R.F. González’s scientific contributions

An evaluation was made of the efficiency of three extraction systems on yields and selectivity of condensed tannins from the bark of Pinus chihuahuana and Pinus durangensis collected in the State of Durango, Mexico. Tannins were extracted using boiling water, 70% aqueous acetone and 80% aqueous ethanol. Stiasny number and extract percent by weight were used to quantify condensed tannins. For P. Chihuahuana condensed tannins ranged from 3.5 to 7.15% with a Stiasny number of 80.87%, while for P. durangensis the Stiasny value reached 84.82% with 15.88% tannins. The best results were obtained by extracting the bark with 70% acetone. Statistically significant differences were found between the extraction systems and between species. The results demonstrated that the bark of P. durangensis was an important source of condensed tannins.