Mimicking the Mouth in a Tribometer: Immobilizing a Lubricious Salivary Mucin for Frictional Measurements of Astringency Effects in Beverages and Foodstuffs
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2026-01-31
Publication Type
Journal Article
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yes
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Abstract
Astringency is a property of food and beverages that results largely from a friction-enhancing effect in the mouth. It can be conveniently assessed by tribological measurements, which have typically been carried out by investigating the effect of the astringent on the lubricating properties of whole-mouth saliva (WMS). Saliva is notoriously variable as a reagent, however, differing in its properties from person to person, day to day, and changing its behavior rapidly after removal from the mouth. We describe a far more convenient, reproducible, and potentially useful alternative to the use of WMS for ex vivo determination of the friction-enhancing effects of an astringent substance. Key to this development is the use of a nitrene-generating adhesion promoter to immobilize a crucial lubricating mucin, MUC5B, onto the tribopair-in this case silicone rubber (PDMS) and glass. Upon sliding in saline solution, this mucin-modified tribopair exhibits friction coefficients in the range of 0.002-0.006. Addition of 1 wt% potassium alum solution (a known astringent) leads to an order-of-magnitude increase in friction coefficient, while addition of samples of greater relevance to the food and beverage industry (grapeskin extract, red wine) shows comparable effects. Interestingly, the astringents' effect on the MUC5B-modified surfaces appears to be essentially reversible upon washing with saline solution and continued sliding, suggesting that the effects of astringents in the mouth are not necessarily associated with removal of the MUC5B from the oral mucosa.
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published
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Volume
74 (1)
Pages / Article No.
16
Publisher
Springer
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Subject
Astringency; Saliva; Wine; Oral lubrication; Mucin; MUC5B