Effect of Ultrasound Treatment on the Physicochemical, Nutraceutical, and Functional Properties of Lupine Flour

This study aimed to convert sweet and bitter lupine protein isolates to nano-emulsions and to develop products with the nano-emulsion and examine the stability; develop emulsification with ultrasonication; develop and characterize food protein-stabilized nanoemulsions; and to modify lupine protein properties with pH shifting and ultrasonication. The antioxidant activity of sweet and bitter isolates was decreased in the nano-particle sized samples when compared to non-nano particle-sized samples, as well as the inhibitory activity of both angiotensin-converting enzyme and alpha-amylase, while it increased in sweet and bitter lupine isolates. For both types of lupine, water holding capacity was increased, and foaming stability of nano treatment was increased in protein isolate samples. In lupine, albumins and three globulins fractions, namely, β-conglutin, α-conglutin, and γ-conglutin, were characterized as the main storage proteins. No clear differences were observed between nano and non-nano samples regarding albumins and three globulins fractions. The results of microstructure characterization showed that sonication leads to distortion/breakage of protein particles shape, which results in smaller proteins that can be used as a top-down approach for the formation of nano-sized protein particles. In this regard, sonication can be considered as a heterogeneous approach that may lead to de-aggregation, breaking of protein particles, and distortion of their shape.