Functional and flavour properties of de-oiled flours and dry-enriched protein concentrates of lupin and soy

Abstract

Dry fractionation is low in energy and water use and thus a sustainable option to obtain protein-rich ingredients. Air-classification is used to remove starch from legumes, and electrostatic separation can be used to remove fibres from other starting materials like oilseeds. Flour from oil-rich crops needs to be de-oiled to facilitate dry fractionation, which involves the use of organic solvents or mechanical pressing and might affect the ingredient functionality. This research evaluated if the functionality of soy and lupin is affected by solvent de-oiling and electrostatic separation. Industrially toasted soy and lupin flour contained native protein, which was preserved upon electrostatic separation, de-oiling with hexane and de-oiling with acetone, but ethanol de-oiling resulted in protein denaturation. De-oiling with ethanol or hexane is preferred over de-oiling with acetone based on the flavour profile after de-oiling. The use of different solvents affected the solubility to a different extent and electrostatic separation resulted in a similar or higher solubility of the ingredients (22% - 49%), dependent on the solvent, crop and pH condition used. Overall, electrostatic separation resulted in protein-enriched ingredients (43%DM - 67%DM Nfactor=5.7) that show potential for application as stabilizers in emulsion-based systems like dressings or frozen foam-based systems like ice-cream.