BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

IV. PLANT ANATOMY

Secondary Plant Substances

Tannins

These are phenolic polymers used as mordants in dyeing and as tanning agents in the leather industry.

Tannins are subdivided into condensed and hydrolyzable tannins.

The latter are further divided into gallotannins and ellagitannins. Gallotannins are found in the leaves and leaf galls of Sicilian sumac. Upon Hydrolysis, gallotannin breaks down into glucose and gallic acid.

Ellagitannins yield insoluble ellagic acid during hydrolysis. They are found in pomegranate peel and the husks of unripe walnuts.

Condensed tannins do not undergo hydrolysis. They are polymers of catechins and leucoanthocyanins. Sources of condensed tannins include the bark of willow, pine, spruce, larch, acacia, horse chestnut, and oak. In medicine, they are valued for their astringent properties.

During black tea production, the enzymatic oxidation of catechins yields dimeric rather than polymeric Condensation products. These serve as typical dietary tannins.



Last update: 07/08/2026

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