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

• DOI: 10.1007/s11483-008-9089-0
• Publication Date: 2008-06-17T12:19:19Z
• Authors: Erika Silletti; Monique H. Vinger...; George A. van Aken; Willem Norde
• Keywords: HUMAN GLANDULAR SALIVAS; DEPLETION-FLOCCULATION; MICELLE-LIKE STRUCTURES; in-water emulsions; depletion-flocculation; micelle-like structures; ORAL BEHAVIOR; oral behavior; 03 medical and health sciences; 0302 clinical medicine; STABILIZED EMULSIONS; flocculation; sodium caseinate; lysozyme; human glandular salivas; emulsion; saliva; beta-lactoglobulin; TRANSMISSION ELECTRON-MICROSCOPY; transmission electron-microscopy; SODIUM CASEINATE; BETA-LACTOGLOBULIN; POLYSACCHARIDE; polysaccharide; rheology; IN-WATER EMULSIONS; stabilized emulsions

In this paper, we studied the effect of saliva on the rheological properties of beta-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 (eta(emul) and G'(emul), respectively) and after addition of saliva (eta(mix) and G'(mix)). To better estimate the changes due to saliva-induced flocculation of the emulsions, the ratios eta(mix)/eta(emul), G'(mix)/G'(emul) were calculated. In addition, tan delta (=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 eta(mix)/eta(emul) and G'(mix)/G'(emul), while a decrease in tan delta of the emulsion/saliva mixtures is occurring. When compared with unstimulated saliva, mixing beta-lactoglobulin-stabilized emulsions with stimulated saliva led to a reduction in eta(mix)/eta(emul) and G'(mix)/G'(emul), and an augment of tan delta at all measured deformations. In case of lysozyme-stabilized emulsions, the use of stimulated saliva increased G'(mix)/G'(emul) for gamma