Isolation and characterization of nettle (Urtica dioica L.) seed proteins: Conversion of underutilized by-products of the edible oil industry into food emulsifiers

This study aimed to upcycle a byproduct of the edible oil industry, cold-pressed nettle seed meal (CPNSM), into a plant-based emulsifier, thereby increasing the sustainability of the food system. The protein content of the nettle seed protein (NSP) powder was 48.3% with glutamic acid (16.6%), asparagine (10.7%), and arginine (9.7%) being the major amino acids. NSPs had a denaturation temperature of 66.6 °C and an isoelectric point of pH 4.3. They could be used as emulsifiers to form highly viscous coarse corn oil-in-water emulsions (10% oil, 4% NSP). Nevertheless, 10-fold diluted emulsions exhibited rapid creaming under different pH (2–9), salt (0–500 mM NaCl) and temperature (>40 °C) conditions, but they were relatively stable to aggregation. Our findings suggest that NSPs could be used as emulsifiers in highly viscous or gelled foods, like dressings, sauces, egg, cheese, or meat analogs. [Display omitted] •Nettle seed protein (NSP) powder was isolated from cold-pressed nettle seed meal.•NSPs remained in their native state due to the mild extraction conditions used.•NSPs could be used as a plant-based emulsifiers to form oil-in-water emulsions.•NSP-coated oil droplets were stable to coalescence, but not creaming (due to large size).•NSPs may be useful emulsifiers in plant-based foods, like dairy, egg, and meat analogs.