A Tribological Model for Chocolate in the Mouth: General Implications for Slurry-Lubricated Hard/Soft Sliding Counterfaces

Lee, Sang M.; Heuberger, Manfred; Rousset, Philippe; Spencer, Nicholas D.

doi:10.1023/b:tril.0000009735.06341.32

Cited by 69 publications

(52 citation statements)

References 24 publications

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“…26 In other words, only a very small amount of oil is sufficient for lowering the friction. Given the fact that there is an inverse relation between fat perception and friction, [1][2][3][4][5][6] these findings contradict the sensory findings that fat content very clearly has an effect on fat perception and therefore on friction. 4,[27][28][29] Deformability of emulsion droplets is also expected to influence emulsion lubrication.…”

Section: Discussioncontrasting

confidence: 55%

“…However, various authors suggested that rheological behavior alone cannot explain mouth-feel but that a relation between in-mouth friction and fat-related mouthfeel can. [1][2][3][4][5] Recently, we demonstrated an inverse relation between perception of fat and in-mouth friction sensed between tongue and palate. 6 In addition, we showed that food oil-in-water (o/w) emulsions, which are sensitive toward coalescence, give rise to a lower orally perceived and measured friction and, probably as a consequence, have an enhanced fat perception.…”

Section: Introductionmentioning

confidence: 99%

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Tribology of o/w Emulsions Under Mouth-like Conditions: Determinants of Friction

et al. 2007

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Fat-perception is thought to be related to a complex interplay between fat-associated flavor release and mouth-feel. Friction sensed between the tongue and the palate seems to play a prominent role: in previous work, we have shown that emulsions that are more sensitive toward coalescence give rise to a lowering of the orally perceived and experimentally measured friction and, probably as a consequence, to an enhanced fat-perception. In this paper, we study in detail the factors determining friction of protein-stabilized emulsions using a novel mouth-mimicking tribometer and model surfaces consisting of PDMS modified in various ways (hydrophobicity, deformability, roughness). We show that unlike in many technological applications where lubrication is essentially hydrodynamic, for physiologically relevant loads, the modified PDMS is boundary and/or mixed lubricated, which is like in-mouth lubrication. We find that an increased sensitivity of the emulsions toward coalescence results in a lower friction, confirming previous results obtained with pig's tongue. Surface-induced coalescence (or spreading of emulsion droplets) seems to be very important in this, surface hydrophobicity being the dominant trigger. Viscosity of the dispersed phase does not have such a strong influence on both the measured friction and the oral perceived friction. We do find a strong influence of the presence of bulk proteins and saliva on friction. Finally, hardly any dependence of measured friction on fat content of the emulsion was observed, indicating that only a small amount of fat is needed to alter the friction.

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Section: Discussioncontrasting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Tribology of o/w Emulsions Under Mouth-like Conditions: Determinants of Friction

et al. 2007

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“…It is widely considered that as the film in the tongue-palate interface is sheared and thins, it is the tribological rather than rheology mechanism which dominates [1,[7][8][9]. Chocolate as a tribological material and the effect of oral processing on friction have proved difficult to study, and very few papers have been published [7][8][9]. Typically, molten chocolate is introduced into a sliding contact and friction coefficient measured over a range or speed or load values.…”

Section: Introductionmentioning

confidence: 99%

Friction Measurements with Molten Chocolate

Masen

Cann

2017

Tribol Lett

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A novel test is reported which allows the measurement of the friction of molten chocolate in a model tongue-palate rubbing contact. Friction was measured over a rubbing period of 150 s for a range of commercial samples with different cocoa content (85-5% w/w). Most of the friction curves had a characteristic pattern: initially a rapid increase occurs as the highviscosity chocolate melt is sheared in the contact region followed by friction drop as the film breaks down. The exceptions were the very high (85%) and very low (~ 5%) cocoa content samples which gave fairly constant friction traces over the test time. Differences were observed in the initial maximum and final friction coefficients depending on chocolate composition. Generally, the initial maximum friction increased with increasing cocoa content. At the end of the test, the rubbed films on the lower slide were examined by optical microscopy and infrared micro-reflection spectroscopy. In the rubbed track, the chocolate structure was severely degraded and predominately composed of lipid droplets, which was confirmed by the IR spectra. The new test provides a method to distinguish between the friction behaviour of different chocolate formulations in a rubbing low-pressure contact. It also allows us to identify changes in the degraded chocolate film that can be linked to the friction profile. Further development of the test method is required to improve simulation of the tongue-palate contact including the effect of saliva and this will be the next stage of the research.

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“…Drip-coating of PDMS pin alone was observed not as effective in the lubricity as drip-coating of PDMS disk alone (Figure 1(b)). In fact, this is a general trend for unsymmetrical tribopairs [8]. As pin in tribometer functions as slider, it is under a tribological stress, whereas disk experiences tribostress only periodically.…”

Section: Discussionmentioning

confidence: 99%

Self-restoring polymer brushes under tribological stress and the biomedical applications

et al. 2016

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For biological and mechanical systems involving moving parts, surface slipperiness is often a critical attribute for their optimal functions. Surface grafting with hydrophilic polymers is a powerful means to render materials slippery in aqueous environment. In "inverted grafting-to approach", the hydrophilic polymer chains of amphiphilic diblock copolymers dispersed within a poly(dimethylsiloxane) (PDMS) network are selectively segregated upon exposure to aqueous solution. This allows formation of extremely stable brush-like polymer layers. Tribological application of inverted grafting-to approach was successfully demonstrated with PDMS-blockpoly(acrylic acid) (PDMS-b-PAA) dispersed within thin PDMS films on PDMS blocks by showing friction coefficients (µ) of ca 10 -2 to 10 -3 , depending on the load, pH and buffer salinity in the absence of other external re-supply of PAA chains. Further manipulations of the thin PDMS film incorporating PDMS-b-PAA to optimize the tribological properties are presented. Lastly, first trials to employ PAA-grafted PDMS surface to generate in-vitro mucosae model are also presented and discussed.

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A Tribological Model for Chocolate in the Mouth: General Implications for Slurry-Lubricated Hard/Soft Sliding Counterfaces

Cited by 69 publications

References 24 publications

Tribology of o/w Emulsions Under Mouth-like Conditions: Determinants of Friction

Tribology of o/w Emulsions Under Mouth-like Conditions: Determinants of Friction

Friction Measurements with Molten Chocolate

Self-restoring polymer brushes under tribological stress and the biomedical applications

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