Salivary flow and turbidity development inconsistently associated with lower taste intensity of vegetables and juices

Abstract

The same phytochemicals that stimulate aversive sensations are often also responsible for purported health benefits in fruits and vegetables. Prior work indicates that some salivary proteins may reduce aversiveness of phytochemicals. In rodents, these salivary binding proteins have been shown to reduce bitter taste of polyphenols and alkaloids, but work in humans has focused primarily on polyphenol astringency (dry, rough, or puckery sensations). In this study, we tested if tastes of vegetable products might correlate to either salivary flow rate or the polyphenol binding capability of saliva, as measured by turbidity development when saliva is mixed with tannic acid. Participants (N = 26) provided chewing-stimulated saliva samples and rated five juices and two chopped vegetables for bitterness, sourness, and sweetness intensity. Saliva was mixed with tannic acid and light absorbance was measured for quantification of haze development. Greater absorbance corresponded to less bitterness for one green vegetable juice blend, less sweetness for two green vegetable juice blends and chopped kale, and less sourness from cranberry juice. Greater salivary flow corresponded to less bitterness from chopped brussels sprouts, and less sweetness from one green vegetable juice blend and chopped kale. These findings indicate that greater salivary flow rate and presence of certain salivary binding proteins is not universally associated with lower aversive tastes from phytochemical-containing foods. Whether associations between these salivary properties are ingredient specific or simply not robustly related to taste in commercial products should be further investigated.