Ultrasound-assisted Extraction of Polyphenols from Red-grape (Vitis Vinifera) Residues G. González-M G. González-M, X. Usaquén-C X. Usaquén-C, M. Martínez-R M. Martínez-R and H. Aya-Baquero H. Aya-Baquero DOI: 10.1051/IUFoST:20060638