# Impact of Selected Yeast Strains on Quality Parameters of Obtained Sauerkraut
## 3 Results and Discussion
### Colour and Aroma Profile  
Food colour is often associated with product quality and serves as a key feature by which consumers evaluate and select products [41]. As consumers typically evaluate products visually before tasting them, colour plays a crucial role in consumer perception. Treatments applied to cabbage significantly affect its colour [42]. This is attributed to changes in the composition of antioxidant compounds, pH increase, the formation of browning pigments and other factors [43]. The CieLAB method was employed to assess the colour of sauerkraut and to determine the influence of yeast addition during fermentation (Table 6). Significant differences were found between the products in the a*, b*, c* and h0 colour parameters. All sauerkraut samples analysed showed similar lightness values ranging from 62.6 to 66.7. The control sample displayed the highest values for the a*, b*, C* and h0 coefficients, indicating a smaller share of green (a*), a greater share of yellow (b*) and a higher colour intensity (C*) compared with those in sauerkraut produced without yeast addition. The h0 parameter values were in the yellow range (85.8-88.6). The \(\Delta\)e coefficient indicates the colour deviation from the control sample, with the highest differences observed in sauerkraut fermented with _W. anomalous_ Wa22 and _D. hansenii_ Dh17. \(\Delta\)e exceeding 6 indicates significant differences between two samples [44]. The aroma of sauerkraut was assessed in terms of overall aroma acceptability and intensity, and seven aroma attributes: typical, acetic, sulphur, green, metallic, animal and pungent. The highest scores were given to sauerkraut aroma profiles obtained without the addition of yeast and with the addition of _D. hansenii_ strains (Figure 1). These samples received the highest scores for the typical sauerkraut aroma, exceeding 6.5 points (Figure 2). Conversely, sauerkraut fermented with the _W. anomalous_ and _Rh. mucilaginous_ strainsperformed less favourably. Low scores were attributed to a low aroma intensity rather than the presence of specific off-odours. Sauerkraut produced with the _Cl. lusitaniae_ Cl6 culture had the highest aroma intensity (Figure 1). This observation is consistent with the results of HS-SPME-GC-MS analysis (Tables 3-5), which showed that these samples also had the highest concentration of volatile compounds. However, despite the increased odour intensity, the aroma acceptability of these samples deteriorated significantly. The typical aroma of sauerkraut received the highest scores, ranging from 5.8 to 7.3. The flavour of fermented cabbage is mainly influenced by components derived from the raw material, which undergo transformation during the fermentation process and thus represent a fundamental aspect of sauerkraut quality [45]. These components can be divided into two groups: the first group includes isothicyanates and other sulphur-containing volatile organic compounds (such as sulphides and thiols), while the second group encompasses a wide range of chemicals, including alcohols, aldehydes, acids, ketones, terpenes, hydrocarbons, esters, sulphur-containing compounds and others [31]. Another highly rated aroma characteristic is the floral aroma. Lactic acid and acetic acid can both act as precursors for the formation of esters, specifically ethyl lactate and ethyl acetate, respectively, which contribute to the fruity aroma. The strains of lactic acid bacteria (LAB) present largely influence the production of these esters [34]. The highest scores for this attribute were assigned to sauerkraut fermented with _Cl. lusitaniae_ Cl6 and _D. hansenii_ Dh31 yeasts. In both samples, elevated levels of esters, mainly ethyl acetate, were detected. However, these samples received relatively low overall acceptability scores, suggesting that higher ester concentrations may negatively affect aroma quality. Figure 1: Overall aroma impression and aroma intensity of sauerkraut produced with the addition of different yeast cultures based on a 10-point scale.