Rheological Behavior of Food Emulsions Mixed with Saliva: Effect of Oil Content, Salivary Protein Content, and Saliva Type

Abstract

In this paper, we studied the effect of saliva on the rheological properties of β-lactoglobulin-and lysozyme-stabilized emulsions, prepared at pH=6.7 in relation to variation of emulsions-and saliva-related parameters. The effect of oil-volume fraction (2.5% w/w to 10% w/w), salivary protein concentration (0.1 to 0.8 mg ml −1 ), and the use of both stimulated and unstimulated saliva was investigated. Viscosity and storage modulus were measured before (η emul and G′ emul , respectively) and after addition of saliva (η mix and G′ mix ). To better estimate the changes due to saliva-induced flocculation of the emulsions, the ratios η mix /η emul , G′ mix /G′ emul were calculated. In addition, tan δ (=the ratio of the loss and storage moduli) was investigated to evaluate the viscoelastic behavior of the emulsion/saliva mixtures. Increasing the oil-volume fraction and salivary protein concentration resulted in an increase in η mix /η emul and G′ mix /G′ emul , while a decrease in tan δ of the emulsion/ saliva mixtures is occurring. When compared with unstimulated saliva, mixing β-lactoglobulin-stabilized emulsions with stimulated saliva led to a reduction in η mix / η emul and G′ mix /G′ emul , and an augment of tan δ at all measured deformations. In case of lysozyme-stabilized emulsions, the use of stimulated saliva increased G′ mix / G′ emul for +<3 when compared to unstimulated saliva. The effect of stimulated saliva on the η mix /η emul and tan δ in this mixture is similar to that of unstimulated saliva. These results indicate that the influence of stimulated saliva on the rheological parameters of emulsion/saliva mixtures largely depends on the type of emulsions. To conclude, our findings demonstrate that the rheological behavior of emulsions upon mixing with saliva is greatly affected by both saliva and emulsion properties.

Aging‐related changes in quantity and quality of saliva: Where do we stand in our understanding?

“…Saliva properties differ as a function of the collection method (Proctor, ; Stokes & Davies, ). Many studies demonstrated distinct results (e.g., rheology, tribology) when using stimulated versus unstimulated saliva (Prinz et al, ; Silletti et al, ). In addition, the difference of salivary stimulation is magnified in the elderly.…”

“…Stimulated saliva contains lower quantities of protein (e.g., glycosylated mucin) and has a lower viscosity than that of the unstimulated counterpart. Many studies demonstrated differences in rheological and tribological properties between these two types of saliva (Prinz, de Wijk, & Huntjens, 2007;Silletti, Vingerhoeds, van Aken, & Norde, 2008).…”

Isolation of Candida species in children and their biofilm-forming ability on nano-composite surfaces

“…The proteomic study revealed over 1050 diverse kinds of proteins in saliva. One of the constituents of the saliva, which is mucins consist of highly glycosylated particles (Silletti et al, 2008). More than a few protein organizations such as MUC5B networks increase the complexity of the saliva structures.…”

Acceptability and Digestibility of Emulsions in a Rat Model: Effects of Solid Fat Content and Lipid Type

“…The process of emulsion breakdown begins in the mouth where salivary mucins and shear between the tongue and palate cause extensive flocculation and coalescence [8]. In the stomach there is some enzymatic hydrolysis of the surface proteins which may lead to coalescence as well as possible flocculation induced by the change in pH [9].…”