Study On Tanning Technology Of Farmed Sturgeon Skin

Sturgeon skin which was provided by Hubei Tianxia Sturgeon (Group)Limited Company, the biggest germplasm resources center with the mostvarieties and the largest scale in the world, was chosen as the object inthis study. Firstly the histological structure of sturgeon skin was analyzed,and a leather-making scheme for sturgeon skin was designed according tomodern tanning technology and practical experience from sevevalexperiments about sturgeon leather making. Then operating conditions ofseveval key processes such as liming, bating, bleaching and tanning,which had much effect on the properties of leather, were studied andoptimized. Finally according to the results of the enlarging pilot test,processes of sturgeon leather-making technology were adjusted.1.In the liming experiment of sturgeon skin, the use of amine limingauxiliary agent could reduce the electrostatic repulsion between collagensof liming sturgeon skin and restrain the swelling of liming sturgeon skin,effectively avoiding the looseness of ganoid scales on sturgeon skin in theprocesses of liming-deliming. And20degrees centigrade was determinedas the liming temperature, liquor ratio was8, the dosages of calciumhydroxide, liming auxiliary agent and degreaser were respectively2%,3%, and0.5%as optimal liming conditions.2. Trypsin had stronger hydrolysis on the surface collagen than thedeeper, so modified glutaraldehyde was chosen to pretreat sturgeon skinafter deashing to avoid loose grain and ganoid scales. And the optimumconditions for the bating process were determined by orthogonalexperiment: the bating temperature was32degrees centigrade, liquorratio was8, pH was7.5～8.0, the dosages of modified glutaraldehyde,trypsin and degreaser were respectively0.6%,0.5%,0.5%, bating timewas4h. After bating, sturgeon skin was bleached with KMnO4-NaHSO3bleaching system, which was controlled easily and of good bleachingeffect, little pollution. 3. The influences of the dosage of chrome tanning agent and modifiedglutaraldehyde on the properties of sturgeon leather were investigatedrespectively, and then tanning sturgeon skin with different dosageproportioning chrome-modified glutaraldehyde simultaneously wasstudied. Experimental results showed that: modified glutaraldehyde couldnot only promote the absorption of chrome, but also improve thetoughness of ganoid scales on sturgeon leather; tanning with4%chrometanning agent and8%modified glutaraldehyde, the Cr2O3content ofwaste liquor was rather low, greatly reducing chromium pollution, and theleather shrinkage temperature could reach90degrees centigrade whichwas up to the standards of upper and garment leather in light industry.4. The enlarging pilot test for sturgeon tanning technology was carriedout, and the result showed that the sturgeon skin grain was easy to bechafed by small boney spikes on the ganoid scales of another sturgeonskin in high-intensity mechanical action. So the process of softeningganoid scales was considered to be adjusted to an earlier stage of thebeam house for sturgeon skin, and softening process was adjusted to carryout after fleshing and in the soaking solution, which could reduce the useof NaCl. Properties of sturgeon leather of enlarging pilot test for sturgeontanning technology after process adjustment were satisfying. Thus,finalized sturgeon leather-making technology scheme was as follows：soakingâ†'fleshingâ†'pickingâ†'limingâ†'delimingâ†'batingâ†'bleachingâ†'pickingâ†'tanningâ†'solvent degreasing.