Investigation of Tannin of Boplar's Bark (P.deltoides and P.euramerican)

The forest trees barks have compounds which the major part of that is tannin. Tannins are complex polyphenolic compounds with great structural diversity. Tannins have Bitter flavor and contractible effects. Tannins react with protein of skin. Therefore, they can be used in medicine and industry. The aims of this study are measurement of yield, phenolic compounds and tannins of poplar's bark (P.deltoides and P.euramerican). After collection of barks and drying, extraction was done according to TAPPI standard (T204 om-88) using acetone, ethanol and water solution and also we extracted materials of barks with NaoH solution (W/V 1:10) in temperature of 90˚C and in a period of one hour. Active phenolic compounds of extractive materials of tree barks were evaluated by Stiasny Number method. According to Hagerman 1998, condensed tannin was measured by using Column chromatography and Sephadex LH-20. Liquid solution of Fecl3 was used to determine Hydrolysable tannins. The extractive materials yield of populus deltoides and and populus euramerican's bark obtained were 12.5 and 19.2%, respectively based on dry weight of bark. According to Stiasny Number of populus deltoids (42%) and populus euramerican (52%), the amounts of phenolic compounds obtained were 5.25 and 9.98%, respectively (based on dry weight of bark).The total tannin of populus deltoids and populus euramerican obtained were 1.3 and 1.2 % based on dry weight of bark, respectively. The amounts of condensed tannin obtained were 0.24 and 0.45%, respectively. According to the results, the amount of extractive materials of populus euramerican bark is 54% more than populus deltoids and also the phenolic compounds and condensed tannin of euramerican are twice as that of deltoids.