@article{ribeiro_barreto_coelho_2013,  title={Application of foam column as green technology for concentration of saponins from sisal (Agave sisalana) and Juá (Ziziphus joazeiro)},  volume={30},  ISSN={0104-6632},  url={https://doi.org/10.1590/S0104-66322013000400002},  DOI={10.1590/S0104-66322013000400002},  number={4},  journal={Brazilian Journal of Chemical Engineering},  publisher={Brazilian Society of Chemical Engineering},  author={Ribeiro, B. D. and Barreto, D. W. and Coelho, M. A. Z.},  year={2013},  month={Oct},  pages={701–709} }