Relating rheology and tribology of commercial dairy colloids to sensory perception

Abstract

ARTICLEThis journal is © The Royal Society of Chemistry 20xxJ. Name., 2013, 00, 1-3 | 1 This study aims to investigate the relationship between rheological and tribological properties of commercial full fat and fatfree/ low fat versions of liquid and soft solid colloidal systems (milk, yoghurt, soft cream cheese) with their sensory properties. Oscillatory measurements (strain, frequency), flow curves and tribological measurements (lubrication behaviour using Stribeck analysis) were conducted. Oral condition was mimicked using artificial saliva at 37 C. Discrimination test was conducted by 63 untrained consumers, followed by a qualitative questionnaire. Consumers significantly discriminated the fat-free/low fat from the full fat versions (p<0.01 -free samples. Flow behaviour of both versions of milk showed overlapping trends with no significant differences identified both in absence and presence of saliva (p>0.05). Full fat and fat free yoghurts had similar yielding behaviour and elastic modulus (G'), even in simulated oral conditions. However, in case of G low fat counterpart. Even in presence of artificial saliva, there was slight but significant difference in viscoelasticity between the cream cheese variants depending on fat content (p<0.05). Stribeck curve analyses showed that at lower entrainment velocities (1 100 mm/s), both full fat yoghurt and soft cream cheese exhibited a significantly lower traction coefficient when compared to fat-free/low fat versions (p<0.05), which might be attributed to the lubricating effect of the coalesced fat droplets. Surprisingly, whole and skim milks showed no significant difference in traction coefficients irrespective of the entrainment speeds (p>0.05). Results suggest that sensory distinction between fat-free and full fat versions, particularly in semi-solid systems could be better predicted by lubrication data as compared to bulk rheology. .

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

“…This agedependent increase in salivary viscosity was also further supported using elongational thread viscometer by Kazakov, Udod, Zinkovych, Fainerman, and Miller (2009). Currently oral tribology is emerging as a promising tool to quantify friction and lubrication of food-saliva mixtures in the oral mucosa using in vitro polymeric set up Laguna, Farrell, Bryant, Morina, & Sarkar, 2017;. Studies involving xerostomia patients have reported reduced sulfation of salivary mucins (both MUC1 and MUC2), which may affect the lubricating property of saliva (Chaudhury et al, 2016).…”

“…Currently oral tribology is emerging as a promising tool to quantify friction and lubrication of food‐saliva mixtures in the oral mucosa using in vitro polymeric set up (Laguna et al, ; Laguna, Farrell, Bryant, Morina, & Sarkar, ; Laguna & Sarkar, ). Studies involving xerostomia patients have reported reduced sulfation of salivary mucins (both MUC1 and MUC2), which may affect the lubricating property of saliva (Chaudhury et al, ).…”

Gellan gum: A new member in the dysphagia thickener family

“…Due to the complex composition of saliva (ions, mucin, enzyme) it is highly likely that some sensitive thickeners could alter their mechanical properties when in contact of saliva. Additionally, viscosity alone might not allow a thorough understanding of the mechanical properties of a food product undergoing oral processing [2,[24][25][26][27][28]. Therefore, studying the lubrication properties of these thickeners, via oral tribology measurements which is currently gaining momentum in oral processing research, is required to provide understanding on the interaction of these thickeners with oral surfaces and therefore, indirect insights on the stickiness or slipperiness of different thickeners.…”

“…The tribological properties of the different thickener samples were measured using a Mini Traction Machine 2 (MTM2, PCS instruments, London UK) following the method from [24].…”

Oral Lubrication Matters: Effects on Satiety

“…The smooth steel surfaces in this device, commonly used in engineering disciplines, were replaced by a polydimethylsiloxane (PDMS) ball and disc set-up at 37 °C to mimic the oral surfaces (surface roughness, Ra < 50 nm). 33,34 The rolling speed was reduced from 1000 to 1 mm/s at a load of 2N, using a slide-to-roll ratio (SRR) of 50 %, and the coefficient of friction in the mixed lubrication regime (50 mm/s) was measured in triplicate.…”