Benchmarking of a microgel-reinforced hydrogel-based aqueous lubricant against commercial saliva substitutes.

Xerostomia, the subjective sensation of 'dry mouth' affecting at least 1 in 10 adults, predominantly elders, increases life-threatening infections, adversely impacting nutritional status and quality of life. A patented, microgel-reinforced hydrogel-based aqueous lubricant, prepared using either dairy or plant-based proteins, has been demonstrated to offer substantially enhanced lubricity comparable to real human saliva in in vitro experiments. Herein, we present the benchmarking of in vitro lubrication performance of this aqueous lubricant, both in its dairy and vegan formulation against a range of widely available and employed commercial saliva substitutes, latter classified based on their shear rheology into "liquids", "viscous liquids" and "gels", and also had varying extensional properties. Strikingly, the fabricated dairy-based aqueous lubricant offers up to 41-99% more effective boundary lubrication against liquids and viscous liquids, irrespective of topography of the tested dry mouth-mimicking tribological surfaces. Such high lubricity of the fabricated lubricants might be attributed to their limited real-time desorption (7%) from a dry-mouth mimicking hydrophobic surface unlike the tested commercial products including gels (23-58% desorption). This comprehensive benchmarking study therefore paves the way for employing these microgel-based aqueous lubricant formulations as a novel topical platform for dry mouth therapy.

Interfacial study of class II hydrophobin and its mixtures with milk proteins: relationship to bubble stability.

Class II hydrophobin (HFBII) is a very promising ingredient for improving food foam stability. Pure HFBII-stabilized bubbles exhibited exceptional stability to disproportionation (dissolution) but were not stable to bubble coalescence induced by a pressure drop. Bubbles stabilized by mixtures of HFBII + sodium caseinate (SC) or ß-lactoglobulin (BL) showed decreased shrinkage rates compared to pure SC or BL and improved the stability to pressure-drop-induced coalescence. Higher bubble stability was more closely correlated with higher surface shear viscosity than the surface dilatational elasticity of the mixed protein systems. Brewster angle microscopy observations and the high shear strength of adsorbed films, including HFBII, even in the presence of hydrophobic and hydrogen-bond-breaking agents, confirm that intermolecular attractive cross-links are unlikely to be the origin of the high strength of HFBII films. Possibly the HFBII molecules form a tightly interlocking monolayer of Janus-like particles at the air-water interface.

Preparation and characterization of the foam-stabilizing properties of cellulose-ethyl cellulose complexes for use in foods.

Surface active cellulose particles have been prepared for use as foam stabilizing agents in foods. Various sources of cellulose were broken down by combinations of milling, acid dissolution and treatment with cellulase. The most efficient and simple method was hammer and freezer milling of dry crystalline α-cellulose (Tencel). The resultant Tencel particles were made partially hydrophobic through precipitation of ethyl cellulose (EC) onto them in acetone-water dispersions. The optimum ratio of EC to cellulose and the optimum solids concentration (C(x)) at which to form the complexes were 1:1 and C(x) ≈ 1 wt %, respectively. Complexes combined at low concentrations (e.g., C(x) ≈ 0.1 wt %) with caseins or whey proteins gave significant improvements in stability of foams and bubbles to coalescence and disproportionation compared to either component alone. As such, the complexes could be a useful ingredient in improving the quality of various food foams.