Emulsifying properties of quinoa protein fibrillar aggregates and their influence on quinoa protein emulsion gel formation.

Fibrillization is a potential approach to improving functionality of seed storage proteins. Herein, the solubility, morphology, wettability, interfacial adsorption and emulsifying properties of quinoa protein fibrillar aggregates were compared with those of quinoa protein isolate (QPI). Effect of fibrillar aggregates on the formation of heat-induced QPI emulsion gels was investigated in the presence 0 or 100 mM NaCl. The results showed that fibrillization enhanced the relative solubility of QPI by ∼10 %, and reduced the contact angle from 130.5° to 83.4°. Both QPI and fibrillar aggregates exhibited outstanding emulsifying capacity and emulsion stability, preventing flocculation/coalescence. The interfacial protein concentration of fibrillar aggregate-stabilized emulsions was higher than that of QPI-stabilized emulsions, ranging from 16.3 to 33.4 vs. 12.4 to 29.2 mg/m at emulsifier concentrations of 0.5-3 % w/w. The self-standing emulsion gels were formed by heating 10 % w/w QPI emulsions with a storage modulus of 1886 Pa and a fracture stress of 582 Pa. Fibrillar aggregates acted as active fillers in QPI emulsions gels (8 % w/w QPI + 2 % w/w fibrillar aggregates) with a storage modulus of 2566 Pa and a fracture stress of 741 Pa. However, the addition of 100 mM NaCl destructed the gel network, leading to a reduction of gel strength.