Optimization of condensed tannins extraction from Pinus Taeda bark

FERNANDEZ SOSA, ELIANA; FELISSIA FERNANDO ESTEBAN; RAMOS, SILVINA GABRIELA; CHAVE, GUADALUPE; AREA MARÍA CRISTINA

Congreso; Congreso Iberoamericano de Investigación en Celulosa y Papel; 2024

Abundant side streams of the forest industry, such as wood barks, sawdust, or needles, are underutilized and often burned for energy production. A circular bioeconomy further valorizes lignocellulosic waste to obtain high-added-value products. Bark can be employed in diverse chemical and materials production, such as adhesives. This work aimed to optimize condensed tannins extraction from Pinus taeda bark for adhesive application. Solid/liquid extractions were performed with ethanol/water as a solvent (Figure 1), according to a fractional factorial design (2k-1), considering the factors X1: ethanol concentration (30-70%), X2: temperature (50-80°C), X3: liquid/solid (L/S) ratio (8/1-15/1), and X4: time (1-2 h). The dependent variables were extraction yield, total polyphenol content, condensed tannins, and Stiasny number. Ethanol concentration and temperature significantly affected each of the responses; the L/S ratio did not have a significant effect on extraction yield, whereas time positively influenced condensed tannins and Stiasny number (reactivity with formaldehyde). Response surface methodology was used to optimize the screened variables (X1, X2, and X3) for enhanced condensed tannins and Stiasny number according to a central composite design (CCD). The time was fixed at 2 h, studying the behavior of the same dependent variables at five different levels of the independent variables. The optimal extraction condition was ethanol 65% v/v, 90 °C, and L/S ratio 8/1. The optimized extract presented 215.56±0.23 mg Catechin Equivalent/g extract and 81.87±5.93% of Stiasny number, suggesting that the obtained extract can potentially be part of adhesive formulations. The use of bark will improve profitability and reduce the global polluting load of the forest industry.