PHYSICOCHEMICAL PROPERTIES OF COLLAGEN, GELATIN AND COLLAGEN HYDROLYSATE DERIVED FROM BOVINE LIMED SPLIT WASTES

摘要

Collagen, gelatin and collagen hydrolysate were prepared from bovine limed split wastes by different preparative processes. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that the molecular weight distribution of collagen was very narrow (about 200 and 100kDa for β and α chains respectively) compared with those of gelatin (less than 300kDa and wide distribution) and collagen hydrolysate (less than 50kDa and wide distribution ). The isoelectric points of collagen, gelatin and collagen hydrolysate were 8.26, 4.88 and 4.54 respectively determined by Zeta potential titration. Circular dichroism (CD) spectra revealed that there were two peaks, a positive peak around 221nm and a negative peak around 192nm for collagen, which are the characteristics of collagen triple helix. However, gelatin and collagen hydrolysate lacked any positive peaks around 220nm, suggesting random coils. The denaturation temperature of collagen was about 37.5℃ determined by the viscosity method, the helix-coil transitions for gelatin and collagen hydrolysate were not present in the heating process. Collagen reaggregated to fibrils at 35℃ monitored at 313nm. In contrast, gelatin and collagen hydrolysate lost the ability of fibril formation. Collagen was more resistant to trypsin hydrolysis compared with gelatin and collagen hydrolysate. In addition, the collagen membrane exhibited superior features such as higher enthalpy, greater network structure and better physical/mechanical properties compared with those of the gelatin membrane. Therefore, collagen isolated from limed split wastes can be a high value product due to its special characteristics and has many potential future applications in biomaterials, functional additives, cosmetics and pharmaceutical industries.