## 4 Discussion
The results led to the assumption that packaging materials coated with Ut and Fb layers could be used to preserve cooked ham during short-term storage in air conditions. The described findings demonstrated that coatings containing 5% of the _U. tomentosa_ or 5% of the _F. betulina_ extracts with the addition of a decreased amount of nano ZnO did not inhibit the growth of mesophilic bacterial strains for a sliced cooked ham that was stored for 96 h, but decreased their number when compared to the ham stored in uncovered bags. Comparing the influence of active layers on the total count after 48 h, it may be mentioned that the most effective packaging material was the bags covered with the Ut coating. Comparing SEM micrographs of the \"0\" samples and ham slices after storage, it was observed that the most similar microstructures were the surfaces of the ham before storage and the ham slices stored in bags with Ut coating, confirming its effectiveness. The results of this study determined that the number of mesophilic microbes from ready-prepared, sliced cooked ham samples purchased from a local market (sample \"0\") was almost 4 log\({}_{10}\) CFU/g, which is seen as an unsuitable number of microorganisms for the sliced ham to be consumed [28]. The expiration date (\(\pm\)2 days) of the product could have been one of the reasons. Moreover, the producer suggested ham consumption within 2-3 days after package opening, meaning that a total count should be on the level acceptable for consumption after 48 h of ham storage. Unfortunately, according to [PERSON] et al. [28], ham samples were not acceptable for consumption after 2 days of storage. However, according to another author [29], an acceptable level of the total count of cooked ham products is generally set to 6 log\({}_{10}\) CFU/g. It means that ham slices stored in uncoated and in active packaging were still acceptable to be consumed after 48 h of storage. While after 96 h of storage, the only suitable samples for consumption were the ham slices stored in bags covered with the Ut coating. It should be added that the ham was purchased in a local market and sliced by the shop assistant after the package opening. The high level of mesophilic bacteria observed for the sample \"0\" proved that the ham must have been contaminated during slicing. It may be predicted and even suggested that the number of bacteria in sample \"0\" was too high to be decreased by the active substances which were released from the layers. Considering the presence of pathogenic microorganisms, it should be emphasized that neither the coliform bacteria nor _S. aureus_ cells were detected in the cooked ham slices after 48 h and 96 h of storage in PP bags coated with the Ut and Fb layer. From this point of view, these ham slices were still suitable for consumption even after 96 h of storage. In summary, the influence of Ut coating on the quality of sliced, cooked ham was noted, confirming that packaging covered with this active layer can be used for short-term storage. It may be predicted that if ham slices are not contaminated during slicing, the samples will be stored for a longer time than the time suggested by producers. Similar results were obtained in the previous study [2]. The bags and spacers coated with the layer containing 50% of the mixture of _Glycyrrhiza_ L. and _Scutelaria bialensis_ extracts were proved to be the best packaging material for ready-prepared chicken sausages which were purchased from a local butcher's shop and which were contaminated during slicing. This active packaging material preserved and maintained the quality of sausage slices after short-term storage (72 h) at 5 \({}^{\circ}\)C. [PERSON] et al. [4] performed similar experiments. The authors purchased sliced cooked ham with an expiration date of \(\pm\)3 days. According to the authors, the producer suggested ham consumption within 1-3 days after the package opening. It has to be underlined that the ham analyzed by the authors was not sliced by the shop assistant, but it was already sliced.