In addition to the volume of the saliva, the contents of the saliva are also important. Helm et al. "…evaluated the properties of human saliva relevant to its potential contribution to esophageal acid clearance." By measuring the capacity for acid neutralization and plotting titration curves, they identified that saliva and especially its bicarbonate content play an important role in neutralization of esophageal acid in both resting and lozenge-stimulated states.