Strength properties, the amount of chrome compounds in leather, soluble matter in dichloromethane, and volatile matter were determined according to standards. Shrinkage temperature of chromed leather samples was determined as described in the literature using special equipment and replacing the distilled water with glycerol. The next step was to discover how the action of microorganisms affects derma collagen. The index, which is very sensitive to collagen structural changes, is the shrinkage temperature of hide. The results of hide shrinkage temperature determination did not show any serious changes in derma structure. For all samples, only a negligible decrease of shrinkage temperature was observed. This indicates that the action of microorganisms, which takes place only on the surface of the hide, does not affect the deeper layers of the hide. This remains true even when bacteria act in a very intensive manner. Therefore, it can be concluded that changes in shrinkage temperature do not reflects a level of hide deterioration when no chemical material is used for hide preservation, and collagen, accordingly, is not affected by this material. Another index which indicates a condition of preserved hide is the amount of ammonia released, which is formed when the hydrolysis of proteins begins due to the action of microorganisms. The data in Table 3 show that the 4-(Benzyloxy)phenol observable increase of the amount of extracted nitrogen begins only for unpreserved hide after 13 days of storage. This result confirms a proposition that hide can be stored at 4uC for 2 weeks without compromising its quality. In the case of vacuumed and salted hide samples, the increment of nitrogen content was negligible. One of initial symptoms of deterioration is a change to the exterior of the hide. As a result, a Diperodon comparison of the hide samples was carried out. The optical microscopy images are presented in Fig. 3. The exploration of images allowed the conclusion to be drawn that any observable changes to the outside and inside of the hide did not occur during the 22 day storage period. Furthermore, possible changes of the supermolecular structure during storage under vacuum were investigated. FTIR spectroscopy and DSC analysis were carried out for this purpose. The structural changes reflect in the FTIR spectra as changes of individual bands in both position and intensity. A comparison of the peak area values allows a conclusion to be drawn about the formation of functional groups and the degradation or formation of bonds during hide storage. The most typical bands in the spectra were chosen for evaluation of structural changes. From studying the spectra of the hide samples it can be seen that no novel peaks were identified, and there was no loss of existing peaks. This indicated that any serious changes in supermolecular structure of collagen do not occur during the 22 day storage period. On the other hand, the intensity of all peaks was found to increase. The authors hypothesise that, owing to the action of vacuum during storage, the collagen fibres slowly become closer, making the derma becomes denser, which leads to the increased peak intensity in spectra from the hide samples that were stored for 22 days. The results of DSC analysis are presented in Fig. 5 and Table 5. It 
can be seen that DSC curves have three distinct thermal effects. The first endothermic effect can be attributed to shrinkage of the hide. However, a more credible suggestion is the association of that effect with the removal of capillary moisture. It is known that the degree of linking of capillary moisture in collagen is higher when capillaries are smaller. Presumably, the closer proximity of fibres during storage under vacuum leads to a decrease of capillary dimensions, and accordingly.