Effect of fish gelatin and gum arabic interactions on concentrated emulsion large amplitude oscillatory shear behavior and tribological properties

Abstract

Concentrated emulsions stabilized by proteins, polysaccharides, or a combination are the basis for many food products such as mayonnaise and heavy cream. However, fundamental influences of protein–polysaccharide interactions on concentrated emulsion tribological properties and large deformation behavior are often poorly understood, leading to difficulties in targeted development of concentrated food emulsions with palatable textures and good stability. Thus, the objective of this study was to characterize the effects of fish gelatin (FG)–gum arabic (GA) complexation on the large amplitude oscillatory shear (LAOS) and tribological behaviors of concentrated emulsions. Concentrated emulsions (oil phase volume fraction = 0.7) were prepared using FG–GA mixtures at different aqueous phase pH (3.6, 5.0, and 9.0) and characterized by rheometry and tribometry. Samples prepared with FG–GA mixtures at higher pH showed lower critical strains, increased extent of nonlinear behavior under LAOS (higher G′3/G′1 and G″3/G″1 values), increased strain hardening and shear thinning under LAOS (G′L/G′M and η′L/η′M values further from unity, respectively), and higher friction coefficients. These results were attributed to reduced FG–GA electrostatic complexation as pH increased from 3.6 to 9.0. Complexes formed at lower pH induced higher droplet monodispersity, greater network extension, and smaller oil droplets, resulting in greater structural stability to deformation. These stability differences would likely contribute to differences in food textures and stability under food processing and storage conditions.