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Astringency
Last modified at 2/2/2021 2:46 PM by Maren Johnson
Page Content Astringency is a sensory attribute that is described as a drying-out,
roughening, and puckery sensation felt in the mouth. Foods that are
often astringent include red wine, green and black teas, soy-based
foods, and certain fruits, especially when they’re not yet ripe. In
these foods, astringency is caused by the polyphenolic compounds they contain. Polyphenols are the most common cause of astringency in foods, though acids, metal salts such as alum , and alcohols are known to also cause astringency 1.
Sensory assessment of astringency
Astringency tends to be a difficult sensory attribute to assess
because it takes over 15 seconds to fully develop, and it builds in
intensity and becomes increasingly difficult to clear from the mouth
over repeated exposures 2,3.
A few approaches can be employed to overcome these issues: one
suggested approach is the use of statistics to unearth “true” ratings
without the carryover artifact, but this does nothing to reduce the
cumulative effects of the sensation that can lead to taster fatigue 4.
A second option is to delay subsequent tasting of astringent samples
until the oral environment has returned to a baseline state, although
the strength of the sample and the number of sample repetitions will
impact the interstimulus period needed for this to occur. A third
option is to use a palate cleanser between samples. Several cleansers
have been identified for their ability to alleviate astringency
including various viscous polysaccharides and gums (e.g., pectin or
carboxymethylcelluslose), oils, and also crackers 5,6,7,8;
however, there is recent evidence suggesting that palate cleansers
capable of reducing astringency may be masking the sensation in
subsequent tastings 9.
The cause of astringency
The majority of studies on astringency support the notion that astringency is primarily a tactile sensation rather than a taste 6.
The mechanism of astringency is not fully understood, although it is
known that polyphenols bind and precipitate a class of salivary proteins
called the proline-rich proteins (PRPs) 10. One theory is that the precipitation of PRPs from saliva reduces its ability to lubricate, and this loss of lubricity is perceived as an increase in oral friction 11. A second theory proposes that the sensation is caused by a direct effect of astringents on the oral epithelium and that PRPs
play a protective role and prevent astringency by binding the
astringent compounds before they can interact with the oral mucosa 12.
Both theories predict that people with high salivary flow rates and
protein/PRP concentrations will report lower ratings of astringency.
Several studies support this prediction 12,13,14,15.
References
1 Green, B.G. 1993. Oral astringency: a tactile component of flavor. Acta Psychol 84(1):119-25.
2
Guinard, J.X., Pangborn, R.M., Lewis, M.J. 1986. The time-course of
astringency in wine upon repeated ingestion. American Journal of Enology
& Viticulture 37(3):184-9.
3 Lyman,
B.J., Green, B.G. 1990. Oral astringency: effects of repeated exposure
and interactions with sweeteners. Chem Senses 15(2):151-64.
4
Arnold, G. 1983. A tasting procedure for assessing bitterness and
astringency. In: Anonymous Sensory Quality in Foods and Beverages:
Definition, Measurement and Control. American ed ed. Chichester, West
Sussex; Deerfield Beach, Fla.: E. Horwood Ltd; Verlag Chemie
International. P109—114.
5
Brannan, G.D., Setser, C.S., Kemp, K.E. 2001. Effectiveness of rinses in
alleviating bitterness and astringency residuals in model solutions. J
Sens Stud 16(3):261-75.
6
Breslin, P.A.S., Gilmore, M.M., Beauchamp, G.K., Green, B.G. 1993.
Psychophysical evidence that oral astringency is a tactile sensation.
Chem Senses 18(4):405-17.
7
Colonna, A.E., Adams, D.O., Noble, A.C. 2004. Comparison of procedures
for reducing astringency carry-over effects in evaluation of red wines.
Australian Journal of Grape & Wine Research 10(1):26-31.
8 Ross,
C.F., Hinken, C.,Weller, K. 2007. Efficacy of palate cleansers for
reduction of astringency carryover during repeated ingestions of red
wine. J Sens Stud 22(3):293-312.
9 Lee,
C.A., Vickers, Z. M. 2010. Discrimination among astringent samples is
affected by choice of palate cleanser. Food Quality & Preference
21(1):93-99.
10
Baxter, N.J., Lilley, T.H., Haslam, E., Williamson, M.P. 1997. Multiple
interactions between polyphenols and a salivary proline-rich protein
repeat result in complexation and precipitation. Biochemistry (NY)
36(18):5566-77.
11
Clifford, M.N. 1997. Astringency. Proceedings of the Phytochemical
Society of Europe 41(Phytochemistry of Fruit and Vegetables):87-107.
12
Horne, J., Hayes, J., Lawless, H.T. 2002. Turbidity as a measure of
salivary protein reactions with astringent substances. Chem Senses
27(7):653-9.
13
Fischer, U., Boulton, R.B., Noble, A.C. 1994. Physiological factors
contributing to the variability of sensory assessments: relationship
between salivary flow rate and temporal perception of gustatory stimuli.
Food Quality & Preference 5(1, 2):55-64.
14 Imm,
B., Lawless, H.T. 1996. Relationships between salivary responses and
astringency, bitterness and sourness responses to aluminum ammonium
sulfate. Chem Senses 21(5):618.
15
Kallithraka, S., Bakker, J., Clifford, M.N., Vallis, L. 2001.
Correlations between saliva protein composition and some T-I parameters
of astringency. Food Quality & Preference 12(2):145-52.
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