Modelling oral conditions and thickness perception of a starch product

Food components stimulate salivation, and the flow and composition of the saliva also affect the perception of the food product. In starch-containing foods, salivary α-amylase breaks down the starch and this may cause thinning in semi-solid foods. The aims were to determine the importance of salivary composition to perceived thickness. Vanilla custard was assessed for taste intensity, creaminess and thickness. To extend the range of saliva composition and flow, an α-amylase inhibitor was added to the samples at different concentrations and the pH of the samples was lowered by adding citric acid. From each collected spat-out bolus, temperature, pH, dilution factor and α-amylase activity were measured. Addition of amylase inhibitor reduced saliva α-amylase activity and increased perceived thickness and creaminess. Acidification increased mechanical thickness prior to testing and perceived thickness but did not reduce the in situ α-amylase activity because the saliva stimulated by acidified custards was also more concentrated in α-amylase. Alpha-amylase activity varied widely among subjects and so decreasing oral α-amylase activity would not guarantee an increase in perceived thickness and creaminess of starch-based foods.