# Impact of Selected Yeast Strains on Quality Parameters of Obtained Sauerkraut
## 3 Results and Discussion
### Principal Component Analysis (PCA)  
Figure 3 shows the results of the principal component analysis (PCA) conducted to measure the main groups of chemical components detected in sauerkraut (expressed as the sum of the concentrations of compounds from a given group), obtained using different yeast strains. The first component (PC1) described 62.2% of the total variance, while the second one, PC2, described 24.4% of it. Positive PC1 charges were associated with the content of most of the analysed volatiles and organic acids, while negative charges were associated with glucosinolate degradation products (GLS). For PC2, negative charges were related to the content of organic acids and terpen, while positive charges were associated with the levels of other components tested. The control sample, obtained without the addition of yeast, was located almost in the centre of the coordinate system, which indicates the average content of all the components analysed. To its left are the sauerkraut samples obtained with the yeasts _P. fermentans_ Pf9, _W. anomalus_ and _Rh. mucilaginousa_ Rm26. They contained lower amounts of the components analysed than the control sample did. Samples inoculated with _P.ferentans_ Pf9 stood out particularly in this respect. _Pichia fermentans_ was usually detected at the end of the \begin{table}
\begin{tabular}{l|r|r|r|r|r|r|r|r|r|r|r|r} \hline CIE L & 65.5 & 66.7 & 65.3 & 65.1 & 64.6 & 65.0 & 63.6 & 62.6 & 65.2 & 63.5 & 66.4 & 0.4 & ns \\ \hline CIE a\({}^{*}\) & 0.2 b & -1.3 a & -0.8 a & -1.0 a & -0.9 a & -1.4 a & -1.5 a & -1.0 a & -0.9 a & -1.4 a & 0.2 & * \\ \hline CIE b\({}^{*}\) & 29.9 c & 22.6 ab & 26.4 a-c & 25.0 a-c & 25.0 a-c & 25.0 a-c & 21.6 a & 24.7 ab & 25.9 a-c & 27.0 c & 26.9 b & 0.8 & * \\ \hline C\({}^{*}\) & 29.9 c & 22.7 ab & 26.5 a-c & 25.0 a-c & 25.0 a-c & 25.0 a-c & 21.6 a & 24.7 a-c & 25.9 a-c & 27.0 c & 26.9 b & 0.8 & * \\ \hline h\({}^{0}\) & 88.6 b & 86.2 ab & 87.3 ab & 87.7 ab & 87.9 ab & 86.8 ab & 85.8 a & 87.7 ab & 87.7 ab & 88.2 ab & 86.9 ab & 0.4 & * \\ \hline \(\Delta\)e & 0.0 & 7.5 & 3.6 & 5.1 & 5.1 & 5.3 & 8.8 & 6.1 & 4.2 & 3.7 & 3.6 & 0.8 & \\ \hline \end{tabular} \({}^{1}\) SEM—standard error of means; \({}^{2}\) Sig.—significance; \({}^{*}\)—significance at 0.05 according to the least significant difference; ns: not significant. Values with different Roman letters (a–c) of the same parameter (in rows) indicate statistically significant differences at \(p<0.05\); n = 5. The concentration of a specific parameter is represented by a colour gradient ranging from dark red (lowest concentration) to dark green (highest concentration).  
\end{table} 
Table 6: A heatmap of CIELab values of sauerkraut produced with the addition of different yeast. Figure 3: Principal component analysis plot for the chemical composition of sauerkraut produced with different yeast strains (**a**) and for the corresponding loadings of selected chemical composition parameters of the samples (**b**). fermutation of sauerkraut under anaerobic conditions [4]. In our previous research, _P. fermentans_ was responsible for the production of the largest amount of volatile compounds on model substrates [5]. The introduction of cells of this microorganism into the fermentation process of sauerkraut resulted in a significant reduction in the amount of all components present in the product, both non-volatile, such as lactic acid, and volatile. _Pichia fermentans_ is a typical beverage spoilage yeast found in apple juice, beer, soft drinks, must and wine [47]. It can assimilate a wide range of different carbon sources, including hexoses such as glucose and pentoses such as xylose [48]. Similarly, the yeast species _W. anomulus_ is considered a yeast spoilage species [49]. Due to its aerobic metabolism, it develops slowly in the absence of oxygen [50]. This type of phenomenon was observed in the sauerkraut samples analysed. This strain neither caused excessive deacidification, which is its characteristic feature, nor did it produce large amounts of metabolites that negatively affect the quality.