## 3 Results and Discussion
### Spirulina Effects on Mozzarella Cheese's Sensory Quality  
As for the QDA, no significant product x replication or product x assessor interactions were observed, suggesting that the training program and the reference frame used in this study were efficacious in ensuring the high reliability of the panel (i.e., products were not evaluated differently in different replications or by different assessors). Table 8 shows a significant diet effect on the sensory profiles of mozzarella cheeses. The samples from the S group were evaluated as being brighter (\(p<0.05\)) with a lower white inner colour (\(p<0.01\)) than the C group. The S mozzarella chees were perceived with a higher butter odour (\(p<0.01\)), a higher whey flavour, and a sweeter and more bitter taste than the samples from the C group (\(p<0.05\)). Furthermore, the panellists perceived higher oiliness (\(p<0.01\)) and moisture (\(p<0.0001\)) intensities in the S samples with a greater milk release when cutting (\(p<0.001\)) and a tendentially higher tenderness (\(p<0.10\)) than in the mozzarella cheeses from the C group, which, on the contrary, were perceived as being more grainy, cohesive, screechy, and having a greater consistency when cutting than the S mozzarella chees (\(p<0.01\)). In a recent study on buffalo mozzarella cheese [11], changes in texture were attributed, at least in part, to the corresponding fatty acid composition, which was lower in saturated fatty acids, such as C14:0, and richer in unsaturated fatty acids, such as C18:1, in products obtained from animals that were fed fresh fodder. The lower melting point of unsaturated fatty acids can produce softer cheeses. Furthermore, some attributes (e.g., bitter taste, flakiness, and grainy texture) may be influenced by more intense proteolysis that occurs in the summer, which, in turn, may contribute to the softening of the mozzarella and may have a direct effect on the flavour through the production of short-chain peptides and amino acids [57]. The greater oiliness could also be due to a different acid composition in the fat. For example, in Friesian cattle, [PERSON] et al. [51], following the administration of 40 g/head/d of Spirulina, observed a reduction in the content of saturated fatty acids in milk, with a consequent increase in MUFA and PUFA compared to the control. The sensory characteristics of fresh mozzarella largely rely on the raw materials and production techniques used. Further investigation is required to evaluate the influence of diverse components, including VOCs, AAs, FAs, and peptides, on each sensory attribute. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & \multicolumn{3}{c}{**External Surface**} & \multicolumn{3}{c}{**Internal Surface**} \\  & \multicolumn{2}{c}{**Group**} & \multicolumn{3}{c}{**Group**} & \multicolumn{1}{c}{**\(p\)**} \\ \cline{2-7}  & **S** & **C** & & **S** & **C** & \\ \hline L* & 93.43 \(\pm\) 0.02 & 92.91 \(\pm\) 0.04 & \textless{}0.0001 & 93.13 \(\pm\) 0.06 & 92.80 \(\pm\) 0.15 & 0.0410 \\ a* & \(-\)2.26 \(\pm\) 0.03 & \(-\)2.13 \(\pm\) 0.03 & \textless{}0.0001 & \(-\)3.42 \(\pm\) 0.03 & \(-\)3.13 \(\pm\) 0.02 & \textless{}0.0001 \\ b* & 0.62 \(\pm\) 0.07 & 0.41 \(\pm\) 0.01 & 0.004 & 4.14 \(\pm\) 0.05 & 3.39 \(\pm\) 0.05 & \textless{}0.0001 \\ \hline \end{tabular}
\end{table} 
Table 7: Values (mean \(\pm\) S.E.) of CIE L*, a*, and b* of the external and internal surfaces of mozzarella cheese from control (C) and Spirulina (S) groups. The data on the distribution of individual preferences (Table 9) show that the information received is able to direct the consumers' judgements. The consumers in blind conditions (P) evaluated both samples from the C and S groups to be greater than the middle value (i.e., 5) (Table 10), meaning there were satisfactory sensory properties in both products. Moreover, the blind evaluation was not influenced by the animals' diet, nor by the ages and sexes of the consumers. No difference was observed between the two groups for expected (E) liking.