Based on pulse dry fractionation technology from protein-mill.com, dry fractionation maintains native protein functional properties because it separates protein bodies from starch and fibre using purely physical mechanical and aerodynamic forces, without harsh chemical, pH or thermal treatments that denature protein structure.
1. No extreme pH, no chemical solubilisation / precipitation
Wet protein extraction typically uses alkaline solubilisation followed by acid precipitation near the protein isoelectric point. Repeated pH swings disrupt hydrogen bonds, hydrophobic interactions and disulfide bonds inside globulin storage proteins (legumin and vicilin). Dry fractionation operates at the natural pH of the raw pulse seed. Proteins remain in their native folded conformation; no acid or base is added to unfold or precipitate protein molecules.
2. Minimal heat exposure during milling and classification
The whole dry fractionation process runs at near ambient temperature. While ultra-fine grinding generates minor frictional heat, properly designed milling and air classifier systems limit temperature rise and avoid thermal denaturation. Unlike thermal sterilisation, drying or spray-drying steps common in wet extraction, there is no sustained high heat that permanently unfolds protein tertiary and quaternary structures. Native globulin assemblies stay intact.
3. Separation is based on particle size and aerodynamic behaviour, not protein dissolution
In dry fractionation, protein bodies are physically liberated from cotyledon cell matrices by milling, but proteins never dissolve into an aqueous phase. Wet extraction forces protein molecules to dissolve and then re-aggregate during precipitation, which permanently alters particle morphology and functional behaviour. In the dry route, protein bodies remain as solid subcellular particles; their intrinsic molecular folding and surface properties are retained.
4. No denaturing washing or concentration steps
Wet processing includes multiple aqueous washing, membrane concentration and drying stages. These steps can induce protein-protein interactions, aggregation and surface modification. Dry fractionation skips all liquid-phase handling. Protein particles only interact with air, so there is no irreversible aggregation caused by solvent exchange, concentration gradients or dehydration stress.
5. Preservation of natural protein–minor component associations (controlled)
Native protein bodies naturally contain embedded minerals and phytic acid. Dry fractionation does not strip these native complexes. While phytic acid may reduce solubility, the native protein surface chemistry remains unchanged, preserving inherent emulsifying, water-binding, fat-binding and gelling capacity that depends on the original protein surface structure.
Dry fractionation does not guarantee zero functional change. Excessive milling can create localised frictional heating and surface damage to protein particles, which may slightly reduce functionality. Therefore, selective, low-energy milling is essential to protect native protein structures. When milling parameters are well controlled, dry-fractionated protein concentrates retain better native functionality than wet-extracted counterparts.
