Extensional and shear rheology of okra polysaccharides in the presence of artificial saliva

Abstract

Extensional and shear viscosities were studied for mixtures comprising artificial saliva and okra mucilage, the latter acting as a model thick-liquid food. These experiments aimed to obtain information on the flow-behavior information of the systems, underpinning the texture sensation of foods as perceived by dysphagic and xerostomic populations. Mixing okra mucilage with artificial saliva dramatically increases the shear viscosity of artificial saliva throughout the studied ranges of concentrations and deformation rates. Particle tracking does not suggest direct interactions between the components of artificial saliva and of okra mucilage. The rheology of the okra polymer (OP)–artificial saliva (AS) mixture is dominated by its extensional viscosity: Trouton ratios are in the order of tens to hundreds, while they decrease with increasing okra-mucilage concentration; this highlighs the dominance of the extensional rheology and the increasing importance of the shear mechanics with increasing okra content. The relaxation times and extensional moduli are also reported for the systems under study. Extensional and shear flows are of equal importance concerning the elastic behavior.

Nutrient density and oral processing properties of common commercial complementary porridge samples used in southern Africa: Effect on energy and protein intakes among children aged 6–24 months

“…Extensional deformation occurs when a stress is applied perpendicularly to the surface of the deformation (Lv, Chen, & Holmes, 2017), as in the up‐down (munching) oral processing method. Extensional flow may cause much higher deformations in colloidal systems in comparison with shear deformation (Yuan, Ritzoulis, & Chen, 2018). Furthermore, Lv et al (2017) have found that humans have a greater discriminatory capacity in perceiving extensional compared to shear viscosity, even though the mechanisms are not understudied (Yuan et al, 2018).…”

“…Extensional flow may cause much higher deformations in colloidal systems in comparison with shear deformation (Yuan, Ritzoulis, & Chen, 2018). Furthermore, Lv et al (2017) have found that humans have a greater discriminatory capacity in perceiving extensional compared to shear viscosity, even though the mechanisms are not understudied (Yuan et al, 2018).…”

Nature‐Derived Okra Gel as Strong Hemostatic Bioadhesive in Human Blood, Liver, and Heart Trauma of Rabbits and Dogs

“…[63] The mucilage of the okra is composed of up to 70% polysaccharides. [64,65] The okra gel is rich in acidic polysaccharides, [66] including galactose, rhamnose, and galacturonic acid, and their partially acetylated form. [67] However, okra gel as a hemostatic bioadhesive has never been reported.…”

Instrumental characteristics from extensional rheology and tribology of polysaccharide solutions

“…In many studies on extensional rheology, although synthetic polymers were used as a test specimen in most cases in the past, studies on food polymers increase recently using a capillary breakup extensional rheometer (CaBER). These include casein and starch (Chan et al, 2007), guar gum (GG; Duxenneuner, Fischer, Windhab, & Cooper‐White, 2008; Torres, Hallmark, & Wilson, 2014), xanthan gum and carboxymethyl cellulose (CMC) (Choi, Mitchell, Gaddipati, Hill, & Wolf, 2014), and okra viscous extraction (Yuan, Ritzoulis, & Chen, 2018). Usefulness of extensional viscosity has been validated for evaluating mechanical or rheological properties of dysphagia thickeners (Hadde & Chen, 2019; Nishinari, Turcanu, Nakauma, & Fang, 2019; Waqas, Wiklund, Altskär, Ekberg, & Stading, 2017).…”