Study Of Collagen Hydrolyzate, Extracted From The Waste Chrome Tanning Dander

The serious problems which tannery industry faces are the pollution to the environment and the extremely waste of resources. In the tannery industry, it is accepted that 1 ton of salted hides yields only 200kg of leather (about 20% of the initial hide weight), and more than 600 kg of solid waste (more than 60% of the initial hide weight) is discharged as rubbish. On one hand, it causes the serious waste of high-grade rawhide resource. On the other hand, it does great harm to environment. Since 1980s, due to the increasing of local restrictions on land disposal and escalating of landfill costs, the developed countries had shifted their industry that may cause serious pollution to the developing ones. Many researchers have been focusing their studies on how to use the tannery solid waste efficiently. Since 1990s, with the increasing of severe worldwide ecological problems as resource and environment, the leather industry confronts the challenge of "sustainable development strategy". It has a great prospect to reuse the tannery solid waste.In order to extract collagen from tannery solid waste, two problems should be solved firstly. One is the removing of chromium from the chrome shavings, and the other is the obtaining of shorter peptide chains by destroying the collagen macromolecule chain. To remove the chromium from the chrome shavings, the method of acid, chelate, peroxide combined with chelate and comprehensive method are used. Among these, the last one is the best. The de-chroming rate can reach 99.98 percent of the total chrome content.To obtain the hydrolysis of collagen, such ways as acid, alkali and alkaline proteinase are used. The effect of different methods to the performance index is discussed. The color of the hydrolysis of collagen by alkali method is the best, but its ash content is the highest. When hydrolization is conducted by alkaline proteinase, the reaction time is the shortest, and the ash content is the lowest. When the sample is hydrolysized by acid, the gel effect may be observed easily. Few differences are found in the TKN (Total Kjeldahl Nitrogen) of all the samples obtained by all the ways used.The hydrolysis product is being used to make edible wrap, which is under way.The molecular weights of hydrolysis product were estimated by SDS-PAGE (polyacrylamide gel electrophoresis in sodium dodecylsulfate) using a Laemmli System, the molecular weight range from 14,400 to 97,400.