# Microbiological and Sensory Quality of Artisanal Sour Cream
## 3 Results and Discussion
### Principal Component Analysis  
Principal component analysis (PCA) was performed to investigate the relationships between the physicochemical, microbiological, and sensory variables of the cream samples (Figure 6) and to evaluate the distribution and grouping of each sample (Figure 7). The first two principal components (PC1 and PC2) explained 17.41% and 13.50% of the total variance, respectively, for a total of 30.91%. Although the explained variance is relatively modest, the distribution of variables and samples in the PCA charts provides useful insights into the differentiation of cream characteristics. As shown in Figure 1, PC1 (horizontal axis) separates the samples mainly on the basis of sensory and microbiological characteristics. On the positive side of PC1, there is a clear association with off-flavours and higher counts of _Enterobacteriaceae_ and _Staphylococcus aureus_, indicating spoilage, microbial contamination, and reduced sensory quality. In contrast, the negative side of PC1 is associated with diacetyl odour, diacetyl flavour, characteristic cream flavour, and characteristic cream odour, indicating characteristics related to freshness and desirable sensory quality. This means that PC1 effectively distinguishes between samples of higher sensory quality and those with signs of spoilage or microbial deterioration. In contrast, PC2 (vertical axis) appears to separate the samples according to physicochemical characteristics. The positive side of PC2 is mainly influenced by pH, PUFA content (especially n-6 PUFA), and lactose, suggesting a relationship with fermentation processes, lipid composition, and sugar content. The negative side of PC2, on the other hand, is determined by fat content, dry matter content, and creaminess, indicating samples with a richer texture and composition but potentially lower acidity or freshness indicators. This means that PC2 represents a gradient from chemically richer, more textured samples to samples with lower acidity and lipid oxidation potential. Figure 6: Loading plot of the first two principal components after Varimax rotation. Figure 7 shows the projection of the individual cream samples into the PCA space. The wide scatter of points reflects a high degree of heterogeneity in the physicochemical, microbiological, and sensory properties of the samples. Sample 2 (marked red in Figure 7) is clearly separated along the positive axis of PC1, indicating a unique profile possibly due to increased microbial contamination or pronounced off-flavour development, as shown by the association with spoilage-related variables. Conversely, samples 15 and 9 (marked green in Figure 7) on the negative side of PC1 are closely associated with diacetyl flavour and odour, which may reflect the influence of beneficial microbial cultures or spontaneous fermentation contributing to an enhanced butter flavour typical of fresh, well-fermented cream, with no evidence of microbial spoilage. Along PC2, samples 3 and 4 (marked purple in Figure 7) are located in the upper left quadrant and appear to be characterised by positive sensory attributes such as cream flavour and odour combined with a higher pH. This combination indicates lower acidity and preserved freshness, possibly due to an early fermentation stage or minimal microbial metabolism. In contrast, samples 14 and 6 (marked orange in Figure 7), located in the lower right quadrant, are more closely related to fat content, dry matter, and creaminess. These samples likely represent richer, more texturally dense creams, possibly due to higher lipid concentration or longer maturation, which may improve mouthfeel, but may also be associated with more advanced stages of production or slight sensory deterioration, depending on the accompanying microbiological quality. In addition to the previously discussed samples, the remaining cream samples exhibited a number of intermediate characteristics.