Resumo

CASTRO MANDUJANO, Nino; YEPEZ, Ana María  e  PASTOR DE ABRAM, Ana. Comparison of three methods to determine the percentage of tannins with the method of the ASTM D6401 norm for "tara", "quinual", "mimosa" and "pino". Rev. Soc. Quím. Perú [online]. 2013, vol.79, n.4, pp.381-387. ISSN 1810-634X.

Tannins are considered as a group of phenolic complex substances that are widely distributed in the plant kingdom and can be found in the stems, leaves, seeds, bark, roots, fruits, etc. In the tanning process is very important to know the percentage of tanning of the plant, because according to these parameters, specific vegetable tanning can be done. In the investigation, it is analyzed the percentage of tannins and non-tannins of the "tara" (Caesalpinea spinosa), and "quinual" (Polilepis incana) of Peru, "mimosa" (Acacia mearnsii) of Brazil, and "pino" (Pinnus radiata) of Chile, by three different methods: the modified permanganate method, the CIATEC-Mexico method and LATU-Uruguay method. These three methods compared with the official method according to ASTM D6401 norm. It is also determined the total percentage solids and percentage of soluble solids. Analyzing the results, it can be observed that the CIATEC method is the faster one (maximum 6 working hours), with acceptable precision and accuracy, since applying the official method the result are obtained in at least 3 days.

Palavras-chave : Caesalpinea spinosa; Polilepis incana; Acacia mearnsii; Pinnus radiata; tannins; non-tannins.

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