Relative astringency

Porter, L.J. and Woodruffe, J., Haemanalysis the relative astringency of proanthocyanidin polymers. Phytochemistry 23, 1255, 1984. 

Bate-Smith, E.C., Haemanalysis of tannins the concept of relative astringency. Phytochemistry 12, 907, 1973. 

Hatano T, Kagawa H, Yasuhara T, Okuda T. Two new flavonoids and other constituents in licorice root their relative astringency and radical scavenging effects. Chemical Pharmaceulical Bulletin. 1988 36(6) 2090-2097. 

Hatano, T., H. Kagawa, T. Yasuhara, and T. Okuda Two New Flavonoids and Other Constituents in Licorice Root Their Relative Astringency and Radical Scavenging Effects. Chem. Pharm. Bull. (Japan), 36, 2090 (1988). 

The ability of tannins to precipitate water-soluble proteins is the main activity by which various naturally occurring polyphenols are defined as tannins. Several methods for measurement of tannins based on these activities have been developed (Bate-Smith 1973 Porter and Woodruffe 1984 Hagerman 1989). Methods for the assay of relative astringency (RA) and relative affinity to methylene blue (RMB) have been used frequently in pharmacological studies for the measurement of the tannin content of plant extracts (Okuda et al. 1985). 

Okuda T, Mori K, Hatano T (1985) Relationship of the structures of tannins to the binding activities with hemoglobin and methylene blue. Chem Pharm Bull 33 1424-1433 Ozawa T, Lilley TH, Haslam E (1987) Polyphenol interactions astringency and the loss of astringency in ripening fruit. Phytochemistry 26 2937-2942 Porter LJ, Woodruffe J (1984) Haemanalysis the relative astringency of proanthocyanidin polymers. Phytochemistry 23 1255-1256... 

Because of the presence of unoxidized catechins, green tea beverage is yellow-green in color and more astringent than black tea. While many of the components of black-tea aroma are represented in green tea, their relative proportions differ. 

With Guyton de Morveau, Lavoisier devised the system of chemical terms still used today. For the first time, the names of chemical substances described their constituents and proportions astringent Mars saffron became iron oxide, and philosophic wool became zinc oxide. Many contemporaries called Lavoisier s new chemistry The French Science. Today Lavoisier is regarded as the equal of Isaac Newton in physics, Charles Darwin in evolution, or Albert Einstein in relativity. 

In winter or in cold places, cold, bitter, sour and astringent herbs should be prescribed in a relatively low dose. This precaution relates to herbs that clear heat, cool blood and drain downward. In humid places, herbs that transform dampness, activate the Qi movement and promote digestion should be used in relatively large doses because the herbs need extra strength to overcome the dampness. 

Zinc is present in a number of pharmaceuticals, the most important of which is life-sustaining insulin. Many topical preparations contain zinc as the oxide, sulfate, or stearate as an astringent or antipruritic. Some foot powders contain the antifungicidal zinc undecenoate, and zinc pyrithione is used in antidandruff shampoos. After dissolving them in acid, the topical products can be easily analyzed by either atomic emission or atomic absorption spectroscopy (49), since they contain a relatively high concentration of zinc. However, atomic absorption is approximately four orders of magnitude more sensitive than atomic emission for the determination of zinc (Table 2) and offers superior precision for the analysis of injectable insulin (50), where zinc concentrations can be as low as 4 ppm (39). 

The relatively little-polymerized catechins and procyanidins (dimers, trimers, etc.) are the least reactive with proteins. The solution tasted more acid than astringent. 

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