tannins Flashcards
this term was first applied by Seguin in 1796 to denote substances present in plant extracts which were able to combine with protein of animal hides, prevent their putrefaction and convert them into leather.
TANNINS
Tannins Is a substance which is detected qualitatively by ___
Tannin Test (Goldbeater’s Skin Test)
Tannins Is a substance which is determined quantitatively by its
absorption on standard hide powder.
T OR F
Only a few tannins are glycosides
FALSE
Tannins are source of fruit acids. Enumerate.
Glycolic
Lactic
Mandelic
Malic
Tartaric
Citric acid
T OR F
Tannins are found in mature fruits.
False
Tannins are found in specific plant parts. Enumerate.
Leaves
Fruits
Barks
Stems
Are Found in great quantities in dead or drying cells.
Occur in solution in cell sap, often in distinct vacuoles.
Tannins
a mixture of polyphenols and non-crystallizable compounds
Complex Substance
This may be hydrolyzed by acids or enzymes such as Tannase.
Hydrolysable Tannins
Hydrolysable Tannins may be hydrolyzed by acids or enzymes such as ____.
Tannase
They form several molecules of phenolic acids as Gallic acid and Hexahydroxy-diphenic acid which are united by ester linkages to a central glucose molecules.
Hydrolysable Tannins
What are hydrolysable tannins formerly known as?
Pyrogallol Tannins
dry distillation, Gallic acid and similar components are converted to
Pyrogallol
Hydrolysable Tannins When treated with acids/enzymes
Phenolic Acids (Gallic Acid, Ellagic Acid, Glucose)
Gallitannins
Gallic Acid
Ellagitannins
Hexahydroxy-diphenic acid units
Ferric Chloride (Hydrolysable Tannins)
Blue Color
Bromides (Hydrolysable Tannins)
No precipitate
Condensed Tannins (Proanthocyanidins, Polyflavonoid, Catechol-type, Pyrocatecollic-type tannins)
Non-Hydrolysable Tannins
Are not readily hydrolyzed to simpler molecules and they do not contain a sugar moiety.
Non-Hydrolysable Tannins
Are related to the Flavonoid pigments and have polymeric Flavan-3-ol structures.
Non-Hydrolysable Tannins
Catechins which also occur with the tannins and Flavan in the biosynthesis of the molecules.
Non-Hydrolysable Tannins
Non-Hydrolysable Tannins When treated with acids/enzymes
converted into red insoluble compounds known as Phlobaphenes