph below shows the total number of articles in plant protein extraction and functional characterization across all publications each year (not limited to Nature Index journals).

Technical terms

Cruciferin: A high-molecular-weight 11S storage protein abundant in rapeseed, forming β-sheet-rich, stiff interfacial films.

Napin: A small 2S storage protein from rapeseed, characterised by rapid adsorption and high initial foamability but lower film rigidity.

Emulsifying properties: The capacity of proteins to adsorb at oil–water interfaces and stabilise droplets against coalescence.

Foamability: The ability of proteins to generate gas-liquid foams, typically quantified by foam overrun and initial foam volume.

Dilatational rheology: The study of interfacial film response to changes in surface area, revealing film elasticity and strength under deformation.

References

1. Cruciferin versus napin – Air-water interface and foam stabilizing properties of rapeseed storage proteins. Food Hydrocolloids (2023).
2. Oil-water interface and emulsion stabilising properties of rapeseed proteins napin and cruciferin studied by nonlinear surface rheology. Journal of Colloid and Interface Science (2024).
3. Optimization of canola meal bleaching by hydrogen peroxide, protein extraction and characterization of their functional properties. Future Foods (2023).
4. Impact of alkaline and deep eutectic solvent extraction on rapeseed protein isolates characteristics and in vitro digestibility. Current Research in Food Science (2025).