Extraction and characterization of collagen from the skin of Amazonian freshwater fish pirarucu oleh K.C.R. Carpio, R.S. Bezerra, T.B. Cahú, F.T.D. do Monte, R.C.A. Neri, J.F. da Silva, P.R. dos Santos, R.P. Carvalho, D.M.L. Galeno, A.J. Inhamuns