Polyphenols: factors influencing their sensory properties and their effects on food and beverage preferences

The chemical and physical basis for red wine astringency is reviewed. Models describing the physiological foundation of astringency are presented and compared. The phenolic and other red wine components that evoke astringency are described, together with their sensory properties and the factors that affect their perception. The paper also presents a detailed account of the chemical properties of saliva and the possible modes of interaction between these and red wine phenolics that lead to the necessary physical changes in saliva required to elicit astringency. Reasons for differences in astringency perception across oral sites and amongst individual tasters are also discussed. It is concluded that whilst great advances have been made in the field of red wine phenolic chemistry in recent years, a better understanding of the effect of wine polyphenol‐salivary protein interaction on the rheological properties of saliva is required in order to gain a comprehensive understanding of red wine astringency.

Red wine astringency: a review

Os compostos fenolicos tem sido muito estudados devido a sua influencia na qualidade dos alimentos. Englobam uma gama enorme de substâncias, entre elas os acidos fenolicos, os quais, por sua constituicao quimica, possuem propriedades antioxidantes. Assim, a presente revisao procura reunir diversos estudos que avaliaram o potencial antioxidante dos acidos fenolicos na conservacao de alimentos lipidicos. Alem disso, sao reunidos tambem estudos sobre a acao antioxidante destes compostos no sistema biologico atraves da neutralizacao dos radicais livres gerados no organismo, que estao associados a diversas doencas como câncer e doencas cardiovasculares.

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Ácidos fenólicos como antioxidantes

Astringency plays an important role in the sensory experience of many foods and beverages, ranging from wine to nuts. Given the recent trend toward fortifying consumables with astringent compounds and the evidence regarding the health benefits of some astringents, the mechanisms and perceptual characteristics of astringency warrant further discussion and investigation. This paper reviews the current state of the literature, including consideration of new methods for describing and measuring astringency, and provides an overview of research concerned with elucidating the physical, physiological, and psychological factors that underlie and mediate perception of this sensation.

Astringency: mechanisms and perception.

Effect of pH, ethanol and acidity on astringency and bitterness of grape seed tannin oligomers in model wine solution

Astringency of aqueous solutions of phenolic compounds (grape seed tannins, tannic acid, catechin and gallic acid) increased upon addition of citric acid, whereas the astringency of alum was reduced. Astringency of alum was decreased equivalently by addition of equi-sour levels of lactic acid, citric acid or hydrochloric acid. The difference between alum and the phenolic compounds is speculated to result from chemical modifications affecting binding of the astringents with oral proteins rather than cognitive differences. Chelation of the aluminum ion in alum by acids reduces its availability for interacting with salivary proteins or epithelial proteins. In contrast, the increased astringency produced upon acidification of phenolic compounds is speculated to result from the pH driven increase in the affinity of the phenols for binding with proteins. These results suggest that alum cannot be used interchangeably with phenolic astringents in psychophysical studies.

Keith K. Bodine

Papers

The Influence of Acid on Astringency of Alum and Phenolic Compounds