Tannins (commonly referred to as tannic acid) are water-soluble polyphenols that are present in many plant foods. They have been reported to be responsible for decreases in feed intake, growth rate, feed efficiency, net metabolizable energy, and protein digestibility in experimental animals.
Tannins are astringent, bitter plant polyphenols that either bind and precipitate or shrink proteins. They are composed of a very diverse group of oligomers and polymers.
They can have a large influence on the nutritive value of many foods eaten by humans and feedstuff eaten by animals. Tannins are common in fruits (grapes, persimmon, blueberry, etc.), in tea, in chocolate, in legume forages (trefoil, etc.), in legume trees (Acacia spp., Sesbania spp., etc.), in grasses (sorghum, corn, etc.).
Because tannins bind with other proteins, including those in human saliva, they create a characteristic astringent, mouth-coating sensation in the mouth.
Their primary role in nature is to make unripe fruits and seeds unpalatable, thus dissuading animals from eating them.
Tannins are a class of compounds in tea, especially black tea, which tend to have a bitter flavor and astringent properties. Tea high in tannins can be described as tannic.
Tannins in food
