Chia (Salvia hispanica) protein fractions: characterization and emulsifying properties

A material with a high content of fibers and proteins is generated as a by-product of the chia oil extraction process. A strategy to add value to this by-product is to evaluate its possible use as a food ingredient. Thus, using a chia protein-rich fraction (CPRF) of chia seeds as starting material, albumins, globulins, glutelins, and prolamins fractions were obtained, characterized, and their emulsifying properties investigated. CPRF covers the essential amino acid requirements suggested by FAO; protein fractions only cover the requirements for Tre, Tyr and Val. Protein solubility profile for CPRF, globulins and prolamins was similar, with maximum solubility at pH 9. In contrast, glutelin and albumin fractions showed highest solubility at pH 5. Oil/Water (O/W) emulsions, using the chia protein fractions as emulsifying agent, were obtained at different pH (3, 5, 7, and 9) in their native and denatured state. The global stability and the destabilization kinetics of these systems were evaluated by their backscattering profiles. Additionally, the particle size distributions and their D4.3 diameter were determined. The emulsions destabilization occurred mainly by creaming process, with globulins as the fraction that led to most stable systems. Besides, high pH values improved the stability of emulsions prepared with globulins, glutelins, and the protein-rich fraction. The heat treatment application only slightly improved the emulsifying activity of the CPRF. These results indicate that chia protein fractions could be used as food ingredient to improve the amino acid content and the techno-functional properties of the functional foods.