## 3 Results and Discussion  
As the first secretion of the mammary gland, colostrum is characterized by many nutrients and biologically active compounds. However, it is also a source of microorganisms that can adversely affect its quality and consumer safety. Therefore, it has been assumed that the number of microorganisms in raw colostrum samples should not exceed 5 log cfu/mL for the total bacterial count and 4 log cfu/mL for coliforms [37]. In a study by [PERSON] et al. [37] in heat-treated samples, these values were as high as 4.3 log cfu/mL and 2.0 log cfu/mL. This may pose a significant risk of pathogen transmission. Furthermore, the presence of microorganisms also decreases immunoglobulin activity due to the binding of bacteria to free immunoglobulins in the small intestine or blocking the transport of IgG molecules by intestinal epithelial cells [38]. As a result, the absorption of colostrum components is impaired, and the transfer of passive immunity is reduced. Therefore, bacterial contamination, together with Ig concentration (>50 mg/mL), is the basic criteria for assessing colostrum quality, i.e., its nutritional value and microbiological safety [37]. Microbiological analysis of freeze-dried colostrum samples showed the absence of pathogenic bacteria: _Salmonella_ spp., _S. aureus_ (coagulase positive), _L. monocytogenes_ and _Cronobacter_ spp. However, normal inhabitants of bovine skin and mucosa (NI), environmental contaminants (EC) and faecal contaminants (FC) were present. Total bacteria count (TCB), including individual samples, was determined in the log at 3.91-5.54 cfu/g. Twenty percent of the samples were above the accepted levels of microbial contamination, as defined by [PERSON] et al. [35]. According to Table 2, the highest differences in the tested colostrum samples were determined for microorganisms included in the NI group. In individual microbial groups (THMC including TSt, TStr or LAB and TYMC), statistically significant differences (\(p\leq 0.05\)) were confirmed, depending on the batch. The differences in the FC group counts could affect the THMC count. In this case, the statistical significance of the results was determined for _Enterobacteriaceae_ (TEb), including _E. coli_. In contrast to TEb, which was determined in all colostrum samples, the detection of _E. coli_ was incidental. The counts of faecal coliforms (Ecc) were noticeable but not statistically significant. The comparable numbers of identified microorganisms were present in all samples regardless of their batch in the EC group. In the present study, the application of cold plasma air, nitrogen and oxygen as the working gases resulted in a noticeable reduction in the total microbial count (TBc). Unfortunately, the differences were not statistically significant. Depending on the gas used, a decrease of 0.68 log cfu/g (air), 0.83 log cfu/g (nitrogen) and 0.92 log cfu/g was achieved. It is confirmed that the level of microbial inactivation relies on the mixture of different reactive forms of ions, free electrons and molecules generated in the plasma and reactive nitrogen species (RNS), oxygen species (ROS) and hydrogen species (RHS) are the most important active plasma agents formed. Their number and type depend on the plasmonizer system and the technological parameters, including the ionizing gas [39]. In the present study, the greatest decontamination effects were obtained in oxygen as the working gas. In the case of TBc, a minimum reduction of 1 log was not achieved. These effects of plasma treatment were confirmed for THMC (1.02 log reduction) and THPC (1.24 log reduction). Similar results were observed for the reduction of _Enterobacteriaceae_-by 1.16 log and slightly lower for _E. coli_-by 0.96 log (Table 3). Due to their cell wall structure, Gram-negative rods are more sensitive to reactive nitrogen and oxygen species (RNOS) than Gram-positive bacteria [40; 41; 42]. Our study confirms these findings. Inactivation of _Enterococcus_ spp., _Staphylococcus_ spp., and _Streptococcus_ spp., was no greater than 0.78 logs