The multi-modal sensory effect on sour taste perception during oral processing of starch-thickened fluids

Abstract

Sour taste is one of the fundamental taste attributes and considered as a saliva secretion stimulant facilitating consumers with xerostomia and swallowing difficulties. The dynamic sour taste perception during oral processing of starch-thickened fluid was therefore investigated in this study. Recruited healthy subjects were divided into those with high (H_AMS) and low (L_AMS) salivary α-amylase activity groups and their temporal dominant sensory evaluation were analyzed while oral processing starch-thickened fluid samples with different concentration of citric acid. By simultaneously evaluating the physical and chemical properties of subjects' expectorated fluid/saliva mixtures, the complex and multi-modal interplay between fluid viscosity (tactile perception), citric acid concentration (taste perception), salivary α-amylase activity (binary taste interaction) was successfully demonstrated. The sour taste perception was found to be greatly affected by the continuous starch-thickened fluid hydrolysis by salivary α-amylase, resulting in a gradual production of sweet-tasting oligosaccharides and simultaneous decrease in fluid viscosity, and group variations (H_AMS vs. L_AMS) were pronouncedly observed in the hydrolyzed oligosaccharide concentrations (glucose, maltose, and maltotriose) which suitably corresponded to the selected dominant sensory attributes including perceived taste differences and taste dominant duration. These findings suggest that salivary biochemical properties and the thickened fluid type greatly influence consumers’ sensory perception. This could provide valuable insights for designing and optimizing thickened foods and beverages that are palatable in sensory properties and meet the needs of special consumers.