1. Acknowledgments This work has been financed by the European Fund for Regional Development and the Romanian Government in the framework of Sectoral Operational Programme CCE-AXIS 2, Operation 2.1.2, through the INNOVA-LEATHER project: «Innovative technologies for leather sector increasing technological competitiveness by RDI, quality of life and environmental protection» – contract no. 242/20.09.2010 ID 638 COD SMIS – CSNR 12579 Madalina Georgiana Albu 1, Ioannis Ioanidis 1, Mihaela Violeta Ghica 2, Viorica Deselnicu 1, Ciprian Chelaru 1, Gheorghe Coara 1 Hydrolyzed collagen is a natural protein which is successfully used for cosmetic formulation purposes. The aim of this study was to obtain collagen hydrolysate from wet white leather wastes which were pre-tanned with organic (oxazolidine and oxazolidine-resorcinol) and mineral (Titanium-aluminium complex) tanning agents. Solutions of 10% collagen hydrolysates named A, B and C were characterized by dry substance, amide nitrogen, ash, primary amino groups, fatty, pH, FT-IR spectroscopy and rheological analyses. The results demonstrated that the collagen hydrolysate characteristics are influenced by the raw materials (wet white leather) and the properties allow them to be used in manufacture of cosmetic products. 1 INCDTP - Division: Leather and Footwear Research Institute, Collagen Department, Bucharest, Romania, 2 “Carol Davila” University of Medicine and Pharmacy, Faculty of Pharmacy, Physical and Colloidal Chemistry Department, Bucharest, Romania Collagen Hydrolysate Preparation Wet –white leather wastes acidic hydrolysis of wet white leather wastes at 125°C during 8h Lyophilized hydrolysates Solubilization of hydrolysates Physical-chemical analyses Rheological analysis by rotational viscometer Multi-visc Rheometer-Fungilab FT-IR for collagen hydrolysates were recording using a FT-IR 6000 spectrofotometer with ATR reflection system MK II Golden Gate Single (Jasco) Hydrolysate A, B and C Basic characteristics of collagen hydrolysates CharacteristicsHydrolysate AHydrolysate BHydrolysate C Dry substance, %9.489.748.76 Amide nitrogen in dry substance, %1.67 / 17.621.31 / 17.811.55 / 17.69 Proteic substance, %9.39 / 99.059.74 / 100.008.71 / 99.43 Primary amino groups in dry substance, %0.05 / 0.530.01 / 0.570.06 / 0.66 Fat in dry substance, %free pH for 5% solution3.923.173.42 Rheological behaviour of collagen hydrolysates: a) A hydrolysate; b) B hydrolysate; c) C hydrolysate Spectral characteristics of collagen hydrolysates SampleA III / A 1450 A I / A II Hydrolysate A0.7121.454 Hydrolysate B0.7081.551 Hydrolysate C0.7131.374 Amide A of hydrolysates A, B and C determined by FT-IR spectra Three types of collagen hydrolysates were obtained by acidic hydrolysis from wet white leather wastes tanned with oxazolidine, titanium-aluminium complex and oxazolidine-resorcinol. All the obtained hydrolysates contained high amount of collagen and the amide nitrogen in dry substance is between 17.62 and 17.81, the hydrolysate having very close value of molecular weight. The dynamic viscosity was 2.75cP for hydrolysate A, 2.41cP for hydrolysate B, and 3.18cP for hydrolysate C respectively, with a determination coefficient R 2 higher than 0.9960. The FT-IR results are in accordance with rheology behavior, the properties of hydrolysates allowing them to be used in manufacture of cosmetic products.