Infrared spectroscopic analysis of structural features and interactions in olive oil-in-water emulsions stabilized with soy protein

Lipid and protein structural characteristics of olive oil-in-water emulsions formulated with various stabilizer systems were investigated using Fourier transform infrared spectroscopy (FT-IR). Proximate composition, water binding and textural properties were also evaluated in these emulsions. Two different olive oil-in-water emulsions were studied: E/SPI prepared with soy protein isolate as a stabilizing system, and E/SPI + SC + MTG prepared with a combination of soy protein isolate, sodium caseinate and microbial transglutaminase as a stabilizing system. Results showed that textural properties (P < 0.05) were dependent on the stabilizing system. E/SPI + SC + MTG emulsion presented greater (P < 0.05) lipid chain disorder, more lipid-protein interactions, and more (P < 0.05) α-helix and β-sheet structures. A relationship between textural and structural properties was also observed as a function of the stabilizing system employed in the formulation of emulsions. A more thorough understanding of this connection could help improve the development of food products with appropriate physical properties.