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 Albu1, Ioannis Ioanidis1, Mihaela Violeta Ghica2, Viorica Deselnicu1, Ciprian Chelaru1 , Gheorghe Coara1

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 analysesRheological analysis by rotational viscometer Multi-visc Rheometer-FungilabFT-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

Characteristics Hydrolysate A

Hydrolysate B

Hydrolysate C

Dry substance, % 9.48 9.74 8.76Amide nitrogen in dry substance, %

1.67 / 17.62 1.31 / 17.81 1.55 / 17.69

Proteic substance, % 9.39 / 99.05 9.74 / 100.00 8.71 / 99.43Primary amino groups in dry substance, %

0.05 / 0.53 0.01 / 0.57 0.06 / 0.66

Fat in dry substance, % free free freepH for 5% solution 3.92 3.17 3.42

Rheological behaviour of collagen hydrolysates: a) A hydrolysate; b) B hydrolysate; c) C hydrolysate

0 50 100 150 200 250

0

1

2

3

4

5

6

7

Sh

ea

r st

ress

, Pa

Shear rate, s-1

y = 0.02744x +0.00657

R2 = 0.99945

0 50 100 150 200 250

0

1

2

3

4

5

6

Sh

ea

r st

ress

, Pa

Shear rate, s-1

y = 0.02421x - 0.08386

R2 = 0.99825

0 50 100 150 200 250

0

1

2

3

4

5

6

7

8

Sh

ea

r st

ress

, Pa

Shear rate, s-1

y = 0.03186 x - 0.03003

R2 = 0.99903

Spectral characteristics of collagen hydrolysates

Sample AIII / A1450 AI / AII

Hydrolysate A 0.712 1.454

Hydrolysate B 0.708 1.551

Hydrolysate C 0.713 1.374

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 R2 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.