Assessment of Sialic Acid Content in Dairy Products from Buffalo’s and Goat’s Milk Compared to Cow’s Milk

Sialic acids (SIAs) are bioactive compounds present in glycoproteins and glycolipids, playing key roles in human physiology. N-acetylneuraminic acid (Neu5Ac), the only sialic acid synthesized by humans, contributes to neurodevelopment and immune function, whereas N-glycolylneuraminic acid (Neu5Gc), acquired from animal-derived foods, is potentially harmful, showing pro-inflammatory properties. Accordingly, a high Neu5Ac/Neu5Gc ratio represents an important nutritional indicator. This study quantified the two main forms of SIA in five commercial cheese types (mozzarella, stracchino, caciotta, robiola, ricotta) produced from cow (C), buffalo (B), and goat (G) milk, as well as in laboratory cheesemaking from 1000 g of milk from each species. Neu5Gc concentrations were significantly higher in G cheeses (p < 0.001), while Neu5Ac was more abundant in C cheeses (p < 0.05). Consequently, the Neu5Ac/Neu5Gc ratio was markedly higher in C and B cheeses (24.11 and 21.57, respectively) than in G (1.29), reflecting species-specific glycosylation patterns. Among cheese types, ricotta produced from whey exhibited the highest SIA concentrations among all species, followed by robiola, mozzarella and stracchino. In contrast, caciotta showed the lowest SIA levels. The laboratory cheesemaking trial confirmed that most SIAs remained bound to whey proteins. These findings highlighted the combined effect of milk species and cheesemaking on sialylation, with potential nutritional implications.