Astringency and bitterness Astringency and Bitterness often go together in foods and may be confused, but they are actually quite different concepts. Bitterness is one of the basic food flavours, along with sweetness, saltiness and sourness.
Astringency on the other hand is a ‘mouth puckering’ effect which results from the action of some foods on the saliva in the mouth. Saliva in the mouth contains proteins which will react with tannins in foods. It has generally been accepted that astringency arises when lubricating salivary proteins are precipitated as a protein-tannin complex and the lubricating effect is lost making the mouth feel very dry. It is possible that the presence of this precipitate on the tongue and soft palate also contributes to the overall mouth-feel sensation of astringency.
• The difference is very pronounced in the production of beer: hops add bitterness to beer (because of isohumulone, iso-α-acids), whereas polyphenols add mainly astringency. In beer production, hops are added as a desirable ingredient during mashing while poylphenols are removed in the protein ‘break’ or scum which forms during kettle boiling. Sparging must be stopped before too many of the phenolics get washed from the malt into the wort.