Either with additional amylase or the amylase inhibitor acarbose. Linking oral amylase levels with perceptual sequellae may be complicated by the fact that individuals are accustomed to their own idiosyncratic salivary flow rates and amylase concentrations. Moreover, most studies of oral perception of starch have examined a single time point based on the assumption that amylolytic cleavage of glycosidic bonds occurs at a constant rate; however, in vitro rheological measurements demonstrate this is not the case. Based on these considerations, we chose to examine how perceived viscosity changes in the oral cavity using time-intensity ratings, a method which more closely approximates the real-life perception of food changes over time. The goals of the current study were: 1) to determine how individual differences in salivary amylase levels affect starch viscosity Bortezomib 179324-69-7 breakdown using in vitro rheological measurements and 2) to elucidate how variation in salivary concentrations of the enzyme affects the perception of starch viscosity over time. Finally, despite the numerous environmental sources of variation in salivary amylase, we sought 3) to determine how polymorphisms of AMY1 CNVs relate to salivary amylase concentration and enzymatic activity level, as well as to the perception of starch viscosity. In the present study, we investigated the impact of individual differences in salivary amylase levels on the breakdown of starch viscosity in vitro and as perceived within the oral cavity in vivo. Our findings link variation in the AMY1 gene to salivary amylase levels and activity in vitro, which, in turn, are related to the perceived breakdown of starch viscosity over time in vivo. Specifically, we observed that individuals with high levels of amylase experienced faster and more significant decreases in perceived starch viscosity than did individuals with low levels of amylase. Importantly, this method provides a more realistic assessment of viscosity perception than previous work, since individuals usually manipulate a starchy food in their mouth for several seconds to mix it with saliva before swallowing. Since barely any breakdown occurred in the xanthan gum condition and there was no relationship between XG viscosity change and amylase levels, we conclude that the changes in perceived viscosity of the starch stimulus were due to the action of amylase and not merely to salivary dilution. This is further supported by the relationship between the in vitro viscosity breakdown in the MVAG and the perceived viscosity changes over time in vivo. In this study, individual differences in salivary amylase levels and activity were partially related to AMY1 gene copy number. This finding corroborates the recent study of Perry and colleagues, which found that AMY1 gene copy number is positively correlated with salivary amylase protein concentrations. Interestingly, Perry et al. also found that individuals from populations which historically consumed a high starch diet had significantly more copies of the AMY1 gene than populations who subsisted on a protein-rich diet.