ŻYWNOŚĆ. Nauka. Technologia. Jakość, 2005, 3 (44) Supl., 264  – 273

WŁADYSŁAW MYJAK

ATTEMPTS TO DETERMINE PHYSICOCHEMICAL CHANGES IN BOYINE HIDES DURING THE  BEAMHOUSE PROCESSES

Summary

The object of this study were tanned hides of Iow black and white race cattłe. During the investiga-tions, there were determined changes in the composition of proteins contained in bovine hides that oc-curred during the individual phases of beamhouse processes. The following parameters were determined in the hides: dry matter, total protein, collagen, total amount of extractable protein, free fat, minerał com-ponents, and, also, the shrinkage temperaturę was taken.

It was found that the beamhouse processes caused high quantitative changes in bovine proteins. The highest protein loss was noticed during the liming and bating. It was also observed an explicit impact of liming substances on the composition of a bovine hide: along with the increase in a Na₂S concentration, there was an increase in the amount of collagen passing into the solution. A concentration of 0.12% of Na₂S in the bating bath was the critical value; if this value was exceeded, a drastic degradation of protein occurred. The bovine collagen was morę resistant to the action of Ca(OH)₂ than of Na₂S. The temperaturę of liming significantly influenced the content of protein extractable during the bath, thus, it should not exceed 30°C. A close dependence between the shrinkage temperaturę and the quantity of collagen was observed: with the decrease in the content of collagen in hide, the shrinkage temperaturę sank during the individual phases of beamhouse processes.

The conciusidn is that beamhouse processes during which hides arę prepared for tanning cause a per-centage increase, by approximately 14%, in the collagen content in generał protein, and this fact explains the increase in reactivity of liming leather to minerał tannins.

Key words: bovine hides, beamhouse processes, tanning of hides, collagen