CO₂ induced changes in saliva: Effects on biochemical properties, emulsifying and foaming behavior, and dynamic sensory perception during oral processing.

Saliva plays a critical role in oral food processing by influencing taste perception, texture, and retronasal aroma release. While salivary buffering capacity is known to modulate sensory responses, the role of dissolved carbon dioxide in salivary functionality remains poorly understood. We hypothesized that dissolved carbon dioxide altered the biochemical, interfacial, and sensory properties of human saliva. Saliva samples containing or depleted of dissolved carbon dioxide were analyzed for protein composition, enzymatic activity, pH, foaming behavior, and emulsifying capacity under storage times ranging from 0 to 200 min and at calcium concentrations from 0 to 45 mM. Dissolved carbon dioxide significantly altered salivary protein profiles and reduced foam and emulsion stability by enhancing flocculation and creaming behavior. Sensory evaluation demonstrated increased sourness perception during oral processing. These findings highlight dissolved carbon dioxide as an important modulator of salivary functionality and oral sensory perception.