Tannin Extraction from the Bark of <i>Pinus oocarpa</i> var. <i>oocarpa</i> with Sodium Carbonate and Sodium Bisulfite

Vieira, Michel Cardoso; Lelis, Roberto Carlos Costa; Silva, Bruno Couto da; Oliveira, Gisely de Lima

doi:10.4322/floram.2011.017

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Artigo de Pesquisa • Floresta Ambient. 18 (1) • Jan-Mar 2011 • https://doi.org/10.4322/floram.2011.017 copy

Tannin Extraction from the Bark of Pinus oocarpa var. oocarpa with Sodium Carbonate and Sodium Bisulfite

Extração de Taninos da Casca de Pinus oocarpa var. oocarpa com Carbonato de Sódio e Bissulfito de Sódio

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Tannin Extraction from the bark of Pinus oocarpa var. oocarpa with sodium carbonate and sodium bisulfite. The objective of this study was to evaluate the tannin extraction potential taken from the bark of Pinus oocarpa var. oocarpa. Nine treatments were performed; the bark was submitted to extraction using water and water containing different concentrations of sodium carbonate and sodium bisulfite. The mixture was kept under reflux for two hours. The extracted contents, the polyphenol found in the extracts (Stiasny number), the tannin yield, the non-tannin yield and the tannin reactivity through UV method were all determined. The results have revealed that it is possible to obtain high tannin content (approximately 39%) from the bark of Pinus oocarpa var. oocarpa by using water extraction when coupled with the addition of salt. The treatment having (8%) of sodium carbonate provided a greater yield of condensed tannins, underlining the importance of utilizing this salt with this concentration during the extraction process. However, the extracts must be evaluated according to other important wood-gluing properties, such as viscosity and gel time.

Keywords:
Pinus oocarpa; bark; tannins.

Table 1 Mean values of the Stiasny number (SI), % of extractives, % of tannins and % of non-tannins in the bark of Pinus oocarpa var. oocarpa.

Treatment	SI (%)	% Extractives	% Tannins	% Non-tannins
T1	65.56^C	24.84^F	16.24^F	8.60^B
T2	85.72^A	30.94^D	26.40^D	4.54^C
T3	89.70^A	35.74^C	32.10^C	3.69^C
T4	90.54^A	43.92^B	39.74^A	4.18^C
T5	74.82^B	48.84^A	36.50^B	12.34^A
T6	84.64^A	19.86^G	17.56^F	2.30^C
T7	72.28^B	26.70^E	19.28^E	7.42^B
T8	74.62^B	26.52^E	19.82^E	6.70^B
T9	84.00^A	23.28^F	19.48^E	3.80^C

Table 2 Mean values of polyphenol content from the bark of Pinus oocarpa var. oocarpa using the UV method.

Treatment	Reactivity (UV) %
T1	85.32^B
T2	99.25^A
T3	94.51^A
T4	96.90^A
T5	95.57^A
T6	98.09^A
T7	99.21^A
T8	99.50^A
T9	98.29^A

Table 3 Mean pH levels of extract acquired from the bark of Pinus oocarpa var. oocarpa.

Treatment	pH
T1	3.01^F
T2	5.53^D
T3	7.50^C
T4	8.06^B
T5	8.74^A
T6	3.20^F
T7	3.20^F
T8	3.52^E
T9	3.32^E

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[1] CORRESPONDENCE TO Michel Cardoso Vieira Departamento de Produtos Florestais, Instituto de Florestas, Universidade Federal Rural do Rio de Janeiro - UFRRJ, BR-465, Km 7, CEP 23890-000, Seropédica, RJ, Brasil e-mail: mceflorestal@ig.com.br