## 3 Results  
### Dominant Microorganisms in Sweet Potato Samples and Their Variation with Temperature During Storage  
In the case of the sweet potato samples, the presence and concentration of characteristic microbial groups were determined. These microbes are assumed to be present in larger numbers in the products and affect their quality over the shelf life.  
The findings yielded from the experiment on sweet potatoes revealed that no proliferation of psychotrophic and anaerobic microorganisms was observed at a temperature of 5 \({}^{\circ}\)C, either on the initial testing day or in the subsequent storage period (Table 1). Yeasts and moulds were detected in all fresh samples, and their numbers remained relatively constant during storage. Spore-forming bacteria and members of the _Enterobacteriaceae_ family, if present, were only found in low numbers in the fresh samples. While spore formers tended to stagnate or decrease during storage, members of the _Enterobacteriaceae_ family increased by 1.5 orders of magnitude. The sweet potato samples were characterised by a considerable number (usually between 2 and 4 orders of magnitude) of the microbial groups, as shown in Figure 2. It was observed that the population of these microorganisms exhibited an increase during the storage period.  
The findings indicate that the predominant culturable microbiota consists of mesophilic lactic acid bacteria, which demonstrated survival and multiplication capabilities in vacuum-packed products. Furthermore, the study suggested that enterobacteria may also play a role in the spoilage process by increasing their cell number by 1.5 orders of magnitude.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Groups of Microbes** & \multicolumn{2}{c}{**Bonita**} & \multicolumn{2}{c}{**Covington**} \\  & **Fresh** & **Stored** & **Fresh** & **Stored** \\ \hline Psychotrophic microorganisms & \textless{}1.00 & \textless{}1.00 & \textless{}1.00 & \textless{}1.00 \\ Anaerobic microorganisms at 5 \({}^{\circ}\)C & \textless{}1.00 & \textless{}1.00 & \textless{}1.00 & \textless{}1.00 \\ _Enterobacteriaceae_ (on VRBG) & \textless{}1.00 & \textless{}1.00 & \textless{}1.00 & \textless{}1.49\pm 0.20\) \\ Spore-forming bacteria & \textless{}1.00 & 1.00 \(\pm\) ND \({}^{\beta}\) & 1.39 \(\pm\) 0.36 & \textless{}1.00 \\ Yeasts/moulds & \textless{}2.00 \(\pm\) 0.00 \({}^{\alpha}\) & 2.30 \(\pm\) ND \({}^{\beta}\) & 2.16 \(\pm\) 0.15 & \textless{}2.00 \\ \hline \end{tabular}  
* The detection limit for yeasts and moulds is 100 CFU/mL. (corresponds to 2 log\({}_{10}\) CFU/mL), and out of the three parallels, one resulted in a colony number less than the detection limit. In these cases, the average and the standard deviation were calculated only from two data points. \({}^{\beta}\) Out of the three parallels, two resulted in a cell number of the investigated group of microbes under the detection limit; thus, the value of the only positive sample is indicated, and the standard deviation was not determined (ND).  
\end{table}
Table 1: Log\({}_{10}\) CFU/g values of specific microbial groups comprising the microbiota of samples of the Bonita and Covington sweet potato varieties examined before and after storage, with standard deviations.  
The results of the microbiological examination of the tested sweet potato varieties demonstrate that they are characterised by nearly identical microbial contamination after washing, peeling, and slicing, and no significant difference is observed in the initial microbial counts. However, in the case of Bonita (white variety), a significant decrease in lactococci numbers was observed after storage, and this was a variety of sweet potato where initial microbial numbers had not been elevated to a substantial degree.