Astringency and bitterness

Assessment of taste is achieved by sensory analysis, from very simple experiments such as triangular tests aiming at determining detection thresholds to complex descriptive analysis approaches. A method referred to as time-intensity that consists in recording continuously the intensity of a given sensation over time under standardized conditions has been applied to study flavonoid bitterness and astringency properties. 

Lea, A.G.H., Bitterness and astringency the procyanidins of fermented apple ciders. In Bitterness in Foods and Beverages. Developments in Eood Science 25 (ed. R.L. Rouseff), Elsevier, Amsterdam, 1990, p. 123. 

Gacon, K., Peleg, H., and Noble, A.C., Bitterness and astringency of flavan-3-ol monomers, dimers and trimers. Food Qual. Prefer. 7, 343, 1996. 

Brossaud, F., Cheynier, V., and Noble, A., Bitterness and astringency of grape and wine polyphenols. Aust. J. Grape Wine Res. 7, 33, 2001. 

Noble, A.C., Factors influencing perception of bitterness and astringency in foods and beverages, in Polyphenols 98. XVIXe Journees Internationales Groupe Polyphenols, INRA Editions, France, 1998,... 

The Folin-Ciocalteau (FC) procedure is one of the standard procedures in wine analysis, as well as in tea analysis (Wiseman et al., 2001). One drawback in interpretation is that different classes of phenolics have varying taste attributes, and tests for chemical astringency based on precipitation of proteins have been recently developed (Adams et al., 1999). In addition, if the food product contains sugar, it can mask the bitterness and astringency, as observed in ripe fresh fruit, sweetened chocolates, and tea. 

Proanthocyanidins are polymeric flavonoid compounds composed of flavan-3-ol subunits (unitii.3), and are responsible for bitterness and astringency in some foods and beverages. This unit describes methods for extracting and purifying proanthocyanidins, and for determining their subunit composition by HPLC. Based upon HPLC results, the average degree of polymerization and the conversion yield for purified proanthocyanidins can be determined. 

Proanthocyanidins are polymeric flavonoid compounds composed of flavan-3-ol subunits (Fig. II. 4.1), and are widely distributed in the plant kingdom, including plants that are important as a source of food (Santos-Buelga and Scalbert, 2000). They impart bitter and astringent properties. In addition, these compounds may have potential health effects (Santos-Buelga and Scalbert, 2000). 

Phenolic compounds are important components of many fruits, vegetables, and beverages, to which they contribute to flavor, color, and sensory properties such as bitterness and astringency. Recent interest in functional foods and the medicinal use of phenolic compounds have also stimulated interest in their chromatographic separation. 

JS Bonvehi, FV Coll. Evaluation of bitterness and astringency of polyphenolic compounds in cocoa powder. Food Chem 60 365-370, 1997. 

Extraction of a portion of whey proteins, peptides, and amino acids Suitable for extraction of caseins and peptides from young cheeses. Not as effect as water Extraction of bitter and astringent peptides... 

Harwalkar, V. R. and Elliott, J. A. (1971). Isolation of bitter and astringent fractions from Cheddar cheese. J. Dairy Sci. 54, 8-11. 

Haslam, E. (1998a). Taste, bitterness and astringency. In E. Haslam (Ed.), Praticalpolyphenolics from structure to molecular recognition and physiological action (pp. 178-225). Cambridge University Press. 

Noble, A. (1990). Bitterness and astringency in wine. In R. Rousseff (Ed.), Bitterness in Foods and Beverages (pp. 145-158). Amsterdam Elsevier. 

Red wines are characterized by bitterness and astringency, whereas white wines occasionally are bitter but seldom are astringent. In wine, both attributes are primarily elicited by the flavonoid polyphenolic compounds, which have been reviewed extensively elsewhere (i- i). In this chapter, attention will be focused on the most recent investigations of factors which influence perception of bitterness and astringency. 

Table I. Maximum Intensity (MAX) andTotal Duration (TOT) of Bitterness and Astringency of Flavan-3-ol monomers, dimers and trimers (n= 18 judges x 2 reps) (19)...

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